cpython-lru_cache-weakref: Doc/lib/libthreading.tex annotate

annotate Doc/lib/libthreading.tex @ 32527:0da660e05e69 legacy-trunk

"#if WITH_THREAD" is incorrect; must be #ifdef instead; WITH_THREAD isn't always set to an integer value when it's defined.

author	Tim Peters <tim.peters@gmail.com>
date	Wed, 07 Jul 2004 20:42:07 +0000
parents	1536941b547f
children	97768d87394a

rev	line source
8918 acfffe14628e New section header style. Fred Drake <fdrake@acm.org> parents: 8767 diff changeset	1 \section{\module{threading} ---
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	2 Higher-level threading interface}
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	3
8716 760dcf197048 Adjusted to use the new module synopsis support macros. Fred Drake <fdrake@acm.org> parents: 8683 diff changeset	4 \declaremodule{standard}{threading}
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	5 \modulesynopsis{Higher-level threading interface.}
8716 760dcf197048 Adjusted to use the new module synopsis support macros. Fred Drake <fdrake@acm.org> parents: 8683 diff changeset	6
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	7
8767 8434e9d00b5a Fix the synopsis. Fred Drake <fdrake@acm.org> parents: 8716 diff changeset	8 This module constructs higher-level threading interfaces on top of the
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10392 diff changeset	9 lower level \refmodule{thread} module.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	10
26897 3bc2af41c016 - fix use of \refmodule markup Fred Drake <fdrake@acm.org> parents: 26891 diff changeset	11 The \refmodule[dummythreading]{dummy_threading} module is provided for
3bc2af41c016 - fix use of \refmodule markup Fred Drake <fdrake@acm.org> parents: 26891 diff changeset	12 situations where \module{threading} cannot be used because
3bc2af41c016 - fix use of \refmodule markup Fred Drake <fdrake@acm.org> parents: 26891 diff changeset	13 \refmodule{thread} is missing.
26891 bc20e8b46de0 Add dummy_thread[ing] sections and reference these from libthread[ing]. Guido van Rossum <guido@python.org> parents: 22412 diff changeset	14
27114 b2fc494963b2 Strike any hint that from-import-* could ever be reasonable; it's a Fred Drake <fdrake@acm.org> parents: 26897 diff changeset	15 This module defines the following functions and objects:
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	16
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	17 \begin{funcdesc}{activeCount}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	18 Return the number of currently active \class{Thread} objects.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	19 The returned count is equal to the length of the list returned by
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	20 \function{enumerate()}.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	21 A function that returns the number of currently active threads.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	22 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	23
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	24 \begin{funcdesc}{Condition}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	25 A factory function that returns a new condition variable object.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	26 A condition variable allows one or more threads to wait until they
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	27 are notified by another thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	28 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	29
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	30 \begin{funcdesc}{currentThread}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	31 Return the current \class{Thread} object, corresponding to the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	32 caller's thread of control. If the caller's thread of control was not
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	33 created through the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	34 \module{threading} module, a dummy thread object with limited functionality
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	35 is returned.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	36 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	37
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	38 \begin{funcdesc}{enumerate}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	39 Return a list of all currently active \class{Thread} objects.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	40 The list includes daemonic threads, dummy thread objects created
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	41 by \function{currentThread()}, and the main thread. It excludes terminated
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	42 threads and threads that have not yet been started.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	43 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	44
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	45 \begin{funcdesc}{Event}{}
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	46 A factory function that returns a new event object. An event manages
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	47 a flag that can be set to true with the \method{set()} method and
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	48 reset to false with the \method{clear()} method. The \method{wait()}
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	49 method blocks until the flag is true.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	50 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	51
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	52 \begin{funcdesc}{Lock}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	53 A factory function that returns a new primitive lock object. Once
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	54 a thread has acquired it, subsequent attempts to acquire it block,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	55 until it is released; any thread may release it.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	56 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	57
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	58 \begin{funcdesc}{RLock}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	59 A factory function that returns a new reentrant lock object.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	60 A reentrant lock must be released by the thread that acquired it.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	61 Once a thread has acquired a reentrant lock, the same thread may
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	62 acquire it again without blocking; the thread must release it once
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	63 for each time it has acquired it.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	64 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	65
19400 be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	66 \begin{funcdesc}{Semaphore}{\optional{value}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	67 A factory function that returns a new semaphore object. A
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	68 semaphore manages a counter representing the number of \method{release()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	69 calls minus the number of \method{acquire()} calls, plus an initial value.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	70 The \method{acquire()} method blocks if necessary until it can return
19400 be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	71 without making the counter negative. If not given, \var{value} defaults to
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	72 1.
