[BOOKKEEPER-1065] OrderedSafeExecutor should only have 1 thread per bucket

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Fix Version/s: 4.5.0
• Assignee: Matteo Merli
• Reporter: Matteo Merli
• Created: 11/May/17 16:58
• Updated: 11/May/17 20:25
• Resolved: 11/May/17 20:25

Description

In a earlier commit, "BOOKKEEPER-874: Explict LAC from Writer to Bookie", there was this change in the OrderedSafeExecutor implementation:

         for (int i = 0; i < numThreads; i++) {
-            queues[i] = new LinkedBlockingQueue<Runnable>();
-            threads[i] =  new ThreadPoolExecutor(1, 1,
-                    0L, TimeUnit.MILLISECONDS, queues[i],
+            threads[i] =  new ScheduledThreadPoolExecutor(1,
                     new ThreadFactoryBuilder()
                         .setNameFormat(name + "-orderedsafeexecutor-" + i + "-%d")
                         .setThreadFactory(threadFactory)
                         .build());
+            threads[i].setMaximumPoolSize(1);

Then, as part of "BOOKKEEPER-1013: Fix findbugs errors on latest master", the max pool size line has been removed.

@@ -183,7 +183,6 @@ public class OrderedSafeExecutor {
                         .setNameFormat(name + "-orderedsafeexecutor-" + i + "-%d")
                         .setThreadFactory(threadFactory)
                         .build());
-            threads[i].setMaximumPoolSize(1);

             // Save thread ids
             final int idx = i;

Without that the thread pool would create multiple threads for the same bucket, breaking the ordering guarantee of the executor.

Issue Links

• links to: GitHub Pull Request #152