[SOLR-14635] improve ThreadDumpHandler to show more info related to locks

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 8.7, master (9.0)
• Assignee: Chris M. Hostetter
• Reporter: Chris M. Hostetter
• Created: 07/Jul/20 18:07
• Updated: 04/Nov/20 15:21
• Resolved: 16/Jul/20 22:08

Description

Having recently spent some time trying to use ThreadDumpHandler to diagnose a "lock leak" i realized there are quite a few bits of info available from the ThreadMXBean/ThreadInfo datastcutures that are not included in the response, and i think we should add them:

• switch from findMonitorDeadlockedThreads() to findDeadlockedThreads() to also detect deadlocks from ownable syncrhonizers (ie: ReintrantLocks)
• for each thread:
  • in addition to outputing the current getLockName() when a thread is blocked/waiting, return info about the lock owner when available.
    • there's already dead code checking this and then throwing away the info
  • return the list of all locks (both monitors and ownable synchronizers) held by each thread