Mercurial > cpython-lru_cache-weakref

annotate Doc/lib/libthread.tex @ 27998:e27f58a50737 legacy-trunk

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
SF bug #690377: Dud footnote reference in distutils docs
author Raymond Hettinger <python@rcn.com>
date Fri, 21 Feb 2003 02:47:09 +0000
parents 3bc2af41c016
children 4fc56cae4eb8
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
8918
acfffe14628e New section header style.
Fred Drake <fdrake@acm.org>
parents: 8716
diff changeset
1 \section{\module{thread} ---
10657
d203cb9ece37 Nits. Reference to signal module becomes a hyperlink.
Fred Drake <fdrake@acm.org>
parents: 9546
diff changeset
2 Multiple threads of control}
d203cb9ece37 Nits. Reference to signal module becomes a hyperlink.
Fred Drake <fdrake@acm.org>
parents: 9546
diff changeset
3
8716
760dcf197048 Adjusted to use the new module synopsis support macros.
Fred Drake <fdrake@acm.org>
parents: 8617
diff changeset
4 \declaremodule{builtin}{thread}
8918
acfffe14628e New section header style.
Fred Drake <fdrake@acm.org>
parents: 8716
diff changeset
5 \modulesynopsis{Create multiple threads of control within one interpreter.}
8716
760dcf197048 Adjusted to use the new module synopsis support macros.
Fred Drake <fdrake@acm.org>
parents: 8617
diff changeset
6
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
7
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
8 This module provides low-level primitives for working with multiple
2527
815dfaa6a778 small changes by Soren Larsen
Guido van Rossum <guido@python.org>
parents: 1776
diff changeset
9 threads (a.k.a.\ \dfn{light-weight processes} or \dfn{tasks}) --- multiple
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
10 threads of control sharing their global data space. For
2527
815dfaa6a778 small changes by Soren Larsen
Guido van Rossum <guido@python.org>
parents: 1776
diff changeset
11 synchronization, simple locks (a.k.a.\ \dfn{mutexes} or \dfn{binary
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
12 semaphores}) are provided.
7141
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
13 \index{light-weight processes}
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
14 \index{processes, light-weight}
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
15 \index{binary semaphores}
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
16 \index{semaphores, binary}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
17
25881
8d44d614941d Clarify what versions of Windows are supported, and add Linux
Fred Drake <fdrake@acm.org>
parents: 22920
diff changeset
18 The module is optional. It is supported on Windows, Linux, SGI
7222
10fdf16f4de9 Consistently use \POSIX{} to denote POSIX. There were at least two different
Fred Drake <fdrake@acm.org>
parents: 7141
diff changeset
19 IRIX, Solaris 2.x, as well as on systems that have a \POSIX{} thread
26891
bc20e8b46de0 Add dummy_thread[ing] sections and reference these from libthread[ing].
Guido van Rossum <guido@python.org>
parents: 25881
diff changeset
20 (a.k.a. ``pthread'') implementation. For systems lacking the \module{thread}
26897
3bc2af41c016 - fix use of \refmodule markup
Fred Drake <fdrake@acm.org>
parents: 26891
diff changeset
21 module, the \refmodule[dummythread]{dummy_thread} module is available.
3bc2af41c016 - fix use of \refmodule markup
Fred Drake <fdrake@acm.org>
parents: 26891
diff changeset
22 It duplicates this module's interface and can be
3bc2af41c016 - fix use of \refmodule markup
Fred Drake <fdrake@acm.org>
parents: 26891
diff changeset
23 used as a drop-in replacement.
7141
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
24 \index{pthreads}
21062
bc02c3b09626 Clean up some markup cruft. A number of the macros that take no
Fred Drake <fdrake@acm.org>
parents: 20468
diff changeset
25 \indexii{threads}{\POSIX}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
26
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
27 It defines the following constant and functions:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
28
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
29 \begin{excdesc}{error}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
30 Raised on thread-specific errors.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
31 \end{excdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
32
8564
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
33 \begin{datadesc}{LockType}
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
34 This is the type of lock objects.
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
35 \end{datadesc}
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
36
10657
d203cb9ece37 Nits. Reference to signal module becomes a hyperlink.
