Task.TaskReporter.done method blocked for some time when task is finishing
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Key: MAPREDUCE-3612
URL: https://issues.apache.org/jira/browse/MAPREDUCE-3612
Project: Hadoop Map/Reduce
Issue Type: Bug
Reporter: Binglin Chang
We recently have done some tests to evaluate performances of different Hadoop
versions(1.0, 0.23, Baidu internal version), and found some weird results. One
of them is in 1.0 Task.TaskReporter.done() takes too much time, about 2s, this
is bad for small tasks. After reviewing source code and add some log, the
following code block Task.TaskReporter.done
src/mapred/org/apache/hadoop/mapred/Task.java
658 try {
659 Thread.sleep(PROGRESS_INTERVAL);
660 }
723 public void stopCommunicationThread() throws InterruptedException {
724 // Updating resources specified in ResourceCalculatorPlugin
725 if (pingThread != null) {
726 synchronized(lock) {
727 while(!done) {
728 lock.wait();
729 }
730 }
731 pingThread.interrupt();
732 pingThread.join();
733 }
734 }
Originally line 724-730 don't exists, I don't know why it is added. If it is
needed, we can replace Thread.sleep with Object.wait(timeout) and Object.notify
instead, so it won't block.
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