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From "Damien Delautre (JIRA)" <j...@apache.org>
Subject [jira] Created: (CAMEL-3348) DefaultShutdownStrategy and ShutdownAware losing exchange
Date Fri, 19 Nov 2010 22:03:26 GMT
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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