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https://issues.apache.org/jira/browse/ZOOKEEPER-2383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15636584#comment-15636584
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Flavio Junqueira commented on ZOOKEEPER-2383:
---------------------------------------------
Moving the {{start()}} call to the end of the {{startup()}} method will cause
the change of behavior you point out, that's correct, we shouldn't do it.
Applying the test alone without the other changes still makes the test run
forever. We need to fix it.
There are a few format suggestions I wanted to make, perhaps it is better to
have a pull request for this.
> Startup race in ZooKeeperServer
> -------------------------------
>
> Key: ZOOKEEPER-2383
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2383
> Project: ZooKeeper
> Issue Type: Bug
> Components: jmx, server
> Affects Versions: 3.4.8
> Reporter: Steve Rowe
> Assignee: Rakesh R
> Priority: Blocker
> Fix For: 3.4.10, 3.5.3, 3.6.0
>
> Attachments: TestZkStandaloneJMXRegistrationRaceConcurrent.java,
> ZOOKEEPER-2383-br-3-4.patch, ZOOKEEPER-2383.patch, ZOOKEEPER-2383.patch,
> ZOOKEEPER-2383.patch, release-3.4.8-extra-logging.patch,
> zk-3.4.8-MBeanRegistry.log, zk-3.4.8-NPE.log
>
>
> In attempting to upgrade Solr's ZooKeeper dependency from 3.4.6 to 3.4.8
> (SOLR-8724) I ran into test failures where attempts to create a node in a
> newly started standalone ZooKeeperServer were failing because of an assertion
> in MBeanRegistry.
> ZooKeeperServer.startup() first sets up its request processor chain then
> registers itself in JMX, but if a connection comes in before the server's JMX
> registration happens, registration of the connection will fail because it
> trips the assertion that (effectively) its parent (the server) has already
> registered itself.
> {code:java|title=ZooKeeperServer.java}
> public synchronized void startup() {
> if (sessionTracker == null) {
> createSessionTracker();
> }
> startSessionTracker();
> setupRequestProcessors();
> registerJMX();
> state = State.RUNNING;
> notifyAll();
> }
> {code}
> {code:java|title=MBeanRegistry.java}
> public void register(ZKMBeanInfo bean, ZKMBeanInfo parent)
> throws JMException
> {
> assert bean != null;
> String path = null;
> if (parent != null) {
> path = mapBean2Path.get(parent);
> assert path != null;
> }
> {code}
> This problem appears to be new with ZK 3.4.8 - AFAIK Solr never had this
> issue with ZK 3.4.6.
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