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

John Baldwin jhb at
Wed Feb 18 07:10:59 PST 2009

On Wednesday 18 February 2009 3:18:03 am Bruce Simpson wrote:
> 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 
> >   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.
> FYI:
> 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.

When Kris tested it, it made things significantly better.  I'm not sure if it 
resolved all the issues though.

John Baldwin

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