Filed by: wkocher [at] mozilla.com https://treeherder.mozilla.org/logviewer.html#?job_id=90129010&repo=autoland https://archive.mozilla.org/pub/firefox/tinderbox-builds/autoland-win32-debug/1491829490/autoland_win7_vm-debug_test-xpcshell-bm129-tests1-windows-build527.txt.gz

I think this not a necko specific bug.

The channel ID type was changed from UUID string to uint64 in bug 1348462. Landed in m-c on 2017-04-04, this bug reported few days later, on 2017-04-10. Random coincidence or not?

Locally reproducible, there is only one task that remains in the queue: base::ObjectWatcher::Watch The whole expand of the work queue: - work_queue_ { size=1 } std::queue<MessageLoop::PendingTask,std::deque<MessageLoop::PendingTask,std::allocator<MessageLoop::PendingTask> > > + c { size=1 } std::deque<MessageLoop::PendingTask,std::allocator<MessageLoop::PendingTask> > - [Raw View] {c={ size=1 } } std::queue<MessageLoop::PendingTask,std::deque<MessageLoop::PendingTask,std::allocator<MessageLoop::PendingTask> > > - c { size=1 } std::deque<MessageLoop::PendingTask,std::allocator<MessageLoop::PendingTask> > + [allocator] allocator std::_Compressed_pair<std::_Wrap_alloc<std::allocator<MessageLoop::PendingTask> >,std::_Deque_val<std::_Deque_simple_types<MessageLoop::PendingTask> >,1> - [0] {task={mRawPtr=0x02c7c970 {watcher=0x00000000 <NULL> object=0x000005c0 wait_object=0x0bf3f990 ...} } ...} MessageLoop::PendingTask - task {mRawPtr=0x02c7c970 {watcher=0x00000000 <NULL> object=0x000005c0 wait_object=0x0bf3f990 ...} } nsCOMPtr<nsIRunnable> - mRawPtr 0x02c7c970 {watcher=0x00000000 <NULL> object=0x000005c0 wait_object=0x0bf3f990 ...} nsIRunnable * {base::ObjectWatcher::Watch} - [base::ObjectWatcher::Watch] {watcher=0x00000000 <NULL> object=0x000005c0 wait_object=0x0bf3f990 ...} base::ObjectWatcher::Watch + mozilla::Runnable {mRefCnt={mValue=1 } _mOwningThread={mThread=0x00d67290 } mName=0x195e7e8c "ObjectWatcher::Watch" } mozilla::Runnable + watcher 0x00000000 <NULL> base::ObjectWatcher * object 0x000005c0 void * wait_object 0x0bf3f990 void * + origin_loop 0x028afd70 {type_=TYPE_IO (2) id_=2 work_queue_={ size=1 } ...} MessageLoop * + delegate 0x00d5edd4 {...} base::ObjectWatcher::Delegate * did_signal true bool + nsISupports {...} nsISupports + delayed_run_time {ticks_=0 } base::TimeTicks sequence_num 0 int nestable true bool + [Raw View] {...} std::deque<MessageLoop::PendingTask,std::allocator<MessageLoop::PendingTask> >

(Note: we should duplicate all "MessageLoop::DeletePendingTasks" crash bugs to this one)

Carrying ni from bug 1338878 here.

Note that there has been some more investigation done in bug 1380530.

It looks like this might have stopped (presumably because of bug 1380530).