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	73 \end{funcdesc}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	74
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	75 \begin{funcdesc}{BoundedSemaphore}{\optional{value}}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	76 A factory function that returns a new bounded semaphore object. A bounded
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	77 semaphore checks to make sure its current value doesn't exceed its initial
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	78 value. If it does, \exception{ValueError} is raised. In most situations
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	79 semaphores are used to guard resources with limited capacity. If the
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	80 semaphore is released too many times it's a sign of a bug. If not given,
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	81 \var{value} defaults to 1.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	82 \end{funcdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	83
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	84 \begin{classdesc*}{Thread}{}
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	85 A class that represents a thread of control. This class can be safely
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	86 subclassed in a limited fashion.
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	87 \end{classdesc*}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	88
19727 f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	89 \begin{classdesc*}{Timer}{}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	90 A thread that executes a function after a specified interval has passed.
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	91 \end{classdesc*}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	92
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	93 \begin{funcdesc}{settrace}{func}
29689 f4e2e5a5ec62 Fix broken markup, & tweak a couple of things for consistency. Fred Drake <fdrake@acm.org> parents: 29679 diff changeset	94 Set a trace function\index{trace function} for all threads started
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	95 from the \module{threading} module. The \var{func} will be passed to
29689 f4e2e5a5ec62 Fix broken markup, & tweak a couple of things for consistency. Fred Drake <fdrake@acm.org> parents: 29679 diff changeset	96 \function{sys.settrace()} for each thread, before its \method{run()}
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	97 method is called.
29705 1536941b547f Add versionadded info for the 2 new threading module functions Neal Norwitz <nnorwitz@gmail.com> parents: 29689 diff changeset	98 \versionadded{2.3}
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	99 \end{funcdesc}
d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	100
d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	101 \begin{funcdesc}{setprofile}{func}
29689 f4e2e5a5ec62 Fix broken markup, & tweak a couple of things for consistency. Fred Drake <fdrake@acm.org> parents: 29679 diff changeset	102 Set a profile function\index{profile function} for all threads started
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	103 from the \module{threading} module. The \var{func} will be passed to
29689 f4e2e5a5ec62 Fix broken markup, & tweak a couple of things for consistency. Fred Drake <fdrake@acm.org> parents: 29679 diff changeset	104 \function{sys.setprofile()} for each thread, before its \method{run()}
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	105 method is called.
29705 1536941b547f Add versionadded info for the 2 new threading module functions Neal Norwitz <nnorwitz@gmail.com> parents: 29689 diff changeset	106 \versionadded{2.3}
29679 d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	107 \end{funcdesc}
d0f15977f37f Add settrace() and setprofile() functions to the threading library. Jeremy Hylton <jeremy@alum.mit.edu> parents: 27114 diff changeset	108
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	109 Detailed interfaces for the objects are documented below.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	110
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	111 The design of this module is loosely based on Java's threading model.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	112 However, where Java makes locks and condition variables basic behavior
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	113 of every object, they are separate objects in Python. Python's \class{Thread}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	114 class supports a subset of the behavior of Java's Thread class;
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	115 currently, there are no priorities, no thread groups, and threads
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	116 cannot be destroyed, stopped, suspended, resumed, or interrupted. The
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	117 static methods of Java's Thread class, when implemented, are mapped to
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	118 module-level functions.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	119
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	120 All of the methods described below are executed atomically.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	121
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	122
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	123 \subsection{Lock Objects \label{lock-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	124
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	125 A primitive lock is a synchronization primitive that is not owned
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	126 by a particular thread when locked. In Python, it is currently
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	127 the lowest level synchronization primitive available, implemented
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10392 diff changeset	128 directly by the \refmodule{thread} extension module.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	129
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	130 A primitive lock is in one of two states, ``locked'' or ``unlocked''.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	131 It is created in the unlocked state. It has two basic methods,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	132 \method{acquire()} and \method{release()}. When the state is
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	133 unlocked, \method{acquire()} changes the state to locked and returns
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	134 immediately. When the state is locked, \method{acquire()} blocks
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	135 until a call to \method{release()} in another thread changes it to
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	136 unlocked, then the \method{acquire()} call resets it to locked and
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	137 returns. The \method{release()} method should only be called in the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	138 locked state; it changes the state to unlocked and returns
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	139 immediately. When more than one thread is blocked in
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	140 \method{acquire()} waiting for the state to turn to unlocked, only one
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	141 thread proceeds when a \method{release()} call resets the state to
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	142 unlocked; which one of the waiting threads proceeds is not defined,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	143 and may vary across implementations.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	144
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	145 All methods are executed atomically.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	146
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	147 \begin{methoddesc}{acquire}{\optional{blocking\code{ = 1}}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	148 Acquire a lock, blocking or non-blocking.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	149
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	150 When invoked without arguments, block until the lock is
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	151 unlocked, then set it to locked, and return. There is no
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	152 return value in this case.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	153
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	154 When invoked with the \var{blocking} argument set to true, do the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	155 same thing as when called without arguments, and return true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	156
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	157 When invoked with the \var{blocking} argument set to false, do not
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	158 block. If a call without an argument would block, return false
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	159 immediately; otherwise, do the same thing as when called
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	160 without arguments, and return true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	161 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	162
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	163 \begin{methoddesc}{release}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	164 Release a lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	165
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	166 When the lock is locked, reset it to unlocked, and return. If
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	167 any other threads are blocked waiting for the lock to become
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	168 unlocked, allow exactly one of them to proceed.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	169
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	170 Do not call this method when the lock is unlocked.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	171
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	172 There is no return value.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	173 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	174
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	175
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	176 \subsection{RLock Objects \label{rlock-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	177
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	178 A reentrant lock is a synchronization primitive that may be
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	179 acquired multiple times by the same thread. Internally, it uses
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	180 the concepts of ``owning thread'' and ``recursion level'' in
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	181 addition to the locked/unlocked state used by primitive locks. In
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	182 the locked state, some thread owns the lock; in the unlocked
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	183 state, no thread owns it.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	184
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	185 To lock the lock, a thread calls its \method{acquire()} method; this
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	186 returns once the thread owns the lock. To unlock the lock, a
18416 33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	187 thread calls its \method{release()} method.
