zhangduo created HBASE-13146:
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Summary: Race Condition in ScheduledChore and ChoreService
Key: HBASE-13146
URL: https://issues.apache.org/jira/browse/HBASE-13146
Project: HBase
Issue Type: Bug
Components: regionserver
Affects Versions: 2.0.0, 1.1.0
Reporter: zhangduo
Assignee: zhangduo
Fix For: 2.0.0, 1.1.0
Here is my findings when addressing HBASE-13145.
{code:title=ChoreService.java}
public synchronized boolean scheduleChore(ScheduledChore chore) {
...
ScheduledFuture<?> future =
scheduler.scheduleAtFixedRate(chore, chore.getInitialDelay(),
chore.getPeriod(),
chore.getTimeUnit());
chore.setChoreServicer(this);
...
}
{code}
So we schedule the chore first, and then set chore servicer. And for
CompactionChecker, the initialDelay is 0, so it is possible that the chore is
run before we set chore servicer for it. And see this
{code:title=ScheduledChore.java}
public void run() {
...
else if (stopper.isStopped() || !isScheduled()) {
cancel(false);
cleanup();
if (LOG.isInfoEnabled()) LOG.info("Chore: " + getName() + " was stopped");
}
...
}
...
public synchronized boolean isScheduled() {
return choreServicer != null && choreServicer.isChoreScheduled(this);
}
{code}
So it is possible that isScheduled() returns false and we start to cancel the
chore. You can insert a sleep between scheduled chore and set chore servicer,
then you can always get the log ' Chore: CompactionChecker was stopped'. But it
does not always actually cancel the chore because the cancel method's
implementation.
{code:title=ScheduledChore.java}
public synchronized void cancel(boolean mayInterruptIfRunning) {
if (isScheduled()) choreServicer.cancelChore(this, mayInterruptIfRunning);
choreServicer = null;
}
{code}
So if you insert a sleep before cancel(remember to set a larger sleep time
here), then you can make the test always fail.
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