Re: Pkgsrc python cannot import SemLock on CentOS

[Jason Bacon <outpaddling%yahoo.com@localhost>]

On 11/6/18 3:48 PM, Jason Bacon wrote:
> Anyone know how to get around this?  It's hit me a couple of times now 
> in applications I'd really
> like to deploy via pkgsrc.
>
> Yum's python imports fine, but I've seen this issue with multiple 
> versions of pkgsrc python.
>
> It's not true that the platform lacks a functioning sem_open().
>
> Thanks,
>
>     JB
>
> Pkgsrc python:
>
> Linux centosdev.ceas  bacon ~ 1019: python3.7
> Python 3.7.0 (default, Oct 15 2018, 04:47:22)
> [GCC 6.4.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import multiprocessing
> >>> from multiprocessing import synchronize
> Traceback (most recent call last):
>   File "/usr/pkg/lib/python3.7/multiprocessing/synchronize.py", line 
> 29, in <module>
>     from _multiprocessing import SemLock, sem_unlink
> ImportError: cannot import name 'SemLock' from '_multiprocessing' 
> (/usr/pkg/lib/python3.7/lib-dynload/_multiprocessing.so)
>
> During handling of the above exception, another exception occurred:
>
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/pkg/lib/python3.7/multiprocessing/synchronize.py", line 
> 33, in <module>
>     " synchronization primitives needed will not" +
> ImportError: This platform lacks a functioning sem_open 
> implementation, therefore, the required synchronization primitives 
> needed will not function, see issue 3770.
> >>>
>
> Yum python:
>
> Linux centosdev.ceas  bacon ~ 1019: /usr/bin/python
> Python 2.7.5 (default, Jul 13 2018, 13:06:57)
> [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import multiprocessing
> >>> from multiprocessing import synchronize
> >>>
>
> Linux centosdev.ceas  bacon ~ 1020: uname -a
> Linux centosdev.ceas.uwm.edu 3.10.0-693.11.1.el7.x86_64 #1 SMP Mon Dec 
> 4 23:52:40 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
> Linux centosdev.ceas  bacon ~ 1022: cat /etc/redhat-release
> CentOS Linux release 7.5.1804 (Core)
Furthermore, checking the output of "make configure" in python37:

[root@centosdev python37]# grep -i sem log
checking for library containing sem_init... -lpthread
checking for sem_open... yes
checking for sem_timedwait... yes
checking for sem_getvalue... yes
checking for sem_unlink... yes
checking for x64 gcc inline assembler... yes
checking whether we can use gcc inline assembler to get and set x87 
control word... yes
checking whether we can use gcc inline assembler to get and set mc68881 
fpcr... no
checking whether POSIX semaphores are enabled... yes
checking for broken sem_getvalue... no