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	188 \method{acquire()}/\method{release()} call pairs may be nested; only
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	189 the final \method{release()} (the \method{release()} of the outermost
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	190 pair) resets the lock to unlocked and allows another thread blocked in
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	191 \method{acquire()} to proceed.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	192
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	193 \begin{methoddesc}{acquire}{\optional{blocking\code{ = 1}}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	194 Acquire a lock, blocking or non-blocking.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	195
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	196 When invoked without arguments: if this thread already owns
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	197 the lock, increment the recursion level by one, and return
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	198 immediately. Otherwise, if another thread owns the lock,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	199 block until the lock is unlocked. Once the lock is unlocked
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	200 (not owned by any thread), then grab ownership, set the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	201 recursion level to one, and return. If more than one thread
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	202 is blocked waiting until the lock is unlocked, only one at a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	203 time will be able to grab ownership of the lock. There is no
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	204 return value in this case.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	205
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	206 When invoked with the \var{blocking} argument set to true, do the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	207 same thing as when called without arguments, and return true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	208
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	209 When invoked with the \var{blocking} argument set to false, do not
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	210 block. If a call without an argument would block, return false
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	211 immediately; otherwise, do the same thing as when called
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	212 without arguments, and return true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	213 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	214
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	215 \begin{methoddesc}{release}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	216 Release a lock, decrementing the recursion level. If after the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	217 decrement it is zero, reset the lock to unlocked (not owned by any
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	218 thread), and if any other threads are blocked waiting for the lock to
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	219 become unlocked, allow exactly one of them to proceed. If after the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	220 decrement the recursion level is still nonzero, the lock remains
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	221 locked and owned by the calling thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	222
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	223 Only call this method when the calling thread owns the lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	224 Do not call this method when the lock is unlocked.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	225
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	226 There is no return value.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	227 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	228
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	229
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	230 \subsection{Condition Objects \label{condition-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	231
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	232 A condition variable is always associated with some kind of lock;
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	233 this can be passed in or one will be created by default. (Passing
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	234 one in is useful when several condition variables must share the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	235 same lock.)
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	236
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	237 A condition variable has \method{acquire()} and \method{release()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	238 methods that call the corresponding methods of the associated lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	239 It also has a \method{wait()} method, and \method{notify()} and
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	240 \method{notifyAll()} methods. These three must only be called when
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	241 the calling thread has acquired the lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	242
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	243 The \method{wait()} method releases the lock, and then blocks until it
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	244 is awakened by a \method{notify()} or \method{notifyAll()} call for
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	245 the same condition variable in another thread. Once awakened, it
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	246 re-acquires the lock and returns. It is also possible to specify a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	247 timeout.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	248
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	249 The \method{notify()} method wakes up one of the threads waiting for
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	250 the condition variable, if any are waiting. The \method{notifyAll()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	251 method wakes up all threads waiting for the condition variable.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	252
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	253 Note: the \method{notify()} and \method{notifyAll()} methods don't
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	254 release the lock; this means that the thread or threads awakened will
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	255 not return from their \method{wait()} call immediately, but only when
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	256 the thread that called \method{notify()} or \method{notifyAll()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	257 finally relinquishes ownership of the lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	258
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	259 Tip: the typical programming style using condition variables uses the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	260 lock to synchronize access to some shared state; threads that are
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	261 interested in a particular change of state call \method{wait()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	262 repeatedly until they see the desired state, while threads that modify
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	263 the state call \method{notify()} or \method{notifyAll()} when they
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	264 change the state in such a way that it could possibly be a desired
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	265 state for one of the waiters. For example, the following code is a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	266 generic producer-consumer situation with unlimited buffer capacity:
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	267
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	268 \begin{verbatim}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	269 # Consume one item
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	270 cv.acquire()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	271 while not an_item_is_available():
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	272 cv.wait()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	273 get_an_available_item()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	274 cv.release()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	275
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	276 # Produce one item
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	277 cv.acquire()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	278 make_an_item_available()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	279 cv.notify()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	280 cv.release()
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	281 \end{verbatim}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	282
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	283 To choose between \method{notify()} and \method{notifyAll()}, consider
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	284 whether one state change can be interesting for only one or several
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	285 waiting threads. E.g. in a typical producer-consumer situation,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	286 adding one item to the buffer only needs to wake up one consumer
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	287 thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	288
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	289 \begin{classdesc}{Condition}{\optional{lock}}
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	290 If the \var{lock} argument is given and not \code{None}, it must be a
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	291 \class{Lock} or \class{RLock} object, and it is used as the underlying
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	292 lock. Otherwise, a new \class{RLock} object is created and used as
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	293 the underlying lock.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	294 \end{classdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	295
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	296 \begin{methoddesc}{acquire}{*args}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	297 Acquire the underlying lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	298 This method calls the corresponding method on the underlying
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	299 lock; the return value is whatever that method returns.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	300 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	301
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	302 \begin{methoddesc}{release}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	303 Release the underlying lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	304 This method calls the corresponding method on the underlying
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	305 lock; there is no return value.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	306 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	307
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	308 \begin{methoddesc}{wait}{\optional{timeout}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	309 Wait until notified or until a timeout occurs.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	310 This must only be called when the calling thread has acquired the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	311 lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	312
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	313 This method releases the underlying lock, and then blocks until it is
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	314 awakened by a \method{notify()} or \method{notifyAll()} call for the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	315 same condition variable in another thread, or until the optional
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	316 timeout occurs. Once awakened or timed out, it re-acquires the lock
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	317 and returns.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	318
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	319 When the \var{timeout} argument is present and not \code{None}, it
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	320 should be a floating point number specifying a timeout for the
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	321 operation in seconds (or fractions thereof).
