New submission from Charles-François Natali:
As discussed in
http://mail.python.org/pipermail/python-dev/2013-August/128204.html, I think
that we shouldn't let EINTR leak to Python code: it should be handled properly
by the C code, so that users (and the Python part of the stdlib) don't have to
worry about this low-level historical nuisance.
For code that doesn't release the GIL, we could simply use this glibc macro:
# define TEMP_FAILURE_RETRY(expression) \
(__extension__ \
({ long int __result; \
do __result = (long int) (expression); \
while (__result == -1L && errno == EINTR); \
__result; }))
#endif
Now, I'm not sure about how to best handle this for code that releases the GIL.
Basically:
Py_BEGIN_ALLOW_THREADS
pid = waitpid(pid, &status, options);
Py_END_ALLOW_THREADS
should become
begin_handle_eintr:
Py_BEGIN_ALLOW_THREADS
pid = waitpid(pid, &status, options);
Py_END_ALLOW_THREADS
if (pid < 0 && errno == EINTR) {
if (PyErr_CheckSignals())
return NULL;
goto begin_handle_eintr;
}
Should we do this with a macro?
If yes, should it be a new one that should be placed around
Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS (like BEGIN_SELECT_LOOP in
selectmodule.c) or could we have a single macro that would do both (i.e.
release the GIL / reacquire the GIL, and try again in case of EINTR, unless a
signal handler raised an exception)?
>From a cursory look, the main files affected would be:
Modules/fcntlmodule.c
Modules/ossaudiodev.c
Modules/posixmodule.c
Modules/selectmodule.c
Modules/selectmodule.c
Modules/signalmodule.c
Modules/socketmodule.c
Modules/syslogmodule.c
----------
messages: 196555
nosy: neologix
priority: normal
severity: normal
stage: needs patch
status: open
title: handle EINTR in the stdlib
type: enhancement
versions: Python 3.4
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue18885>
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