RE: ServerCnxnFactory startup order and registering ZooKeeperServer JMX MBean

[Rakesh R]

Hi Stevo Slavic,

Yes, its very nice observation. I think this has to be corrected.

Could you raise a JIRA ticket and add these details in that for further 
discussion.

Regards,
Rakesh

-----Original Message-----
From: Stevo Slavić [mailto:ssla...@gmail.com] 
Sent: 02 September 2014 03:08
To: user@zookeeper.apache.org
Subject: ServerCnxnFactory startup order and registering ZooKeeperServer JMX 
MBean

Hello ZooKeeper community,

When running ZK (3.4.6) related tests in parallel in same JVM, multiple servers 
although assigned a different local port clash when trying to register JMX 
MBean for server (see [1]) - the two get assigned same MBean name. Registering 
JMX MBean for ZooKeeperServer it seems cannot be disabled, not even for tests.

Looking into ZooKeeperServerBean constructor, and ZooKeeperServer.getClientPort 
one can see that the MBean name will clash only when server connection factory 
is not bound to server, before startup method of server connection factory gets 
called.
This is exactly what happens in startup methods of both NIOServerCnxnFactory 
and NettyServerCnxnFactory, because of IMO wrong order that the methods are 
being called. Instead of current [2] IMO it should be [3] or at least [4].

Is my understanding wrong? If not, is this a (known) bug?

Kind regards,
Stevo Slavic


[1] example build output fragment with failing ZK server JMX MBean registration
javax.management.InstanceAlreadyExistsException:
org.apache.ZooKeeperService:name0=StandaloneServer_port-1
        at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:437)
        at
com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerWithRepository(DefaultMBeanServerInterceptor.java:1898)
        at
com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:966)
        at
com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:900)
        at
com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:324)
        at
com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
        at
org.apache.zookeeper.jmx.MBeanRegistry.register(MBeanRegistry.java:96)
        at
org.apache.zookeeper.server.ZooKeeperServer.registerJMX(ZooKeeperServer.java:377)
        at
org.apache.zookeeper.server.ZooKeeperServer.startup(ZooKeeperServer.java:410)
        at
org.apache.zookeeper.server.NIOServerCnxnFactory.startup(NIOServerCnxnFactory.java:123)



[2]
    @Override
    public void startup(ZooKeeperServer zks) throws IOException,
            InterruptedException {
        start();
        zks.startdata();
        zks.startup();
        setZooKeeperServer(zks);
    }

[3]
    @Override
    public void startup(ZooKeeperServer zks) throws IOException,
            InterruptedException {
        start();
        setZooKeeperServer(zks);
        zks.startdata();
        zks.startup();
    }

[4]
    @Override
    public void startup(ZooKeeperServer zks) throws IOException,
            InterruptedException {
        start();
        zks.startdata();
        setZooKeeperServer(zks);
        zks.startup();
    }