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	322
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	323 When the underlying lock is an \class{RLock}, it is not released using
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	324 its \method{release()} method, since this may not actually unlock the
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	325 lock when it was acquired multiple times recursively. Instead, an
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	326 internal interface of the \class{RLock} class is used, which really
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	327 unlocks it even when it has been recursively acquired several times.
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	328 Another internal interface is then used to restore the recursion level
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	329 when the lock is reacquired.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	330 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	331
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	332 \begin{methoddesc}{notify}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	333 Wake up a thread waiting on this condition, if any.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	334 This must only be called when the calling thread has acquired the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	335 lock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	336
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	337 This method wakes up one of the threads waiting for the condition
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	338 variable, if any are waiting; it is a no-op if no threads are waiting.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	339
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	340 The current implementation wakes up exactly one thread, if any are
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	341 waiting. However, it's not safe to rely on this behavior. A future,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	342 optimized implementation may occasionally wake up more than one
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	343 thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	344
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	345 Note: the awakened thread does not actually return from its
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	346 \method{wait()} call until it can reacquire the lock. Since
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	347 \method{notify()} does not release the lock, its caller should.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	348 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	349
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	350 \begin{methoddesc}{notifyAll}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	351 Wake up all threads waiting on this condition. This method acts like
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	352 \method{notify()}, but wakes up all waiting threads instead of one.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	353 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	354
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	355
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	356 \subsection{Semaphore Objects \label{semaphore-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	357
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	358 This is one of the oldest synchronization primitives in the history of
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	359 computer science, invented by the early Dutch computer scientist
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	360 Edsger W. Dijkstra (he used \method{P()} and \method{V()} instead of
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	361 \method{acquire()} and \method{release()}).
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	362
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	363 A semaphore manages an internal counter which is decremented by each
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	364 \method{acquire()} call and incremented by each \method{release()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	365 call. The counter can never go below zero; when \method{acquire()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	366 finds that it is zero, it blocks, waiting until some other thread
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	367 calls \method{release()}.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	368
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	369 \begin{classdesc}{Semaphore}{\optional{value}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	370 The optional argument gives the initial value for the internal
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	371 counter; it defaults to \code{1}.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	372 \end{classdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	373
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	374 \begin{methoddesc}{acquire}{\optional{blocking}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	375 Acquire a semaphore.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	376
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	377 When invoked without arguments: if the internal counter is larger than
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	378 zero on entry, decrement it by one and return immediately. If it is
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	379 zero on entry, block, waiting until some other thread has called
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	380 \method{release()} to make it larger than zero. This is done with
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	381 proper interlocking so that if multiple \method{acquire()} calls are
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	382 blocked, \method{release()} will wake exactly one of them up. The
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	383 implementation may pick one at random, so the order in which blocked
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	384 threads are awakened should not be relied on. There is no return
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	385 value in this case.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	386
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	387 When invoked with \var{blocking} set to true, do the same thing as
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	388 when called without arguments, and return true.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	389
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	390 When invoked with \var{blocking} set to false, do not block. If a
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	391 call without an argument would block, return false immediately;
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	392 otherwise, do the same thing as when called without arguments, and
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	393 return true.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	394 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	395
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	396 \begin{methoddesc}{release}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	397 Release a semaphore,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	398 incrementing the internal counter by one. When it was zero on
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	399 entry and another thread is waiting for it to become larger
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	400 than zero again, wake up that thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	401 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	402
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	403
19400 be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	404 \subsubsection{\class{Semaphore} Example \label{semaphore-examples}}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	405
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	406 Semaphores are often used to guard resources with limited capacity, for
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	407 example, a database server. In any situation where the size of the resource
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	408 size is fixed, you should use a bounded semaphore. Before spawning any
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	409 worker threads, your main thread would initialize the semaphore:
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	410
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	411 \begin{verbatim}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	412 maxconnections = 5
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	413 ...
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	414 pool_sema = BoundedSemaphore(value=maxconnections)
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	415 \end{verbatim}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	416
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	417 Once spawned, worker threads call the semaphore's acquire and release
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	418 methods when they need to connect to the server:
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	419
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	420 \begin{verbatim}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	421 pool_sema.acquire()
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	422 conn = connectdb()
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	423 ... use connection ...
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	424 conn.close()
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	425 pool_sema.release()
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	426 \end{verbatim}
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	427
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	428 The use of a bounded semaphore reduces the chance that a programming error
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	429 which causes the semaphore to be released more than it's acquired will go
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	430 undetected.
be5be989caff Added documentation for BoundedSemaphore(), contributed by Skip Montanaro. Fred Drake <fdrake@acm.org> parents: 18416 diff changeset	431
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	432
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	433 \subsection{Event Objects \label{event-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	434
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	435 This is one of the simplest mechanisms for communication between
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	436 threads: one thread signals an event and other threads wait for it.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	437
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	438 An event object manages an internal flag that can be set to true with
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	439 the \method{set()} method and reset to false with the \method{clear()}
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	440 method. The \method{wait()} method blocks until the flag is true.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	441
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	442
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	443 \begin{classdesc}{Event}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	444 The internal flag is initially false.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	445 \end{classdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	446
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	447 \begin{methoddesc}{isSet}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	448 Return true if and only if the internal flag is true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	449 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	450
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	451 \begin{methoddesc}{set}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	452 Set the internal flag to true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	453 All threads waiting for it to become true are awakened.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	454 Threads that call \method{wait()} once the flag is true will not block
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	455 at all.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	456 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	457
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	458 \begin{methoddesc}{clear}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	459 Reset the internal flag to false.
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	460 Subsequently, threads calling \method{wait()} will block until
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	461 \method{set()} is called to set the internal flag to true again.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	462 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	463
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	464 \begin{methoddesc}{wait}{\optional{timeout}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	465 Block until the internal flag is true.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	466 If the internal flag is true on entry, return immediately. Otherwise,
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	467 block until another thread calls \method{set()} to set the flag to
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	468 true, or until the optional timeout occurs.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	469
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	470 When the timeout argument is present and not \code{None}, it should be a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	471 floating point number specifying a timeout for the operation in
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	472 seconds (or fractions thereof).