Fred Drake <fdrake@acm.org>
parents: 9546
diff changeset
37 \begin{funcdesc}{start_new_thread}{function, args\optional{, kwargs}}
20468
ebfd87e87884 Partial patch from SF #452266, by Jason Petrone.
Guido van Rossum <guido@python.org>
parents: 12243
diff changeset
38 Start a new thread and return its identifier. The thread executes the function
ebfd87e87884 Partial patch from SF #452266, by Jason Petrone.
Guido van Rossum <guido@python.org>
parents: 12243
diff changeset
39 \var{function} with the argument list \var{args} (which must be a tuple). The
ebfd87e87884 Partial patch from SF #452266, by Jason Petrone.
Guido van Rossum <guido@python.org>
parents: 12243
diff changeset
40 optional \var{kwargs} argument specifies a dictionary of keyword arguments.
ebfd87e87884 Partial patch from SF #452266, by Jason Petrone.
Guido van Rossum <guido@python.org>
parents: 12243
diff changeset
41 When the function returns, the thread silently exits. When the function
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
42 terminates with an unhandled exception, a stack trace is printed and
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
43 then the thread exits (but other threads continue to run).
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
44 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
45
2576
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
46 \begin{funcdesc}{exit}{}
8564
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
47 Raise the \exception{SystemExit} exception. When not caught, this
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
48 will cause the thread to exit silently.
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
49 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
50
2576
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
51 \begin{funcdesc}{exit_thread}{}
8617
46b472ecb0f9 Added \deprecated to exit_thread() function.
Fred Drake <fdrake@acm.org>
parents: 8564
diff changeset
52 \deprecated{1.5.2}{Use \function{exit()}.}
8564
e87d22c7de3c Document optional kwargs argument to start_new_thread(). Also
Guido van Rossum <guido@python.org>
parents: 7877
diff changeset
53 This is an obsolete synonym for \function{exit()}.
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
54 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
55
2576
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
56 %\begin{funcdesc}{exit_prog}{status}
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
57 %Exit all threads and report the value of the integer argument
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
58 %\var{status} as the exit status of the entire program.
10657
d203cb9ece37 Nits. Reference to signal module becomes a hyperlink.
Fred Drake <fdrake@acm.org>
parents: 9546
diff changeset
59 %\strong{Caveat:} code in pending \keyword{finally} clauses, in this thread
2576
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
60 %or in other threads, is not executed.
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
61 %\end{funcdesc}
f47bc5554418 mass changes; fix titles; add examples; correct typos; clarifications;
Guido van Rossum <guido@python.org>
parents: 2527
diff changeset
62
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
63 \begin{funcdesc}{allocate_lock}{}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
64 Return a new lock object. Methods of locks are described below. The
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
65 lock is initially unlocked.
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
66 \end{funcdesc}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
67
1776
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
68 \begin{funcdesc}{get_ident}{}
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
69 Return the `thread identifier' of the current thread. This is a
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
70 nonzero integer. Its value has no direct meaning; it is intended as a
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
71 magic cookie to be used e.g. to index a dictionary of thread-specific
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
72 data. Thread identifiers may be recycled when a thread exits and
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
73 another thread is created.
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
74 \end{funcdesc}
5257af80e161 * Doc/libfuncs.tex: don't use $math$ in description of pow(x,y,z);
Guido van Rossum <guido@python.org>
parents: 1471
diff changeset
75
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
76
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
77 Lock objects have the following methods:
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
78
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
79 \begin{methoddesc}[lock]{acquire}{\optional{waitflag}}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
80 Without the optional argument, this method acquires the lock
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
81 unconditionally, if necessary waiting until it is released by another
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
82 thread (only one thread at a time can acquire a lock --- that's their
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
83 reason for existence), and returns \code{None}. If the integer
9546
aa961a46ae9e Minor markup nit to ease conversion processing.
Fred Drake <fdrake@acm.org>
parents: 8918
diff changeset
84 \var{waitflag} argument is present, the action depends on its
aa961a46ae9e Minor markup nit to ease conversion processing.
