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  1. ActiveMQ
  2. AMQ-3844

NullPointerException when removing connection info



    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 5.4.3, 5.5.1
    • Fix Version/s: 5.6.0
    • Component/s: Broker
    • Labels:
    • Environment:

      Linux 2.6.18-274.12.1.el5 #1 SMP Tue Nov 29 13:37:35 EST 2011 i686 athlon i386 GNU/Linux, Java(TM) SE Runtime Environment (build 1.6.0_29-b11)


      Sometimes off and on the ActiveMQ server, the KahaDB maintains some old transactions that try to recovery. So at start up these transactions are added to the xaTransactions map inside TransactionBroker with a null ConnectionId.

      This is the stack trace of the recovery at startup:

      	TransactionBroker.beginTransaction(ConnectionContext, TransactionId) line: 152	
      	TransactionBroker$1.recover(XATransactionId, Message[], MessageAck[]) line: 92	
      	KahaDBTransactionStore.recover(TransactionRecoveryListener) line: 317	
      	TransactionBroker.start() line: 89	
      	BrokerService$3.start() line: 1781	
      	XBeanBrokerService(BrokerService).start() line: 489	
      	XBeanBrokerService.afterPropertiesSet() line: 60	
      	NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]	
      	NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39	
      	DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25	
      	Method.invoke(Object, Object...) line: 597	
      	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).invokeCustomInitMethod(String, Object, RootBeanDefinition) line: 1536	
      	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).invokeInitMethods(String, Object, RootBeanDefinition) line: 1477	
      	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).initializeBean(String, Object, RootBeanDefinition) line: 1409	
      	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).doCreateBean(String, RootBeanDefinition, Object[]) line: 519	
      	DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBean(String, RootBeanDefinition, Object[]) line: 456	
      	AbstractBeanFactory$1.getObject() line: 291	
      	DefaultListableBeanFactory(DefaultSingletonBeanRegistry).getSingleton(String, ObjectFactory) line: 222	
      	DefaultListableBeanFactory(AbstractBeanFactory).doGetBean(String, Class<T>, Object[], boolean) line: 288	
      	DefaultListableBeanFactory(AbstractBeanFactory).getBean(String) line: 190	
      	DefaultListableBeanFactory.preInstantiateSingletons() line: 574	
      	XBeanBrokerFactory$1(AbstractApplicationContext).finishBeanFactoryInitialization(ConfigurableListableBeanFactory) line: 895	
      	XBeanBrokerFactory$1(AbstractApplicationContext).refresh() line: 425	
      	XBeanBrokerFactory$1(ResourceXmlApplicationContext).<init>(Resource, List) line: 64	
      	XBeanBrokerFactory$1(ResourceXmlApplicationContext).<init>(Resource) line: 52	
      	XBeanBrokerFactory$1.<init>(XBeanBrokerFactory, Resource) line: 115	
      	XBeanBrokerFactory.createApplicationContext(String) line: 115	
      	XBeanBrokerFactory.createBroker(URI) line: 71	
      	BrokerFactory.createBroker(URI, boolean) line: 71	
      	BrokerFactory.createBroker(URI) line: 54	
      	StartCommand.startBroker(URI) line: 115	
      	StartCommand.runTask(List<String>) line: 74	
      	StartCommand(AbstractCommand).execute(List<String>) line: 57	
      	ShellCommand.runTask(List<String>) line: 143	
      	ShellCommand(AbstractCommand).execute(List<String>) line: 57	
      	ShellCommand.main(String[], InputStream, PrintStream) line: 85	
      	NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]	
      	NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39	
      	DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25	
      	Method.invoke(Object, Object...) line: 597	
      	Main.runTaskClass(List<String>) line: 251	
      	Main.main(String[]) line: 107	 

      During the runtime the client tries to add and remove connections; sometimes the removeConnection throws a NPE due to these transactions without ConnectionID.
      Take a look to the code fragment from TransactionBroker:

          public void removeConnection(ConnectionContext context, ConnectionInfo info, Throwable error) throws Exception {
              for (Iterator<Transaction> iter = context.getTransactions().values().iterator(); iter.hasNext();) {
                  try {
                      Transaction transaction = iter.next();
                  } catch (Exception e) {
                      LOG.warn("ERROR Rolling back disconnected client's transactions: ", e);
              synchronized (xaTransactions) {
                  // first find all txs that belongs to the connection
                  ArrayList<XATransaction> txs = new ArrayList<XATransaction>();
                  for (XATransaction tx : xaTransactions.values()) {
                      if (tx.getConnectionId().equals(info.getConnectionId()) && !tx.isPrepared()) {
                  // then remove them
                  // two steps needed to avoid ConcurrentModificationException, from removeTransaction()
                  for (XATransaction tx : txs) {
                      try {
                      } catch (Exception e) {
                          LOG.warn("ERROR Rolling back disconnected client's xa transactions: ", e);
              next.removeConnection(context, info, error);

      as you can see inside the loop there is a check for tx.getConnectionId().equals(info.getConnectionId()) that throws the NPE. When this occurs the connection isn't removed. This information isn't shared with the client that believes the opposite, so the next time that try to resend client information to server obtain (under jBoss) this error javax.transaction.xa.XAException: Broker: AMQ - Client: ID:srv001-47592-1336730655955-64:2 already connected from /
      that can be bound to the former server fails.
      This scenario can be found inside the attached logs.


        1. jBoss_server.log
          30 kB
          Antonio D'Errico
        2. ActiveMQ_server.log
          7 kB
          Antonio D'Errico



            • Assignee:
              gtully Gary Tully
              antonioderrico Antonio D'Errico
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              • Created: