[HBASE-4367] Deadlock in MemStore flusher due to JDK internally synchronizing on current thread

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 0.90.4
• Fix Version/s: 0.92.0
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 10/Sep/11 08:13
• Updated: 28/May/20 19:58
• Resolved: 25/Oct/11 07:39

Description

We observed a deadlock in production between the following threads:

• IPC handler thread holding the monitor lock on MemStoreFlusher inside reclaimMemStoreMemory, waiting to obtain MemStoreFlusher.lock (the reentrant lock member)
• cacheFlusher thread inside flushRegion holds MemStoreFlusher.lock, and then calls PriorityCompactionQueue.add, which calls PriorityCompactionQueue.addToRegionsInQueue, which calls CompactionRequest.toString(), which calls Date.toString. If this occurs just after a GC under memory pressure, Date.toString needs to reload locale information (stored in a soft reference), so it calls ResourceBundle.loadBundle, which uses Thread.currentThread() as a synchronizer (see sun bug http://bugs.sun.com/view_bug.do?bug_id=6915621). Since the current thread is the MemStoreFlusher itself, we have a lock order inversion and a deadlock.

Issue Links

• is related to: HBASE-24451 Remove the HasThread because the related bug had been fixed since jdk7