Issue31171
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Created on 2017-08-10 07:21 by hongxu, last changed 2022-04-11 14:58 by admin.
Pull Requests | |||
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URL | Status | Linked | Edit |
PR 10563 | closed | hongxu, 2018-11-16 07:31 | |
PR 3054 | closed | hongxu, 2018-11-16 07:39 | |
PR 13353 | open | hongxu, 2019-05-16 03:15 |
Messages (5) | |||
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msg300052 - (view) | Author: Hongxu Jia (hongxu) * | Date: 2017-08-10 07:21 | |
To build python for embedded Linux systems, (http://www.yoctoproject.org/docs/2.3.1/yocto-project-qs/yocto-project-qs.html) The 32-bit python's multiprocessing.BoundedSemaphore could not work. 1. Prerequisite - Build 32bit python on 64bit host, add '-m32' to gcc - Cross compling on linux platform, not have `-pthread' In configure.ac, ac_cv_pthread=no while cross compiling ... 2001 AC_MSG_CHECKING(whether $CC accepts -pthread) 2002 AC_CACHE_VAL(ac_cv_pthread, 2003 [ac_save_cc="$CC" 2004 CC="$CC -pthread" 2005 AC_RUN_IFELSE([AC_LANG_SOURCE([[ [snip] 2018 ]])],[ac_cv_pthread=yes],[ac_cv_pthread=no],[ac_cv_pthread=no]) ... — Macro: AC_RUN_IFELSE (input, [action-if-true], [action-if-false], [action-if-cross-compiling]) 2. Reproduce with simplifying the prerequisite $ git clone https://github.com/python/cpython.git; cd ./cpython $ ac_cv_pthread=no CC="gcc -m32" ./configure $ make -j 10 $ ./python -c "import multiprocessing; pool_sema = multiprocessing.BoundedSemaphore(value=1); pool_sema.acquire(); pool_sema.release()" Traceback (most recent call last): File "<string>", line 1, in <module> ValueError: semaphore or lock released too many times And the issue also caused invoking put of 'multiprocessing.Queue' hung. $ ./python -c "import multiprocessing; queue_instance = multiprocessing.Queue(); queue_instance.put(('install'))" |
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msg300053 - (view) | Author: Hongxu Jia (hongxu) * | Date: 2017-08-10 07:22 | |
3. Analysis 1) The multiprocessing invokes named semaphore in C library (sem_open/sem_post/sem_getvalue/sem_unlink in ./Modules/_multiprocessing/semaphore.c) 2) The glibc defines two different sem_getvalue since the following commit. https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/sem_getvalue.c;h=1432cc795ece84d5bf31c7e5cafe01cc1a09d98d;hb=042e1521c794a945edc43b5bfa7e69ad70420524 The `__new_sem_getvalue' is the sem_getvalue@@GLIBC_2.1 which work with named semaphore `sem_open' The `__old_sem_getvalue' is the old version sem_getvalue@GLIBC_2.0 which work with unamed semaphore `sem_init' In 32-bit C library, it provides both of them. $ nm -g /lib/i386-linux-gnu/libpthread-2.23.so 0000df30 T sem_getvalue@GLIBC_2.0 0000df10 T sem_getvalue@@GLIBC_2.1 3) In multiprocessing, it invokes sem_open, so sem_getvalue@@GLIBC_2.1 is supposed. If `-pthread' or `-lpthread' not passed to gcc, the compiled _multiprocessing dynamic library could not explicitly linked to sem_getvalue@@GLIBC_2.1 $ nm -g ./build/lib.linux-x86_64-3.7/_multiprocessing.cpython-37m-i386-linux-gnu.so U sem_getvalue U sem_open If `-pthread' or `-lpthread' passed to gcc: $ nm -g ./build/lib.linux-x86_64-3.7/_multiprocessing.cpython-37m-i386-linux-gnu.so U sem_getvalue@@GLIBC_2.1 U sem_open@@GLIBC_2.1.1 4) On 32-bit OS, the multiprocessing was incorrectly linked to sem_getvalue@GLIBC_2.0 which caused the issue. |
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msg300054 - (view) | Author: Hongxu Jia (hongxu) * | Date: 2017-08-10 07:23 | |
