Re: Threads + Garbage Collection = Crash?
Re: Threads + Garbage Collection = Crash?
- Subject: Re: Threads + Garbage Collection = Crash?
- From: Bill Bumgarner <email@hidden>
- Date: Thu, 02 Oct 2008 10:28:13 -0700
On Oct 1, 2008, at 9:17 AM, Ashley Clark wrote:
As for your crashes I think I can offer some advice. If you're not
doing
any mallocs then most likely you're passing objects back to your main
thread through some shared space, possibly via contextInfo:
Yes -- this can be a problem. If the contextInfo of an object is a
stored in a (void *) instance variable, then the collector will not
scan that iVar and will not that field as a reference to the object.
You can use CFRetain/CFRelease to prevent collection when a reference
to the object is stored into an unscanned location.
I've seen in my own GC programs using threads that occasionally the
collector (usually during high object usage) will collect objects
that are
in transit unless you CFRetain them in your thread before sending
and then
CFRelease them in the other thread once you've assigned them to a gc-
ed
storage variable.
This should only happen if the object is only referenced by unscanned
memory. If there are references on any thread's stack, then the
collector shouldn't touch the object (assuming the thread is
registered with the collector). If you have a reproducible case where
you think the object should not be collected, but is, please file a
bug and send me the #.
b.bum
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