Mercurial > cpython-lru_cache-weakref
diff Python/random.c @ 85468:acc7439b1406
Issue #18756: os.urandom() now uses a lazily-opened persistent file descriptor, so as to avoid using many file descriptors when run in parallel from multiple threads.
| author | Antoine Pitrou <solipsis@pitrou.net> |
|---|---|
| date | Sat, 31 Aug 2013 00:26:02 +0200 |
| parents | ef889c3d5dc6 |
| children | b0295cc736d8 |
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--- a/Python/random.c Sat Aug 31 00:12:37 2013 +0200 +++ b/Python/random.c Sat Aug 31 00:26:02 2013 +0200 @@ -90,6 +90,7 @@ #if !defined(MS_WINDOWS) && !defined(__VMS) +static int urandom_fd = -1; /* Read size bytes from /dev/urandom into buffer. Call Py_FatalError() on error. */ @@ -133,18 +134,30 @@ if (size <= 0) return 0; - Py_BEGIN_ALLOW_THREADS - fd = _Py_open("/dev/urandom", O_RDONLY); - Py_END_ALLOW_THREADS - if (fd < 0) - { - if (errno == ENOENT || errno == ENXIO || - errno == ENODEV || errno == EACCES) - PyErr_SetString(PyExc_NotImplementedError, - "/dev/urandom (or equivalent) not found"); + if (urandom_fd >= 0) + fd = urandom_fd; + else { + Py_BEGIN_ALLOW_THREADS + fd = _Py_open("/dev/urandom", O_RDONLY); + Py_END_ALLOW_THREADS + if (fd < 0) + { + if (errno == ENOENT || errno == ENXIO || + errno == ENODEV || errno == EACCES) + PyErr_SetString(PyExc_NotImplementedError, + "/dev/urandom (or equivalent) not found"); + else + PyErr_SetFromErrno(PyExc_OSError); + return -1; + } + if (urandom_fd >= 0) { + /* urandom_fd was initialized by another thread while we were + not holding the GIL, keep it. */ + close(fd); + fd = urandom_fd; + } else - PyErr_SetFromErrno(PyExc_OSError); - return -1; + urandom_fd = fd; } Py_BEGIN_ALLOW_THREADS @@ -168,12 +181,20 @@ PyErr_Format(PyExc_RuntimeError, "Failed to read %zi bytes from /dev/urandom", size); - close(fd); return -1; } - close(fd); return 0; } + +static void +dev_urandom_close(void) +{ + if (urandom_fd >= 0) { + close(urandom_fd); + urandom_fd = -1; + } +} + #endif /* !defined(MS_WINDOWS) && !defined(__VMS) */ /* Fill buffer with pseudo-random bytes generated by a linear congruent @@ -271,3 +292,11 @@ #endif } } + +void +_PyRandom_Fini(void) +{ +#if !defined(MS_WINDOWS) && !defined(__VMS) + dev_urandom_close(); +#endif +}