HADOOP-11499. Check of executorThreadsStarted in ValueQueue#submitRefillTask() evades lock acquisition. Contributed by Ted Yu

(cherry picked from commit 7574df1bba33919348d3009f2578d6a81b5818e6)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -408,6 +408,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11482. Use correct UGI when KMSClientProvider is called by a proxy
     user. Contributed by Arun Suresh.
 
+    HADOOP-11499. Check of executorThreadsStarted in
+    ValueQueue#submitRefillTask() evades lock acquisition (Ted Yu via jlowe)
+
 Release 2.6.0 - 2014-11-18
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/kms/ValueQueue.java

@@ -308,11 +308,13 @@ public class ValueQueue <E> {
       final Queue<E> keyQueue) throws InterruptedException {
     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;
+        if (!executorThreadsStarted) {
+          // To ensure all requests are first queued, make coreThreads =
+          // maxThreads
+          // and pre-start all the Core Threads.
+          executor.prestartAllCoreThreads();
+          executorThreadsStarted = true;
+        }
       }
     }
     // The submit/execute method of the ThreadPoolExecutor is bypassed and