[MacPorts] #45309: gimp2 @2.8.14 on 10.9 - doesn't load plug-ins

[MacPorts]

#45309: gimp2 @2.8.14 on 10.9 - doesn't load plug-ins
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  Reporter:  and.damore@…  |      Owner:  devans@…
      Type:  defect        |     Status:  assigned
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:
Resolution:                |   Keywords:
      Port:  gimp2         |
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Comment (by jeremyhu@…):

 > A very quick play with lldb breaking on dlclose() suggested that
 dlclose() was being called in that gegl path,

 Yep, I suspect that is resulting in the atfork handler getting removed
 from the process, but we still have a dangling pointer to it.  Show the
 backtrace to see who is calling dlclose().  Assuming you have debug
 symbols, it should point you to the correct line in source as well which
 will be helpful.

 > so the trigger in the _atfork() might be something else.

 I'm not really sure what you mean by this.  Can you please elaborate?

 From my analysis, we essentially have:

 1. gegl is dlopen()ed.
 2. Something in gegl or its dependencies registers a child atfork handler.
 3. Something is dlclose()d.
 4. fork() is called.
 5. The child side tries to call the atfork handler and crashes.

 This would be expected if the registered atfork handler is inside of the
 code that was dlclose()d.

 Also, if you set your optimization flags to -O0, you will avoid tail call
 optimizations, so we'll likely see the missing stack frames between:

 {{{
             frame #0: 0x00007fff92e420ff libsystem_c.dylib`pthread_atfork
             frame #1: 0x00007fff92e3bfc0 libsystem_c.dylib`pthread_once +
 87
             frame #2: 0x00007fff5fc13378
 dyld`ImageLoaderMachO::doModInitFunctions(ImageLoader::LinkContext const&)
 + 236
 }}}

 which will tell us exactly what library initializer is doing the
 pthread_atfork.

-- 
Ticket URL: <https://trac.macports.org/ticket/45309#comment:49>
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