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	473 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	474
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	475
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	476 \subsection{Thread Objects \label{thread-objects}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	477
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	478 This class represents an activity that is run in a separate thread
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	479 of control. There are two ways to specify the activity: by
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	480 passing a callable object to the constructor, or by overriding the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	481 \method{run()} method in a subclass. No other methods (except for the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	482 constructor) should be overridden in a subclass. In other words,
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	483 \emph{only} override the \method{__init__()} and \method{run()}
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	484 methods of this class.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	485
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	486 Once a thread object is created, its activity must be started by
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	487 calling the thread's \method{start()} method. This invokes the
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	488 \method{run()} method in a separate thread of control.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	489
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	490 Once the thread's activity is started, the thread is considered
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	491 'alive' and 'active' (these concepts are almost, but not quite
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	492 exactly, the same; their definition is intentionally somewhat
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	493 vague). It stops being alive and active when its \method{run()}
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	494 method terminates -- either normally, or by raising an unhandled
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	495 exception. The \method{isAlive()} method tests whether the thread is
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	496 alive.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	497
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	498 Other threads can call a thread's \method{join()} method. This blocks
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	499 the calling thread until the thread whose \method{join()} method is
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	500 called is terminated.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	501
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	502 A thread has a name. The name can be passed to the constructor,
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	503 set with the \method{setName()} method, and retrieved with the
f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	504 \method{getName()} method.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	505
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	506 A thread can be flagged as a ``daemon thread''. The significance
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	507 of this flag is that the entire Python program exits when only
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	508 daemon threads are left. The initial value is inherited from the
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	509 creating thread. The flag can be set with the \method{setDaemon()}
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	510 method and retrieved with the \method{isDaemon()} method.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	511
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	512 There is a ``main thread'' object; this corresponds to the
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	513 initial thread of control in the Python program. It is not a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	514 daemon thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	515
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	516 There is the possibility that ``dummy thread objects'' are
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	517 created. These are thread objects corresponding to ``alien
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	518 threads''. These are threads of control started outside the
18416 33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make Fred Drake <fdrake@acm.org> parents: 18009 diff changeset	519 threading module, such as directly from C code. Dummy thread objects
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	520 have limited functionality; they are always considered alive,
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	521 active, and daemonic, and cannot be \method{join()}ed. They are never
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	522 deleted, since it is impossible to detect the termination of alien
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	523 threads.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	524
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	525
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	526 \begin{classdesc}{Thread}{group=None, target=None, name=None,
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	527 args=(), kwargs=\{\}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	528 This constructor should always be called with keyword
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	529 arguments. Arguments are:
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	530
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	531 \var{group} should be \code{None}; reserved for future extension when
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	532 a \class{ThreadGroup} class is implemented.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	533
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	534 \var{target} is the callable object to be invoked by the
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	535 \method{run()} method. Defaults to \code{None}, meaning nothing is
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	536 called.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	537
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	538 \var{name} is the thread name. By default, a unique name is
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	539 constructed of the form ``Thread-\var{N}'' where \var{N} is a small
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	540 decimal number.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	541
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	542 \var{args} is the argument tuple for the target invocation. Defaults
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	543 to \code{()}.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	544
18009 50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	545 \var{kwargs} is a dictionary of keyword arguments for the target
50e3380b086a Some general cleanup of the threading module documentation, including Fred Drake <fdrake@acm.org> parents: 10730 diff changeset	546 invocation. Defaults to \code{\{\}}.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	547
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	548 If the subclass overrides the constructor, it must make sure
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	549 to invoke the base class constructor (\code{Thread.__init__()})
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	550 before doing anything else to the thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	551 \end{classdesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	552
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	553 \begin{methoddesc}{start}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	554 Start the thread's activity.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	555
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	556 This must be called at most once per thread object. It
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	557 arranges for the object's \method{run()} method to be invoked in a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	558 separate thread of control.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	559 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	560
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	561 \begin{methoddesc}{run}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	562 Method representing the thread's activity.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	563
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	564 You may override this method in a subclass. The standard
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	565 \method{run()} method invokes the callable object passed to the
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	566 object's constructor as the \var{target} argument, if any, with
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	567 sequential and keyword arguments taken from the \var{args} and
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	568 \var{kwargs} arguments, respectively.
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	569 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	570
10392 f54bac5af98c Fixed tons of small markup problems. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	571 \begin{methoddesc}{join}{\optional{timeout}}
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	572 Wait until the thread terminates.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	573 This blocks the calling thread until the thread whose \method{join()}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	574 method is called terminates -- either normally or through an
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	575 unhandled exception -- or until the optional timeout occurs.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	576
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	577 When the \var{timeout} argument is present and not \code{None}, it
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	578 should be a floating point number specifying a timeout for the
8683 a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	579 operation in seconds (or fractions thereof).
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	580
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	581 A thread can be \method{join()}ed many times.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	582
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	583 A thread cannot join itself because this would cause a
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	584 deadlock.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	585
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	586 It is an error to attempt to \method{join()} a thread before it has
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	587 been started.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	588 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	589
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	590 \begin{methoddesc}{getName}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	591 Return the thread's name.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	592 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	593
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	594 \begin{methoddesc}{setName}{name}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	595 Set the thread's name.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	596
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	597 The name is a string used for identification purposes only.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	598 It has no semantics. Multiple threads may be given the same
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	599 name. The initial name is set by the constructor.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	600 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	601
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	602 \begin{methoddesc}{isAlive}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	603 Return whether the thread is alive.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	604
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	605 Roughly, a thread is alive from the moment the \method{start()} method
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	606 returns until its \method{run()} method terminates.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	607 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	608
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	609 \begin{methoddesc}{isDaemon}{}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	610 Return the thread's daemon flag.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	611 \end{methoddesc}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	612
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	613 \begin{methoddesc}{setDaemon}{daemonic}
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	614 Set the thread's daemon flag to the Boolean value \var{daemonic}.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	615 This must be called before \method{start()} is called.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	616
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	617 The initial value is inherited from the creating thread.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	618
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	619 The entire Python program exits when no active non-daemon
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	620 threads are left.
a0324a3068e9 Added libthreading.tex ; this is mostly the contents of threading_api.py, Andrew M. Kuchling <amk@amk.ca> parents: diff changeset	621 \end{methoddesc}
19727 f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	622
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	623
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	624 \subsection{Timer Objects \label{timer-objects}}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	625
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	626 This class represents an action that should be run only after a
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	627 certain amount of time has passed --- a timer. \class{Timer} is a
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	628 subclass of \class{Thread} and as such also functions as an example of
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	629 creating custom threads.
19727 f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	630
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	631 Timers are started, as with threads, by calling their \method{start()}
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	632 method. The timer can be stopped (before its action has begun) by
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	633 calling the \method{cancel()} method. The interval the timer will
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	634 wait before executing its action may not be exactly the same as the
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	635 interval specified by the user.
19727 f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	636
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	637 For example:
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	638 \begin{verbatim}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	639 def hello():
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	640 print "hello, world"
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	641
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	642 t = Timer(30.0, hello)
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	643 t.start() # after 30 seconds, "hello, world" will be printed
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	644 \end{verbatim}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	645
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	646 \begin{classdesc}{Timer}{interval, function, args=[], kwargs=\{\}}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	647 Create a timer that will run \var{function} with arguments \var{args} and
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	648 keyword arguments \var{kwargs}, after \var{interval} seconds have passed.
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	649 \end{classdesc}
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	650
f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	651 \begin{methoddesc}{cancel}{}
22412 36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	652 Stop the timer, and cancel the execution of the timer's action. This
36c52cfbd0b7 Adjust some poor wording in the text that explains what events are used Fred Drake <fdrake@acm.org> parents: 19727 diff changeset	653 will only work if the timer is still in its waiting stage.
19727 f3036d4e3c22 Patch #428326: New class threading.Timer. Martin v. Löwis <martin@v.loewis.de> parents: 19400 diff changeset	654 \end{methoddesc}

Mercurial > cpython-lru_cache-weakref

annotate Doc/lib/libthreading.tex @ 32527:0da660e05e69 legacy-trunk