pthread_mutex_trylock and glib-2

[Coleman Kane]

Yeah, I had the same problem. Fixed it by not building with debug
code, but I noticed there was chatter about it.


On Wed, 8 Sep 2004 18:57:09 -0400, Brian Fundakowski Feldman
<green at freebsd.org> wrote:
> 
> 
> On Tue, Sep 07, 2004 at 06:27:14PM -0700, Pascal Hofstee wrote:
> > On Mon, 6 Sep 2004 15:12:08 -0700, Pascal Hofstee <caelian at gmail.com> wrote:
> > > After a few hours of digging through both the glib-2 as well as the
> > > beep-media-player sources i finally managed to figure out why
> > > beep-media-player apprently crashes on startup when using libpthread,
> > > but not when using libc_r.
> > >
> > > i filed a bugreport against this problem on bugzilla.gnome.org ... in
> > > the hope to get some feedback from glib-developers ...
> > >
> > > http://bugzilla.gnome.org/show_bug.cgi?id=152009
> > >
> > > The problem is with the actual return value of pthread_mutex_trylock
> > > returning EDEADLK instead of EBUSY.
> > >
> > > from what i have been able to glance from this previous discussion
> > > regarding this particular subject
> > > (http://lists.freebsd.org/pipermail/freebsd-threads/2004-January/001539.html)
> > >
> > > pthread_mutex_trylock should behave identical to pthread_mutex_lock
> > > except return immediately in case of a blocking mutex, which would
> > > suggest EDEADLK as a possible return value.
> > >
> > > This Seems to be the current implementation of both libpthread as well
> > > as libthr ... with libc_r being the sole exception.
> > >
> > > The pthread_mutex_trylock manpage however does not reflect this actual
> > > implementation and only mentions EBUSY and EINVAL.
> > >
> > > I was wondering assuming the implementation is actually correct if
> > > this could be rectified in the pthread_mutex_trylock manpage ... and
> > > if my assumption is wrong if the implementation could be changed to
> > > reflect the manpage.
> > >
> > > In the former case i will have to bug the glib-devs to change the
> > > implementation of their pthread_mutex_trylock wrapper ... to also
> > > check for EDEADLK.
> >
> > I am hereby including an updated
> > /usr/ports/devel/glib20/files/patch-gthread_gthread-posix.c
> >
> > that includes the additional check for EDEADLK besides EBUSY in glib's
> > g_mutex_trylock_posix_impl function.
> >
> > With this fix applied to my installation of glib beep-media-player now
> > works as expected with libpthread, and this is very likely to resolve
> > similar behaviour with other ports that try to use glib's threading
> > functions.
> >
> > I CC-ed glib20 port-maintainer (gnome at FreeBSD.org) in the hope this
> > (or appropriate alternative) fix makes it in time for 5.3-RELEASE.
> 
> FWIW, I had to fix a similar problem in mozilla/NSPR's codebase to make
> the build with debugging code turned on work.  Well, I guess it was really
> the same problem.
> 
> --
> Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
>   <> green at FreeBSD.org                               \  The Power to Serve! \
>  Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\
> 
> 
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