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https://issues.apache.org/jira/browse/CURATOR-468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16502234#comment-16502234
]
Keith Turner commented on CURATOR-468:
--------------------------------------
bq. Alternatively, I guess we could clear the interrupted flag, clean up and
then reset the flag, but I think that this is going to be more error prone.
I am not completely sure about that approach either. The code would look
something like the following.
{code:java}
hasLeadership = false;
// The following clears and returns the interrupt status. One reason a
// thread may be here is because it was interrupted. However the interrupt
// being set will cause releasing the mutex to fail, so clear the interrupt
// status.
boolean wasInterruped = Thread.currentThread().interrupted();
try
{
mutex.release();
}
catch ( Exception e )
{
ThreadUtils.checkInterrupted(e);
log.error("The leader threw an exception", e);
// ignore errors - this is just a safety
} finally {
if(wasInterruped) {
Thread.currentThread().interrupt();
}
}
{code}
> Closing an active leader selector always logs spurious error
> ------------------------------------------------------------
>
> Key: CURATOR-468
> URL: https://issues.apache.org/jira/browse/CURATOR-468
> Project: Apache Curator
> Issue Type: Improvement
> Reporter: Keith Turner
> Assignee: Jordan Zimmerman
> Priority: Major
>
> Closing a a leader selector seems to always log spurious error messages.
> This only happens when it has assumed leadership because of CURATOR-337. I
> think this spurious error logging highlights a conceptual problem with the
> code. The primary reason that [LeaderSelector.java line
> 449|https://github.com/apache/curator/blob/ee5d65463b73abb2a2b732fb02729239b183519d/curator-recipes/src/main/java/org/apache/curator/framework/recipes/leader/LeaderSelector.java#L449]
> is executed is because the thread was interrupted. Since the interrupt is
> set for the thread the call to release the mutex will never work, so its a
> bit of a catch-22.
> Below is an example of the exception I am seeing.
> {noformat}
> 2018-05-31 20:23:51,068 [leader.LeaderSelector] ERROR: The leader threw an
> exception
> java.lang.InterruptedException
> at java.lang.Object.wait(Native Method)
> at java.lang.Object.wait(Object.java:502)
> at org.apache.zookeeper.ClientCnxn.submitRequest(ClientCnxn.java:1406)
> at org.apache.zookeeper.ZooKeeper.delete(ZooKeeper.java:871)
> at
> org.apache.curator.framework.imps.DeleteBuilderImpl$5.call(DeleteBuilderImpl.java:250)
> at
> org.apache.curator.framework.imps.DeleteBuilderImpl$5.call(DeleteBuilderImpl.java:244)
> at org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:109)
> at
> org.apache.curator.framework.imps.DeleteBuilderImpl.pathInForeground(DeleteBuilderImpl.java:241)
> at
> org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:225)
> at
> org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:35)
> at
> org.apache.curator.framework.recipes.locks.LockInternals.deleteOurPath(LockInternals.java:339)
> at
> org.apache.curator.framework.recipes.locks.LockInternals.releaseLock(LockInternals.java:123)
> at
> org.apache.curator.framework.recipes.locks.InterProcessMutex.release(InterProcessMutex.java:154)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.doWork(LeaderSelector.java:449)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.doWorkLoop(LeaderSelector.java:466)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.access$100(LeaderSelector.java:65)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:246)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:240)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> {noformat}
> Below is an example of an exception I see when closing a leader selector and
> then closing the curator framework.
> {noformat}
> 2018-05-31 20:23:49,905 [leader.LeaderSelector] ERROR: The leader threw an
> exception
> java.lang.IllegalStateException: instance must be started before calling this
> method
> at
> org.apache.curator.shaded.com.google.common.base.Preconditions.checkState(Preconditions.java:176)
> at
> org.apache.curator.framework.imps.CuratorFrameworkImpl.delete(CuratorFrameworkImpl.java:359)
> at
> org.apache.curator.framework.recipes.locks.LockInternals.deleteOurPath(LockInternals.java:339)
> at
> org.apache.curator.framework.recipes.locks.LockInternals.releaseLock(LockInternals.java:123)
> at
> org.apache.curator.framework.recipes.locks.InterProcessMutex.release(InterProcessMutex.java:154)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.doWork(LeaderSelector.java:449)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.doWorkLoop(LeaderSelector.java:466)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector.access$100(LeaderSelector.java:65)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:246)
> at
> org.apache.curator.framework.recipes.leader.LeaderSelector$2.call(LeaderSelector.java:240)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> {noformat}
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