4. Solution For cross compiling, there is no `-pthread', so we should explicitly add `-lpthread' to build multiprocessing. Peterson tried to do it in the following commit: ... commit e711cafab13efc9c1fe6c5cd75826401445eb585 Author: Benjamin Peterson <benjamin@python.org> Date: Wed Jun 11 16:44:04 2008 +0000 Merged revisions 64104,64117 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ... git show e711cafab13efc9c1fe6c5cd75826401445eb585 -- setup.py --- a/setup.py +++ b/setup.py @@ -1110,6 +1110,56 @@ class PyBuildExt(build_ext): # _fileio -- supposedly cross platform exts.append(Extension('_fileio', ['_fileio.c'])) + # Richard Oudkerk's multiprocessing module + if platform == 'win32': # Windows + macros = dict() + libraries = ['ws2_32'] + + elif platform == 'darwin': # Mac OSX + macros = dict( + HAVE_SEM_OPEN=1, + HAVE_SEM_TIMEDWAIT=0, + HAVE_FD_TRANSFER=1, + HAVE_BROKEN_SEM_GETVALUE=1 + ) + libraries = [] + + elif platform == 'cygwin': # Cygwin + macros = dict( + HAVE_SEM_OPEN=1, + HAVE_SEM_TIMEDWAIT=1, + HAVE_FD_TRANSFER=0, + HAVE_BROKEN_SEM_UNLINK=1 + ) + libraries = [] + else: # Linux and other unices + macros = dict( + HAVE_SEM_OPEN=1, + HAVE_SEM_TIMEDWAIT=1, + HAVE_FD_TRANSFER=1 + ) + libraries = ['rt'] + + if platform == 'win32': + multiprocessing_srcs = [ '_multiprocessing/multiprocessing.c', + '_multiprocessing/semaphore.c', + '_multiprocessing/pipe_connection.c', + '_multiprocessing/socket_connection.c', + '_multiprocessing/win32_functions.c' + ] + + else: + multiprocessing_srcs = [ '_multiprocessing/multiprocessing.c', + '_multiprocessing/socket_connection.c' + ] + + if macros.get('HAVE_SEM_OPEN', False): + multiprocessing_srcs.append('_multiprocessing/semaphore.c') + + exts.append ( Extension('_multiprocessing', multiprocessing_srcs, + define_macros=list(macros.items()), + include_dirs=["Modules/_multiprocessing"])) + # End multiprocessing It defined variable `libraries' and assigned it according to host_platform, but forgot to pass it to Extension. So we should correct it, and add `-lpthread' for linux. |
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msg334351 - (view) | Author: Barry Davis (Barry Davis) | Date: 2019-01-25 10:50 | |
I've just hit this issue using Python-2.7.9, gcc-8.1.0, glibc-2.23. The patch I made to fix the issue based on comments in this issue: --- Python-2.7.9/setup.py 2019-01-25 09:30:39.049501423 +0000 +++ Python-2.7.9/setup.py 2019-01-25 09:30:55.369609646 +0000 @@ -1670,7 +1670,7 @@ else: # Linux and other unices macros = dict() - libraries = ['rt'] + libraries = ['rt', 'pthread'] if host_platform == 'win32': multiprocessing_srcs = [ '_multiprocessing/multiprocessing.c', @@ -1690,6 +1690,7 @@ if sysconfig.get_config_var('WITH_THREAD'): exts.append ( Extension('_multiprocessing', multiprocessing_srcs, + libraries = libraries, define_macros=macros.items(), include_dirs=["Modules/_multiprocessing"])) else: |
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msg334352 - (view) | Author: Barry Davis (Barry Davis) | Date: 2019-01-25 10:58 | |
The behaviour I saw (32-bit only) was a python process getting stuck. I got this from strace: ... futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) futex(0xb5acc000, FUTEX_WAIT, 0, NULL) = -1 EAGAIN (Resource temporarily unavailable) ... And this from gdb: (gdb) bt #0 0xb76fbc5d in __kernel_vsyscall () #1 0xb74af2a4 in sem_wait () from /lib/libpthread.so.0 #2 0xb69a5429 in ?? () from /usr/lib/python2.7/lib-dynload/_multiprocessing.so #3 0xb75a262e in call_function (oparg=<optimized out>, pp_stack=0xbfb7f038) at Python/ceval.c:4033 #4 PyEval_EvalFrameEx (f=<optimized out>, throwflag=<optimized out>) at Python/ceval.c:2679 #5 0xb75a2f7d in PyEval_EvalCodeEx (co=<optimized out>, globals= {'Queue': <type at remote 0xb69c43dc>, 'atexit': <module at remote 