Hi Bill,
On 07/11/12 20:09, Bill Burke wrote:
>
>
> On 11/7/2012 2:36 PM, Marek Potociar wrote:
>>
>> On Nov 7, 2012, at 8:14 PM, Jan Algermissen <jan.algermissen_at_nordsc.com
>> <mailto:jan.algermissen_at_nordsc.com>> wrote:
>>
>>>
>>> On Nov 7, 2012, at 7:59 PM, Bill Burke <bburke_at_redhat.com
>>> <mailto:bburke_at_redhat.com>> wrote:
>>>
>>>>
>>>>
>>>> On 11/7/2012 11:50 AM, Jan Algermissen wrote:
>>>>> Hi,
>>>>>
>>>>> do you have an estimate what the overhead of using an AsyncResponse
>>>>> is, if you send back a sync. response for the majority of cases?
>>>>>
>>>>> Use Case:
>>>>>
>>>>> Implement a resource method that retains the opportunity for
>>>>> handling a request asynchronously but decides thatonly when the
>>>>> method is actually invoked. IOW, when the method determines that a
>>>>> synchronous response is fine, it simply invokes the async response
>>>>> right away.
>>>>>
>>>>> Does that significanly affect performance or resource usage?
>>>>
>>>> I don't know. I could do a mini bench vs. JBoss Web Servlet
>>>> container, but I"m too lazy.
>>>>
>>>> BTW, I have a similar use case that I've discussed before:
>>>>
>>>> @POST
>>>> void post(@Suspended AsyncResponse res) {
>>>>
>>>> res.resume(Response.status(202).build()); // 202, Accepted
>>>>
>>>> // do an expensive op.
>>>>
>>>> }
>>>>
>>>> In this case, the client gets a response immediately, while the
>>>> server does something in the background. Really simple, no need for
>>>> queues, threads, etc.
>>>
>>> Well, yes that is how you do async properly with HTTP :-)
>>
>> No, it is not. Assuming the the code above runs in the same container
>> thread that is dedicated to processing incoming requests, in the code
>> above you return the response to the client quickly, but you will still
>> continue to occupy the request processing container thread for your
>> long-runnning operation effectively cancelling out any positive effect
>> of the async operation on the server-side.
>>
>> To do it right, you would have to do this instead:
>>
>
> To paint this as a fact is misleading. You have your own opinion here
> that is definitely not shared by myself.
>
I was planning to ask earlier, but I wonder how do you make it work,
a code like this
>>>> @POST
>>>> void post(@Suspended AsyncResponse res) {
>>>>
>>>> res.resume(Response.status(202).build()); // 202, Accepted
>>>>
>>>> // do an expensive op.
>>>>
>>>> }
without blocking the thread which called post() ? Do you use some JBoss
magic that releases the current thread in
res.resume(Response.status(202).build());
and then replaces it with some internal thread for the flow to continue ?
Cheers, Sergey