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Date: Fri, 19 Nov 2010 17:03:26 -0500 (EST)
From: "Damien Delautre (JIRA)" <jira@apache.org>
To: camel-dev@activemq.apache.org
Subject: [jira] Created: (CAMEL-3348) DefaultShutdownStrategy and
 ShutdownAware losing exchange
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DefaultShutdownStrategy and ShutdownAware losing exchange
---------------------------------------------------------

                 Key: CAMEL-3348
                 URL: https://issues.apache.org/activemq/browse/CAMEL-3348
             Project: Apache Camel
          Issue Type: Bug
          Components: camel-core
    Affects Versions: 2.5.0
            Reporter: Damien Delautre


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):

{code}
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) {

                }
            });
        }
    }
{code}

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())

{code}
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);
                            }
                        }
                    }
{code}
You can reproduce it by putting a breakpoint in the method {code}protected void sendToConsumers(Exchange exchange){code} 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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