Fred Drake <fdrake@acm.org>
parents: 8918
diff changeset
85 value: if it is zero, the lock is only acquired if it can be acquired
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
86 immediately without waiting, while if it is nonzero, the lock is
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
87 acquired unconditionally as before. If an argument is present, the
22920
2392af05f052 Update docs for bool changes by Guido around April 6
Neal Norwitz <nnorwitz@gmail.com>
parents: 21062
diff changeset
88 return value is \code{True} if the lock is acquired successfully,
2392af05f052 Update docs for bool changes by Guido around April 6
Neal Norwitz <nnorwitz@gmail.com>
parents: 21062
diff changeset
89 \code{False} if not.
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
90 \end{methoddesc}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
91
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
92 \begin{methoddesc}[lock]{release}{}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
93 Releases the lock. The lock must have been acquired earlier, but not
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
94 necessarily by the same thread.
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
95 \end{methoddesc}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
96
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
97 \begin{methoddesc}[lock]{locked}{}
22920
2392af05f052 Update docs for bool changes by Guido around April 6
Neal Norwitz <nnorwitz@gmail.com>
parents: 21062
diff changeset
98 Return the status of the lock:\ \code{True} if it has been acquired by
2392af05f052 Update docs for bool changes by Guido around April 6
Neal Norwitz <nnorwitz@gmail.com>
parents: 21062
diff changeset
99 some thread, \code{False} if not.
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
100 \end{methoddesc}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
101
7096
5bb884527446 Consistency: "{\bf ...}" ==> "\strong{...}"
Fred Drake <fdrake@acm.org>
parents: 6023
diff changeset
102 \strong{Caveats:}
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
103
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
104 \begin{itemize}
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
105 \item
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
106 Threads interact strangely with interrupts: the
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
107 \exception{KeyboardInterrupt} exception will be received by an
10657
d203cb9ece37 Nits. Reference to signal module becomes a hyperlink.
Fred Drake <fdrake@acm.org>
parents: 9546
diff changeset
108 arbitrary thread. (When the \refmodule{signal}\refbimodindex{signal}
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
109 module is available, interrupts always go to the main thread.)
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
110
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
111 \item
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
112 Calling \function{sys.exit()} or raising the \exception{SystemExit}
12243
be3e0d197522 Noted by Guido:
Fred Drake <fdrake@acm.org>
parents: 10657
diff changeset
113 exception is equivalent to calling \function{exit()}.
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
114
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
115 \item
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
116 Not all built-in functions that may block waiting for I/O allow other
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
117 threads to run. (The most popular ones (\function{time.sleep()},
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
118 \method{\var{file}.read()}, \function{select.select()}) work as
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
119 expected.)
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
120
6023
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
121 \item
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
122 It is not possible to interrupt the \method{acquire()} method on a lock
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
123 --- the \exception{KeyboardInterrupt} exception will happen after the
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
124 lock has been acquired.
6023
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
125
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
126 \item
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
127 When the main thread exits, it is system defined whether the other
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
128 threads survive. On SGI IRIX using the native thread implementation,
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
129 they survive. On most other systems, they are killed without
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
130 executing \keyword{try} ... \keyword{finally} clauses or executing
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
131 object destructors.
7141
b81fb67d908d Added a bunch of "concept" index entries.
Fred Drake <fdrake@acm.org>
parents: 7096
diff changeset
132 \indexii{threads}{IRIX}
6023
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
133
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
134 \item
7817
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
135 When the main thread exits, it does not do any of its usual cleanup
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
136 (except that \keyword{try} ... \keyword{finally} clauses are honored),
461738aaa533 Logical markup.
Fred Drake <fdrake@acm.org>
parents: 7712
diff changeset
137 and the standard I/O files are not flushed.
6023
6a25d8110b00 Updated platform specific notes (it is now more common to have this)
Guido van Rossum <guido@python.org>
parents: 5818
diff changeset
138
1471
2ec96140a36b Restructured library documentation
Guido van Rossum <guido@python.org>
parents:
diff changeset
139 \end{itemize}