Keith Turner created CURATOR-468:
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Summary: 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
Closing a a leader selector seems to always log spurious error messages. This
only happens when it has assumed leader 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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