From bad7e6a625436402a01d03021fb9ccd58bc9930f Mon Sep 17 00:00:00 2001
From: Alexander Kanavin <alex.kanavin@gmail.com>
Date: Thu, 9 Jan 2020 17:44:05 +0100
Subject: [PATCH] setup.py: pass missing libraries to Extension for
 multiprocessing module

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
...
(see diff in setup.py)
It assigned libraries for multiprocessing module according
the host_platform, but not pass it to Extension.

In glibc, the following commit caused two definition of
sem_getvalue are different.
https://sourceware.org/git/?p=glibc.git;a=commit;h=042e1521c794a945edc43b5bfa7e69ad70420524
(see diff in nptl/sem_getvalue.c for detail)
`__new_sem_getvalue' is the latest sem_getvalue@@GLIBC_2.1
and `__old_sem_getvalue' is to compat the old version
sem_getvalue@GLIBC_2.0.

To build python for embedded Linux systems:
http://www.yoctoproject.org/docs/2.3.1/yocto-project-qs/yocto-project-qs.html
If not explicitly link to library pthread (-lpthread), it will
load glibc's sem_getvalue randomly at runtime.

Such as build python on linux x86_64 host and run the python
on linux x86_32 target. If not link library pthread, it caused
multiprocessing bounded semaphore could not work correctly.
...
>>> import multiprocessing
>>> pool_sema = multiprocessing.BoundedSemaphore(value=1)
>>> pool_sema.acquire()
True
>>> pool_sema.release()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: semaphore or lock released too many times
...

And the semaphore issue also caused multiprocessing.Queue().put() hung.

Upstream-Status: Pending

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>

---
 setup.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.py b/setup.py
index d92face..f42bcbb 100644
--- a/setup.py
+++ b/setup.py
@@ -1836,7 +1836,7 @@ class PyBuildExt(build_ext):
             if (sysconfig.get_config_var('HAVE_SEM_OPEN') and not
                 sysconfig.get_config_var('POSIX_SEMAPHORES_NOT_ENABLED')):
                 multiprocessing_srcs.append('_multiprocessing/semaphore.c')
-        self.add(Extension('_multiprocessing', multiprocessing_srcs,
+        self.add(Extension('_multiprocessing', multiprocessing_srcs, libraries=['pthread'],
                            include_dirs=["Modules/_multiprocessing"]))
 
         if (not MS_WINDOWS and