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  1. MariaDB Connector/J
  2. CONJ-1061

Many threads blocked in MariaDbStatement#executeInternal waiting on lock



    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Not a Bug
    • 2.7.2, 2.7.8
    • N/A
    • Other
    • None


      We are seeing customers thread dumps showing hundreds of threads blocked waiting on MariaDbStatement.executeInternal on line 340 (in v2.7.2) which is a lock.lock() call. Although I have no repro, I suspect somewhere the lock is not being unlocked.

      EDIT: The following paragraph talks about 2.7.2 code, which it looks like has since been patched and the code I mention is no longer in 2.7.8. Apologies, I was unaware. However, we are still seeing customers with hundreds of threads waiting on the locks in 2.7.8.
      A code inspection shows that there are finally-blocks around the code to do the unlock but there are lines of code that can throw RuntimeException before the unlock occurs, which would essentially make it so the unlock() call is not reached. For example, executeInternal's finally block calls executeEpilogue before it unlocks. Unfortunately, a subroutine, stopTimeoutTask(), calls Future#get() which throws CancellationException which is a RuntimeException and would not be caught, preventing the unlock. Additionally stopTimeoutTask() calls Thread.currentThread().interrupt() which can also throw SecurityException which is another RuntimeException.

      ASK: Please ensure that unlock() is called for all the methods that do locking. Either ensure that prior methods in the finally block cannot throw any exception or unlock first, if possible. (EDIT: perhaps this means wrapping all methods before the unlock with a try/catch since underlying methods do not need to declare any RuntimeExceptions thrown)

      Affected versions: 2.7.2 and 2.7.8 for sure, but also probably the versions in between and possibly earlier versions as well.

      Using server mariadb server v10.6.11

      Repro: None




            diego dupin Diego Dupin
            julianbui Julian Bui
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