0xb6d369bc>, 'Semaphore': <type at remote 0xb69b978c>, 'Empty': <type at remote 0xb69b902c>, 'Full': <type at remote 0xb69b9204>, 'SimpleQueue': <type at remote 0xb69c478c>, 'assert_spawning': <function at remote 0xb69ba684>, '__all__': ['Queue', 'SimpleQueue', 'JoinableQueue'], '_multiprocessing': <module at remote 0xb6c16944>, '_sentinel': <object at remote 0xb726f4d0>, '__package__': 'multiprocessing', 'collections': <module at remote 0xb71bce3c>, '__doc__': None, 'Condition': <type at remote 0xb69c402c>, 'JoinableQueue': <type at remote 0xb69c45b4>, '__builtins__': {'bytearray': <type at remote 0xb76c27e0>, 'IndexError': <type at remote 0xb76c6900>, 'all': <built-in function all>, 'help': <_Helper at remote 0xb71f824c>, 'vars': <built-in function vars>, 'SyntaxError': <type at remote 0xb76c6c80>, 'unicode': <type at remote 0xb76d6c00>, 'UnicodeDecodeError': <type at remote 0xb76c6420>, 'memoryview': <type at remote 0xb76cdda0>, 'isinstance...(truncated), locals=0x0, args=0xb535f5cc, argcount=2, kws=0xb535f5d4, kwcount=0, defs=0xb69b6058, defcount=2, closure=0x0) at Python/ceval.c:3265 #6 0xb75a0f3d in fast_function (nk=0, na=<optimized out>, n=2, pp_stack=0xbfb7f178, func=<function at remote 0xb69c51b4>) at Python/ceval.c:4129 #7 call_function (oparg=<optimized out>, pp_stack=0xbfb7f178) at Python/ceval.c:4054 #8 PyEval_EvalFrameEx (f=<optimized out>, throwflag=<optimized out>) at Python/ceval.c:2679 ... (gdb) py-bt #4 Frame 0xb536602c, for file /usr/lib/python2.7/multiprocessing/queues.py, line 101, in put (self=<Queue(_writer=<_multiprocessing.Connection at remote 0x96878c8>, _recv=<built-in method recv of _multiprocessing.Connection object at remote 0x967ddc8>, _thread=None, _sem=<BoundedSemaphore(release=<built-in method release of _multiprocessing.SemLock object at remote 0xb53427c0>, acquire=<built-in method acquire of _multiprocessing.SemLock object at remote 0xb53427c0>, _semlock=<_multiprocessing.SemLock at remote 0xb53427c0>) at remote 0xb53425cc>, _buffer=<collections.deque at remote 0xb533f844>, _closed=False, _send=<built-in method send of _multiprocessing.Connection object at remote 0x96878c8>, _jointhread=None, _reader=None, _opid=3752, _rlock=<Lock(release=<built-in method release of _multiprocessing.SemLock object at remote 0xb5342420>, acquire=<built-in method acquire of _multiprocessing.SemLock object at remote 0xb5342420>, _semlock=<_multiprocessing.SemLock at remote 0xb5342420>) at remote 0xb534240c>, _...(truncated) ... |
History | |||
---|---|---|---|
Date | User | Action | Args |
2022-04-11 14:58:49 | admin | set | github: 75354 |
2019-05-16 03:15:00 | hongxu | set | pull_requests: + pull_request13264 |
2019-01-25 10:58:47 | Barry Davis | set | messages: + msg334352 |
2019-01-25 10:50:04 | Barry Davis | set | nosy:
+ Barry Davis messages: + msg334351 |
2018-11-26 21:18:03 | pablogsal | set | nosy:
+ pitrou, benjamin.peterson |
2018-11-16 07:39:25 | hongxu | set | pull_requests: + pull_request9812 |
2018-11-16 07:33:04 | hongxu | set | pull_requests: - pull_request9808 |
2018-11-16 07:32:56 | hongxu | set | pull_requests: - pull_request9809 |
2018-11-16 07:31:54 | hongxu | set | pull_requests: + pull_request9810 |
2018-11-16 07:20:43 | hongxu | set | pull_requests: + pull_request9809 |
2018-11-16 07:19:23 | hongxu | set | pull_requests: - pull_request3087 |
2018-11-16 07:19:05 | hongxu | set | keywords:
+ patch stage: patch review pull_requests: + pull_request9808 |
2017-08-10 07:37:01 | hongxu | set | pull_requests: + pull_request3087 |
2017-08-10 07:23:39 | hongxu | set | messages: + msg300054 |
2017-08-10 07:22:33 | hongxu | set | messages: + msg300053 |
2017-08-10 07:21:56 | hongxu | create |