The patch that Steve Linden provided resolves the deadlock I detailed in the comments of VWR-13437.
The patch releases a mutex earlier, prior to making one of the calls that led to the deadlock. Releasing the mutex earlier eliminates that deadlock. Previously the HTTP-Texture viewer would hang on me after only a few minutes of moving my camera using Alt-Mouse. After manually applying the patch I have been unable to hang the viewer. Thank you Steve! Sheet Spotter -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steve Bennetts Sent: May 26, 2009 11:54 AM To: Second Life Developer Mailing List Subject: Re: [sldev] lltexturefetch.cpp patch for http-texture and/orsnowglobe So, adding that lock exposed a flaw in the logic resulting in a deadlock. Below is the fix for that. The problem was that LLTextureCache::update() was keeping the mutex protecting mReaders[] and mWriters[] locked while calling completed() in the responders, however readComplete() and writeComplete() (calls to which get triggered by the responders) do their own locking of the mutex, triggering the deadlock. There is no reason for the mutex to be locked while calling these completed() functions. -Steve Index: lltexturecache.cpp =================================================================== --- lltexturecache.cpp (revision 121571) +++ lltexturecache.cpp (revision 121572) @@ -779,6 +779,9 @@ } } + unlockWorkers(); + + // call 'completed' with workers list unlocked (may call readComplete() or writeComplete() for (responder_list_t::iterator iter1 = completed_list.begin(); iter1 != completed_list.end(); ++iter1) { @@ -787,8 +790,6 @@ responder->completed(success); } - unlockWorkers(); - return res; } Steve Bennetts wrote: > We will be applying this patch next week, but if someone wants to play, > I just discovered this major bug in lltexturefetch.cpp: > > void LLTextureFetchWorker::callbackDecoded(bool success, LLImageRaw* > raw, LLImageRaw* aux) > { > + LLMutexLock lock(&mWorkMutex); > > ... > > > The missing mutex lock here can cause all sorts of terrible artifacts. > Don't know if this will fix everything, but it definitely addresses at > least one of the crashes I have been seeing. > > -Steve > > > _______________________________________________ > Policies and (un)subscribe information available here: > http://wiki.secondlife.com/wiki/SLDev > Please read the policies before posting to keep unmoderated posting privileges > _______________________________________________ Policies and (un)subscribe information available here: http://wiki.secondlife.com/wiki/SLDev Please read the policies before posting to keep unmoderated posting privileges _______________________________________________ Policies and (un)subscribe information available here: http://wiki.secondlife.com/wiki/SLDev Please read the policies before posting to keep unmoderated posting privileges
