Asynchronous Camel Component - doStop() called immediately

问题

I am trying to create a camel component which consumes an API from an external service.

My Route is as follows

from("myComponent:entity?from=&to=")
.to("seda:one")

from("seda:one")
.aggregate(constant(true), new GroupedBodyAggregationStrategy())
.completionSize(5)
.completionTimeout(5000)
.process( new Processor1() )
to("seda:two")

.
.
.


from("seda:five")
.to("myComponent2:entity")

I implemented my component consumer as follows

public class MyComponentConsumer extends DefaultConsumer {

    public MyComponentConsumer(MyComponentEndpoint endpoint, Processor processor) {
        super(endpoint, processor);
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();
        flag = true;
        while ( flag ) {
            //external API call
            Resource resource = getNextResource();
            if ( resource.next() == null ) {
                flag = false;
            }
            Exchange ex = endpoint.createExchange(ExchangePattern.InOnly);
            ex.getIn().setBody(resource.toString());
            getAsyncProcessor().process(
                            ex
                            doneSync -> {
                                LOG.info("Message processed");
                            }
                    );
        }
    }

    @Override
    protected void doStop() throws Exception {
        super.doStop();
        System.out.println("stop ---- ");
    }
}

Everything worked fine and the data was propogating through the route. My only problem was that data did not propogate to the next part until the whole of this process was completed. And the next parts were running asynchronously.

I looked at the example of StreamConsumer and tried to implement it to my code using a runnable and an executorService. But if I do that consumer stops as soon as it starts.

I changed the code to

public class MyComponentConsumer extends DefaultConsumer implements Runnable

and added

private ExecutorService executor;
getEndpoint().getCamelContext().getExecutorServiceManager().newSingleThreadExecutor(this, "myComponent");
executor.execute(this);

and moved my logic inside the run() method. But, the consumer thread ends as soon as it starts. and the async processor does not transfer the data properly.

Is there any other way to implement the functionality I need or am I mistaken somewhere here. Any help would be appreciated.

回答1:

What version of camel are you using?

There was an issue with managing the state of consumer in camel 2.x which was fixed in camel 3.x CAMEL-12765 which can lead to the issue you are describing here.

If you are on camel 2.x try using newScheduledThreadPool instead of newSingleThreadExecutor. Also executor.schedule(this, 5L, TimeUnit.SECONDS) instead of executor.execute(this).

Delayed start of executor might help avoid the problem you are facing.

来源：https://stackoverflow.com/questions/63858617/asynchronous-camel-component-dostop-called-immediately

标签

apache-camel

consumer

spring-camel