Bug 256283 – python 2.5.4-r2 USE=threads - ./libpython2.5.so: undefined reference to `sem_init'

• Product: Gentoo Linux
• Status: RESOLVED NEEDINFO

[Description Bernd Martin Wollny 2009-01-25 07:25:31 UTC]

It seemed that dev-lang/python-2.5.4-r2 don't add -lpthread to the LDFLAGS 

[ebuild   R   ] dev-lang/python-2.5.4-r2  USE="berkdb doc examples gdbm ipv6 ncurses readline sqlite ssl threads tk xml -build -ucs2 -wininst" 0 kB

you can build dev-lang/python-2.5.4-r2 if you set the LDFLAGS



Reproducible: Always

Steps to Reproduce:
emerge dev-lang/python [2.5.4-r2]
Actual Results:  
build fails

Expected Results:  
build python

LDFLAGS="-lpthread" emerge dev-lang/python
solves the problem

[Comment 1 Patrick Lauer 2009-01-25 07:31:30 UTC]

So what is the pthreads lib going to do with python? 
Last time I had a look the python interpreter doesn't use it, so it's a no-op as far as I can tell.

[Comment 2 Bernd Martin Wollny 2009-01-25 11:06:23 UTC]

You can use threads inside of python.
All modern languages supports threads 
see http://www.wellho.net/solutions/python-python-threads-a-first-example.html for a threading example. 

Boost-python supports threads too. 

[Comment 3 Patrick Lauer 2009-01-25 16:03:45 UTC]

The CPython interpreter is using "green" threads, which means that it looks like one thread to the rest of the OS. It does not in any way support the pthreads lib out of the box, so I don't see how randomly adding it affects anything.

[Comment 4 Bernd Martin Wollny 2009-01-26 08:13:05 UTC]

Created attachment 179750 [details]
python build log

Build without LDFLAGS="-pthreaad"

[Comment 5 Bernd Martin Wollny 2009-01-26 08:16:55 UTC]

Created attachment 179751 [details]
Build OK

this was build with LDFLAGS="-lpthread"

[Comment 6 Bernd Martin Wollny 2009-01-26 08:18:23 UTC]

Please have a look at the log files. You will see that python is using the pthread library. 

[Comment 7 Jeroen Roovers (RETIRED) 2009-01-28 17:57:36 UTC]

Please post your `emerge --info' too.

[Comment 8 Jeroen Roovers (RETIRED) 2009-01-28 18:27:07 UTC]

I don't see what could inject the acml stuff. Possibly something in CFLAGS. Meanwhile, this isn't really a major bug. With a stable system, I can compile 2.5.4-r2 fine. Please reopen this bug report with the requested information and any other information that may be key to solving this problem (note: injecting -lFOO flags into LDFLAGS is bad even as a workaround).

[Comment 9 Patrizio Bassi 2009-10-17 14:04:35 UTC]

*** Bug 288929 has been marked as a duplicate of this bug. ***

[Comment 10 Patrizio Bassi 2009-10-17 14:05:19 UTC]

for me it fails even after manually adding the pthread flag

can you please reopen?

[Comment 11 Patrizio Bassi 2009-10-28 10:05:42 UTC]

 Jeroen, Patrik,

for me this is starting to be a very blocking issue as i cannot compile any python version with threads use flag, required by several packages.

Can you reopen? i can take over and provide all info/logs/details you may been.

Thanks

[Comment 12 Patrizio Bassi 2009-10-31 11:40:25 UTC]

the error is in the configure too....

checking for poll... yes       
checking for pthread_init... no
checking for putenv... yes   


but seems not stopping so not adding the proper flags

[Comment 13 A. Wilcox (awilfox) 2015-02-28 07:54:24 UTC]

For what it's worth, I just ran in to someone having this issue wtih 2.7.9.  Tracked it down to "-fopenmp" in /etc/portage/make.conf CFLAGS.