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From ruxing bao <brxonl...@hotmail.com>
Subject RE: Illegal access: this web application instance has been stopped already and NoClassDefFoundError
Date Tue, 11 Jun 2013 05:05:21 GMT
Hi  Chris,
 

> Date: Mon, 10 Jun 2013 10:18:10 -0400
> From: chris@christopherschultz.net
> To: users@tomcat.apache.org
> Subject: Re: Illegal access: this web application instance has been stopped already and
NoClassDefFoundError
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> Bob,
> 
> On 6/8/13 11:14 PM, ruxing bao wrote:
> > I'am using Zookeeper client API in java web application.When I shut
> > down tomcat,I am getting this error :
> > 
> > 
> > 
> > 2013-06-07 12:01:29,676 ERROR [org.apache.zookeeper.ClientCnxn]
> > (xxx-startStop-1-SendThread(xxx.net:12183)) from
> > xxx-startStop-1-SendThread(xxx.net:12183) 
> > java.lang.NoClassDefFoundError:
> > org/apache/zookeeper/server/ZooTrace at
> > org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1115)
> >
> > 
> Caused by: java.lang.ClassNotFoundException:
> org.apache.zookeeper.server.ZooTrace
> > at
> > org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)
> >
> > 
> at
> org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
> > ... 1 more
> > 
> > 
> > 
> > 
> > at the same time,the following is also in catalina.out:
> > 
> > 
> > 
> > INFO: Illegal access: this web application instance has been
> > stopped already. Could not load
> > org.apache.zookeeper.server.ZooTrace. The eventual following stack
> > trace is caused by an error thrown for debugging purposes as well
> > as to attempt to terminate the thread which caused the illegal
> > access, and has no functional impact. 
> > java.lang.IllegalStateException at
> > org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1597)
> >
> > 
> at
> org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
> > at
> > org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1115)
> >
> > 
> > 
> > 
> > I searched google and mail list ,couldn't find any solution,please
> > help me.
> > 
> > 
> > Enviroment info:
> > 
> > JDK:1.6.0_45
> > 
> > Tomcat:7.0.40
> > 
> > Zookeeper:3.4.5
> 
> Can you give us any more of the stack trace? It looks like this is
> happening during shutdown, but all the ServletContextListeners should
> complete before the WebappClassLoader starts shedding its loaded classes.
> 
> Are you explicitly shutting-down the ClientCnxn thread in a SCL's
> destroy() method? If not, you need to do that.
> 

Sorry,I can't get any more of the stack trace.
 
We wrapped zookeepr client as a spring bean and invoked  method "close" of zookeeper  in 
"destory-method" of bean,in that method "close",zookeeper Send Thread was closed.
When tomcat was shut down, Spring closed it's container and bean was detroyed, then "destroy-method"
of bean was invoked.
I'am confusing why is Send Thread of Zookeeper  seemed to exit slower than  the WebappClassLoader
shedding its loaded classes. 
 
ps: details of zookeeper closing
org.apache.zookeeper.Zookeeper
 public synchronized void close() throws InterruptedException {
        if (!cnxn.getState().isAlive()) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("Close called on already closed client");
            }
            return;
        }
        if (LOG.isDebugEnabled()) {
            LOG.debug("Closing session: 0x" + Long.toHexString(getSessionId()));
        }
        try {
            cnxn.close();
        } catch (IOException e) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("Ignoring unexpected exception during close", e);
            }
        }
        LOG.info("Session: 0x" + Long.toHexString(getSessionId()) + " closed");
    }
----------------------------------------------------------------------------------------------------------------------
org.apache.zookeeper.ClientCnxn
 public void close() throws IOException {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Closing client for session: 0x"
                      + Long.toHexString(getSessionId()));
        }
        try {
            RequestHeader h = new RequestHeader();
            h.setType(ZooDefs.OpCode.closeSession);
            submitRequest(h, null, null, null);
        } catch (InterruptedException e) {
            // ignore, close the send/event threads
        } finally {
            disconnect();
        }
    }
 
 
 public void disconnect() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Disconnecting client for session: 0x"
                      + Long.toHexString(getSessionId()));
        }
        sendThread.close();
        eventThread.queueEventOfDeath();
    }
-------------------------------------------------------------------------------------------------
 

org.apache.zookeeper.ClientCnxn.SendThread
 void close() {
            state = States.CLOSED;
            clientCnxnSocket.wakeupCnxn();
        }
 
 
        @Override
        public void run() {
            clientCnxnSocket.introduce(this,sessionId);
            clientCnxnSocket.updateNow();
            clientCnxnSocket.updateLastSendAndHeard();
            int to;
            long lastPingRwServer = System.currentTimeMillis();
            while (state.isAlive()) {
                try {
                    if (!clientCnxnSocket.isConnected()) {
                        if(!isFirstConnect){
                            try {
                                Thread.sleep(r.nextInt(1000));
                            } catch (InterruptedException e) {
                                LOG.warn("Unexpected exception", e);
                            }
                        }
                        // don't re-establish connection if we are closing
                        if (closing || !state.isAlive()) {
                            break;
                        }
                        startConnect();
                        clientCnxnSocket.updateLastSendAndHeard();
                    }
                    if (state.isConnected()) {
                        // determine whether we need to send an AuthFailed event.
                        if (zooKeeperSaslClient != null) {
                            boolean sendAuthEvent = false;
                            if (zooKeeperSaslClient.getSaslState() == ZooKeeperSaslClient.SaslState.INITIAL)
{
                                try {
                                    zooKeeperSaslClient.initialize(ClientCnxn.this);
                                } catch (SaslException e) {
                                   LOG.error("SASL authentication with Zookeeper Quorum member
failed: " + e);
                                    state = States.AUTH_FAILED;
                                    sendAuthEvent = true;
                                }
                            }
                            KeeperState authState = zooKeeperSaslClient.getKeeperState();
                            if (authState != null) {
                                if (authState == KeeperState.AuthFailed) {
                                    // An authentication error occurred during authentication
with the Zookeeper Server.
                                    state = States.AUTH_FAILED;
                                    sendAuthEvent = true;
                                } else {
                                    if (authState == KeeperState.SaslAuthenticated) {
                                        sendAuthEvent = true;
                                    }
                                }
                            }
                            if (sendAuthEvent == true) {
                                eventThread.queueEvent(new WatchedEvent(
                                      Watcher.Event.EventType.None,
                                      authState,null));
                            }
                        }
                        to = readTimeout - clientCnxnSocket.getIdleRecv();
                    } else {
                        to = connectTimeout - clientCnxnSocket.getIdleRecv();
                    }
                    
                    if (to <= 0) {
                        throw new SessionTimeoutException(
                                "Client session timed out, have not heard from server in "
                                        + clientCnxnSocket.getIdleRecv() + "ms"
                                        + " for sessionid 0x"
                                        + Long.toHexString(sessionId));
                    }
                    if (state.isConnected()) {
                        int timeToNextPing = readTimeout / 2
                                - clientCnxnSocket.getIdleSend();
                        if (timeToNextPing <= 0) {
                            sendPing();
                            clientCnxnSocket.updateLastSend();
                        } else {
                            if (timeToNextPing < to) {
                                to = timeToNextPing;
                            }
                        }
                    }
                    // If we are in read-only mode, seek for read/write server
                    if (state == States.CONNECTEDREADONLY) {
                        long now = System.currentTimeMillis();
                        int idlePingRwServer = (int) (now - lastPingRwServer);
                        if (idlePingRwServer >= pingRwTimeout) {
                            lastPingRwServer = now;
                            idlePingRwServer = 0;
                            pingRwTimeout =
                                Math.min(2*pingRwTimeout, maxPingRwTimeout);
                            pingRwServer();
                        }
                        to = Math.min(to, pingRwTimeout - idlePingRwServer);
                    }
                    clientCnxnSocket.doTransport(to, pendingQueue, outgoingQueue, ClientCnxn.this);
                } catch (Throwable e) {
                    if (closing) {
                        if (LOG.isDebugEnabled()) {
                            // closing so this is expected
                            LOG.debug("An exception was thrown while closing send thread for
session 0x"
                                    + Long.toHexString(getSessionId())
                                    + " : " + e.getMessage());
                        }
                        break;
                    } else {
                        // this is ugly, you have a better way speak up
                        if (e instanceof SessionExpiredException) {
                            LOG.info(e.getMessage() + ", closing socket connection");
                        } else if (e instanceof SessionTimeoutException) {
                            LOG.info(e.getMessage() + RETRY_CONN_MSG);
                        } else if (e instanceof EndOfStreamException) {
                            LOG.info(e.getMessage() + RETRY_CONN_MSG);
                        } else if (e instanceof RWServerFoundException) {
                            LOG.info(e.getMessage());
                        } else {
                            LOG.warn(
                                    "Session 0x"
                                            + Long.toHexString(getSessionId())
                                            + " for server "
                                            + clientCnxnSocket.getRemoteSocketAddress()
                                            + ", unexpected error"
                                            + RETRY_CONN_MSG, e);
                        }
                        cleanup();
                        if (state.isAlive()) {
                            eventThread.queueEvent(new WatchedEvent(
                                    Event.EventType.None,
                                    Event.KeeperState.Disconnected,
                                    null));
                        }
                        clientCnxnSocket.updateNow();
                        clientCnxnSocket.updateLastSendAndHeard();
                    }
                }
            }
            cleanup();
            clientCnxnSocket.close();
            if (state.isAlive()) {
                eventThread.queueEvent(new WatchedEvent(Event.EventType.None,
                        Event.KeeperState.Disconnected, null));
            }
            ZooTrace.logTraceMessage(LOG, ZooTrace.getTextTraceLevel(),
                                     "SendThread exitedloop.");//at this line, error occurs.
        }
--------------------------------------------------------------------------------------------------------------
 
Regards,
Bob

 
 
 
 
  		 	   		  
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