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YARN-1121. Addendum patch. Fixed AsyncDispatcher hang issue during stop due to a race condition caused by the previous patch. Contributed by Jian He. 

svn merge --ignore-ancestry -c 1554344 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1554345 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Vinod Kumar Vavilapalli 2013-12-31 01:10:29 +00:00
parent e81796015a
commit 5f698ffb57
1 changed files with 16 additions and 2 deletions
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18
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/event/AsyncDispatcher.java
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@ -56,6 +56,7 @@ public class AsyncDispatcher extends AbstractService implements Dispatcher {
// Indicates all the remaining dispatcher's events on stop have been drained
// and processed.
private volatile boolean drained = true;
private Object waitForDrained = new Object();
// For drainEventsOnStop enabled only, block newly coming events into the
// queue while stopping.
@ -82,6 +83,16 @@ public class AsyncDispatcher extends AbstractService implements Dispatcher {
public void run() {
while (!stopped && !Thread.currentThread().isInterrupted()) {
drained = eventQueue.isEmpty();
// blockNewEvents is only set when dispatcher is draining to stop,
// adding this check is to avoid the overhead of acquiring the lock
// and calling notify every time in the normal run of the loop.
if (blockNewEvents) {
synchronized (waitForDrained) {
if (drained) {
waitForDrained.notify();
}
}
}
Event event;
try {
event = eventQueue.take();
@ -125,8 +136,11 @@ public class AsyncDispatcher extends AbstractService implements Dispatcher {
if (drainEventsOnStop) {
blockNewEvents = true;
LOG.info("AsyncDispatcher is draining to stop, igonring any new events.");
while(!drained) {
Thread.yield();
synchronized (waitForDrained) {
while (!drained && eventHandlingThread.isAlive()) {
waitForDrained.wait(1000);
LOG.info("Waiting for AsyncDispatcher to drain.");
}
}
}
stopped = true;