Bug 434716

Summary:	dev-lang/python:2.7 - POSIX_SEMAPHORES_NOT_ENABLED 1 in /usr/include/python2.7/pyconfig.h
Product:	Gentoo Linux	Reporter:	Andreas Nüßlein <nutz>
Component:	[OLD] Development	Assignee:	Python Gentoo Team <python>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	Normal
Version:	unspecified
Hardware:	AMD64
OS:	Linux
See Also:	https://bugs.gentoo.org/show_bug.cgi?id=496328
Whiteboard:
Package list:		Runtime testing required:	---

Description Andreas Nüßlein 2012-09-11 10:09:59 UTC

Recently I ran into a problem, when trying to install dev-python/billiard . 
It said something about semaphores not being available on my system
As +Samuele Santi pointed out, one could uncomment the line 
#define POSIX_SEMAPHORES_NOT_ENABLED 1
in /usr/include/python2.7/pyconfig.h

Funny enough, reinstalling python:2.7 also turned this line into
/* #undef POSIX_SEMAPHORES_NOT_ENABLED */

Ergo: it's enough to re-merge python:2.7, but we thought it's worth mentioning to developers and others who run into this bug.

Reproducible: Always

Steps to Reproduce:
1. Have a somewhat recent build of Gentoo (amd64) with python:2.7
2. Try to merge dev-python/billiard 

Actual Results:  
SEM_HANDLE not defined or something like that.

Expected Results:  
happy merge

Comment 1 Tully Gray 2013-05-15 19:03:55 UTC

Just had a sandbox violation trying to build Python 3.2, the failed conftest checks for semaphores and because I did not have tmpfs mounted on /dev/shm, "sem_open" was using the only tmpfs mount which was /run.  Not sure if this is relevant here, but any extra info is good info.  =)

Comment 2 Marien Zwart (RETIRED) gentoo-dev

2013-05-16 09:16:53 UTC

I've come across this before (and so have others, see bug #462542, but I think there's at least one other that I actually commented on). The short version is that with current glibc you need to have a tmpfs mounted on /dev/shm for shared memory (and some other bits) to work. I think only more recent glibcs have the fallback described in comment #1.

For the original reporter: please check what /dev/shm is. It should be on a tmpfs, or possibly a symlink to a tmpfs.

Comment 3 Mike Gilbert gentoo-dev

2014-01-01 16:45:08 UTC

I added a check to src_configure for this. See bug 496328.