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From Claus Ibsen <>
Subject Re: Asynchronous Routing Engine - Status
Date Fri, 02 Jul 2010 13:47:29 GMT
On Fri, Jul 2, 2010 at 3:33 PM, Claus Ibsen <> wrote:
> Hi
> Just to update the status that today I have implemented
> a) error handler will now schedule delayed redeliveries by default
> which thus allows to not block while the delay occurs. You can disable
> this behavior using the syncDelayed() option on the error handler /
> onException / routePolicy. And if you use transactions it will use
> synced delays to ensure the exchange will use the same thread again as
> the Transaction Manager requires to execute in the same thread
> context.

Just a though.

Do anyone think it would be best to keep the old behavior as default?
To block while delaying when routing synchronous?

For a single consumer thread this could cause it to be able to pickup
new messages which might also fail
and thus stack up messages on the delayed redelivery task queue?

I think I will flip back the default so it works as it have always
done, then people can turn this option on to have async delayed if
they want.

> b) delay and throttle EIP now have an option asyncDelayed() you can
> use to enable them to use non blocking delay as well
> The only question though would be if we should have an option to allow
> you to cancel tasks on shutdown. If you have messages queued up in the
> delay/throttle. Then a fast stop to cancel the pending tasks is
> possible. However the JDK ExecutorService API is damn poor in terms of
> stopping the thread pool. You can only shut it down which then cant
> restart it. And getting the pending tasks is also not possible unless
> you gather the Future references and then remember to keep this list
> up to date removing the done tasks.
> On Thu, Jul 1, 2010 at 1:58 PM, Claus Ibsen <> wrote:
>> Hi
>> The major goal for Camel 2.4 is introducing back the asynchronous
>> routing engine from the Camel 1.x days.
>> What we had replaced it with, just didn't cut it for the long run, so
>> we had to toss it out and replace it back with the 1.x variation.
>> However the 1.x variation is much more invasive in the camel core.
>> However the benefits are worth it.
>> There is a JIRA ticket to track this
>> We got so far with the code that we can move ahead the release
>> schedule for 2.4 and thus why Hadrian send out
>> an announcement yesterday.
>> The engine has been integrated with Apache ServiceMix JBI and NMR,
>> which means that in SMX 4.3 and Came. 2.4 onwards
>> you have much better scalability and utilization of the resources.
>> There is present only a single Camel component which leverages the
>> async routing as well which is Jetty.
>> The consumer side uses Jetty continuations and the producer side the
>> Jetty http async client.
>> We plan to expand this to other Camel components where async
>> communication is native supported by the component.
>> Such as Netty, Mina 2 (when its out), CXF producer, REST stuff and what else.
>> Mind that async routing does not work to the fullest if you are not
>> using transactions. Spring TM requires the transactional resources to
>> be
>> executed from the same thread context, which is why Camel will
>> fallback to route fully synchronous if you use transacted routes.
>> This works automatic and you dont have to worry about it to configure
>> any of the Camel endpoints to cater for this. It's just that Camel
>> will have the caller thread blocked while waiting for the async reply,
>> in case you for example to request/reply over NMR in a transaction.
>> Almost all the EIP patterns in Camel have been refactored to support
>> async routing engine as well. So you can use Splitter, Recipient List,
>> WireTap
>> and all the others in the most optimal way. Currently there are 3
>> outstanding works to be looked at:
>> - Throttler and Delayer EIP to not block while waiting
>> - Multicast, Recipient List and Splitter EIP to support async routing
>> engine when parallelProcessing option is enabled (this is a bit tricky
>> to do).
>> - RedeliverErrorHandler to use non blocking while waiting for delivery
>> (current only enabled if async routing has been kicked in) but we can
>> do this in a general.
>> --
>> Claus Ibsen
>> Apache Camel Committer
>> Author of Camel in Action:
>> Open Source Integration:
>> Blog:
>> Twitter:
> --
> Claus Ibsen
> Apache Camel Committer
> Author of Camel in Action:
> Open Source Integration:
> Blog:
> Twitter:

Claus Ibsen
Apache Camel Committer

Author of Camel in Action:
Open Source Integration:

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