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  1. Camel
  2. CAMEL-3348

DefaultShutdownStrategy and ShutdownAware (SedaConsumer) losing exchange

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.5.0
    • Fix Version/s: 2.6.0
    • Component/s: camel-core
    • Labels:
      None

      Description

      There's a problem when we shutdown the camel context with a seda endpoint.

      In the SedaConsumer, the exchange is removed from the queue and then, later, is added to the InflightRepository as shown in the following code (I put comments where it is done):

      public void run() {
              BlockingQueue<Exchange> queue = endpoint.getQueue();
              while (queue != null && isRunAllowed()) {
                  final Exchange exchange;
                  try {
                      exchange = queue.poll(1000, TimeUnit.MILLISECONDS); // The exchange is removed here from the queue
                  } catch (InterruptedException e) {
                      if (LOG.isDebugEnabled()) {
                          LOG.debug("Sleep interrupted, are we stopping? " + (isStopping() || isStopped()));
                      }
                      continue;
                  }
                  if (exchange != null) {
                      if (isRunAllowed()) {
                          try {
                              sendToConsumers(exchange); // Call to sendToConsumers detailed below
      
                              if (exchange.getException() != null) {
                                  getExceptionHandler().handleException("Error processing exchange", exchange, exchange.getException());
                              }
                          } catch (Exception e) {
                              getExceptionHandler().handleException("Error processing exchange", exchange, e);
                          }
                      } else {
                          if (LOG.isWarnEnabled()) {
                              LOG.warn("This consumer is stopped during polling an exchange, so putting it back on the seda queue: " + exchange);
                          }
                          try {
                              queue.put(exchange);
                          } catch (InterruptedException e) {
                              if (LOG.isDebugEnabled()) {
                                  LOG.debug("Sleep interrupted, are we stopping? " + (isStopping() || isStopped()));
                              }
                              continue;
                          }
                      }
                  }
              }
          }
      
          protected void sendToConsumers(Exchange exchange) throws Exception {
              int size = endpoint.getConsumers().size();
      
              if (size > 1) {
      
                  if (LOG.isDebugEnabled()) {
                      LOG.debug("Multicasting to " + endpoint.getConsumers().size() + " consumers for Exchange: " + exchange);
                  }
                 
                  MulticastProcessor mp = endpoint.getConumserMulticastProcessor();
      
                  AsyncProcessorHelper.process(mp, exchange, new AsyncCallback() {
                      public void done(boolean doneSync) {
                      }
                  });
              } else {
                  AsyncProcessorHelper.process(processor, exchange, new AsyncCallback() { // This line will create the UnitOfWork (in UnitOfWorkProcessor) which will put the exchange in the InflightRepository
                      public void done(boolean doneSync) {
      
                      }
                  });
              }
          }
      

      If the shutdown occurs between these two actions, the DefaultShutdownStrategy will shutdown the route even if there is a message in progress. And the message will be lost.

      Here is the code of ShutdownTask in DefaultShutdownStrategy which cause the shutdown even if there is some messages still in progress. (I put comments in it to show the state of the seda queue and InflightRepository if it is called between the queue.poll() and the InflightRepository.add())

      for (Consumer consumer : order.getInputs()) {
                              int inflight = context.getInflightRepository().size(consumer.getEndpoint()); // check the number of inflight exchanges which is 0 because the UnitOfWork is not created
      
                              if (consumer instanceof ShutdownAware) {
                                  inflight += ((ShutdownAware) consumer).getPendingExchangesSize(); // check the number of exchange in the seda queue which is 0 because the message is already removed
                              }
                              if (inflight > 0) {
                                  size += inflight;
                                  if (LOG.isDebugEnabled()) {
                                      LOG.debug(inflight + " inflight and pending exchanges for consumer: " + consumer);
                                  }
                              }
                          }
      

      You can reproduce it by putting a breakpoint in the method

      protected void sendToConsumers(Exchange exchange)

      in SedaConsumer and calling stop() on the CamelContext while the thread is suspended by the breakpoint.

      We caught the problem in a unit test where we were testing the shutdown and when our test server was under heavy load.

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            • Assignee:
              davsclaus Claus Ibsen
              Reporter:
              ddelautre Damien Delautre
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              • Created:
                Updated:
                Resolved: