poky/meta/recipes-devtools/python/python3/pass-missing-libraries-to-Extension-for-mul.patch

From a784b70d47ba2104afbcfd805e2a66cdc2109ec5 Mon Sep 17 00:00:00 2001
From: Hongxu Jia <hongxu.jia@windriver.com>
Date: Fri, 4 Aug 2017 11:16:14 +0800
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: Submitted [https://github.com/python/cpython/pull/2999]

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
---
 setup.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/setup.py b/setup.py
index 4f0f522..d05707d 100644
--- a/setup.py
+++ b/setup.py
@@ -1606,8 +1606,10 @@ class PyBuildExt(build_ext):
         elif host_platform.startswith('netbsd'):
             macros = dict()
             libraries = []
-
-        else:                                   # Linux and other unices
+        elif host_platform.startswith(('linux')):
+            macros = dict()
+            libraries = ['pthread']
+        else:                                   # Other unices
             macros = dict()
             libraries = ['rt']
 
@@ -1626,6 +1628,7 @@ class PyBuildExt(build_ext):
         if sysconfig.get_config_var('WITH_THREAD'):
             exts.append ( Extension('_multiprocessing', multiprocessing_srcs,
                                     define_macros=list(macros.items()),
+                                    libraries=libraries,
                                     include_dirs=["Modules/_multiprocessing"]))
         else:
             missing.append('_multiprocessing')
-- 
2.7.4