I'm filing this as a follow-up to bug 746946. We landed a band-aid patch there, but a real solution involves finding out why this is happening, and perhaps using GeckoAsyncTask instead of AsyncTask to ensure onPostExecute always gets run on the main thread. However, to make this switch, we'd need to implement cancel() for GeckoAsyncTask.
Created attachment 639931 [details] [diff] [review] debug patch I just ran into this after landing patches in bug 769145. Here's the STR I'm using - they only seem to work on my Galaxy Nexus: 1) Go to Manage Applications > Fennec, and click "Clear data" 2) Open Fennec 3) Quickly tap the AwesomeBar 4) Wait a few seconds 5) If there's no crash, click back, then go to step 3 (if the favicon on about:home has loaded, it's too late; start over from step 1) This crashes fairly reliably for me with the signature from bug 746946. I followed these STR using the attached patch, and here's the output I see when it crashes: D/BRN ( 1056): 1 calling from main thread? true D/BRN ( 1056): 2 calling from main thread? false D/BRN ( 1056): 3 calling from main thread? false This seems like a bug in AsyncTask since, according to , onPostExecute() should be called on same thread as the AsyncTask (which is the UI thread here). This led me to , which validates that it is, in fact, a recognized Android bug. I tried the solution given by romainguy, and it fixes the problem.  http://developer.android.com/reference/android/os/AsyncTask.html  http://code.google.com/p/android/issues/detail?id=20915
Created attachment 639933 [details] [diff] [review] patch Here's the suggested fix. Hopefully this fixes other similar bugs.
(In reply to Brian Nicholson (:bnicholson) from comment #1) > I just ran into this after landing patches in bug 769145. Here's the STR I'm > using - they only seem to work on my Galaxy Nexus: s/Galaxy Nexus/Galaxy S/ This is the same phone, and very similar steps, to what Aaron used to reproduce bug 769145.
Comment on attachment 639933 [details] [diff] [review] patch Shouldn't this be in GeckoApplication instead of GeckoActivity? See: http://code.google.com/p/android/issues/detail?id=20915#c7
Comment on attachment 639933 [details] [diff] [review] patch As Finkle said in comment 4, this should be done in Application::onCreate(). I'd also note that this doesn't guaranty to work around the problem, just makes it much less likely that we'll hit it. The sure fire way to fix this is to stop using AsyncTasks and use GeckoAsyncTasks.
(In reply to Brad Lassey [:blassey] from comment #5) > The sure fire way to fix this is to stop using AsyncTasks and use GeckoAsyncTasks. I think we needed a few more features in GeckoAsyncTask to be able to use it in more places.
Created attachment 639935 [details] [diff] [review] patch v2 Moved to GeckoApplication
Comment on attachment 639935 [details] [diff] [review] patch v2 [Approval Request Comment] Bug caused by (feature/regressing bug #): none User impact if declined: potential to crash using AsyncTask Testing completed (on m-c, etc.): just landed on inbound Risk to taking this patch (and alternatives if risky): very low risk String or UUID changes made by this patch: none
Comment on attachment 639935 [details] [diff] [review] patch v2 [Triage Comment] Given the low risk profile and the mobile team's tracking-fennec designation, let's uplift to Aurora 15.