svn commit: r188727 - in stable/7: sys sys/contrib/pf sys/dev/ath/ath_hal sys/dev/cxgb sys/kern sys/modules/sem sys/sys tools/regression/posixsem usr.bin/procstat

Bruce Simpson bms at
Wed Feb 18 00:18:10 PST 2009

John Baldwin wrote:
> Author: jhb
> Date: Tue Feb 17 19:57:52 2009
> New Revision: 188727
> URL:
> Log:
>   MFC: Rework the lifetime management of the kernel implementation of POSIX
>   semaphores.  Specifically, semaphores are now represented as new file
>   descriptor type that is set to close on exec.  This removes the need for
>   all of the manual process reference counting (and fork, exec, and exit
>   event handlers) as the normal file descriptor operations handle all of
>   that for us nicely.  It is also suggested as one possible implementation
>   in the spec and at least one other OS (OS X) uses this approach.

This change *may* fix Python 2.6's 'multiprocessing' module on FreeBSD 
7-STABLE, which is known to have problems there; it depends on POSIX 
semaphores to synchronize its IPC between different fork()'s of the 
Python interpreter.

If anyone else has an interest in ths they may wish to test, if not, I 
will try to get around to it eventually.


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