[HADOOP-11499] Check of executorThreadsStarted in ValueQueue#submitRefillTask() evades lock acquisition

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.7.0
• Hadoop Flags: Reviewed
• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 22/Jan/15 00:06
• Updated: 24/Apr/15 22:48
• Resolved: 26/Jan/15 16:58

Description

    if (!executorThreadsStarted) {
      synchronized (this) {
        // To ensure all requests are first queued, make coreThreads =
        // maxThreads
        // and pre-start all the Core Threads.
        executor.prestartAllCoreThreads();
        executorThreadsStarted = true;
      }
    }

It is possible that two threads executing the above code both see executorThreadsStarted as being false, leading to executor.prestartAllCoreThreads() called twice.