Are you sure you want preserved order on the sender side?
In essence to do that you may have to use a thread pool of 1, so the
tasks are processed in sequence.
I would assume the JDK in fact does grab the taks by order by default
as the thread pool executor uses a queue for the tasks (FIFO).
On the other hand if you want to process the responses in the same
order as the tasks was submitted, then you can use a CompletionService
for that.
There is no out of the box in the JDK, so we created one in Camel as
we needed it. See the org.apache.camel.util.concurrent package.
On Wed, Jun 1, 2011 at 7:04 AM, Jim Newsham <jnews...@referentia.com> wrote:
>
> Is it possible to send asynchronously while preserving order? For example:
>
> for (int i = 0; i <= COUNT; i++) {
> Object body = Integer.valueOf(i);
> producerTemplate.asyncCallbackRequestBody(URL, body, callback);
> }
>
> Assuming that "URL" is a FIFO queue, is there some way for the recipient to
> receive the messages in the order that the sender has sent them? I think
> the answer is no, since async calls just schedule a task on an executor, and
> it's possible for the thread scheduler to choose/process send tasks out of
> order. [*]
>
> If that's correct, then *if order is important*, all sends must be
> synchronous, and performance will suffer (transmission will be in serial
> instead of in parallel, and any network latency will make matters worse
> since InOut requires round-trip communication). For this case, it really
> would be useful to be able to async send and guarantee transmission order
> (for JMS or whatever endpoint being used).
>
> [*] One could set a single-threaded executor on the producer template. The
> call would be asynchronous and transmission in order, however the actual
> send operations would still be in serial (each InOut message must be
> completely processed before the next message is sent), so the performance
> would still suffer.
>
> Comments?
> Jim
>
>
>
>
--
Claus Ibsen
-----------------
FuseSource
Email: cib...@fusesource.com
Web: http://fusesource.com
Twitter: davsclaus, fusenews
Blog: http://davsclaus.blogspot.com/
Author of Camel in Action: http://www.manning.com/ibsen/
