Hi,
>> I modified the proposed patch and attached it.
>>
>> As Alexey's words, I think that it is impossible that we support
>> round robin SelectionKey distribution for UDP server-side.
>>
>> So I support UDP client-side connections distribution in the
>> attached patch instead of server-side.
>>
>> In UDPConnectorHandler#connect(), I select a
>> relativeSelectorHandler from aux controller. Then, client-side's
>> OP_READ will be controlled in aux controller.
>>
>> When I used many UDPConnectorHandlers concurrently on 4 CPUs(local
>> Windows machine), I found that the perf was improved. (About
>> 30%~40%??, but it is not accurate)
>>
>> Could you please review this?
>
>
> It seems to me that RoundRobinSelectorHandler does not distribute
> the load
> in a round robin manner. That is because roundRobinCounter is a
> primitive
> integer, so it seems that nextController method returns same
> ReadController to different threads.
>
> I am not sure about this, but should we change roundRobinCounter to
> volatile int, or AtomicInteger? This is not a big issue, though.
Good catch!
Though this issue could occur only, if we have more than 1 transport
(SelectorHandler) per Controller, because otherwise only one
SelectorRunner calls RRSelectorHandler, IMHO it makes sense to make
counter atomic.
Thank you.
WBR,
Alexey.
>
>
> Minoru
>
>> And if you find some points which I have missed, please let me know.
>>
>> Thanks!
>>
>> --
>> Bongjae Chang
>>
>>
>> ----- Original Message -----
>> From: Bongjae Chang
>> To: dev_at_grizzly.dev.java.net
>> Sent: Monday, June 29, 2009 9:26 PM
>> Subject: Re: Supporing OP_READ round robin on UDP
>>
>>
>> Hi Alexey,
>>
>> I see. You are right!
>>
>> I was perhaps misunderstanding the issue. :(
>>
>> I will investigate it again.
>>
>> Thank you for your advice.
>>
>> --
>> Bongjae Chang
>>
>>
>> ----- Original Message -----
>> From: Oleksiy Stashok
>> To: dev_at_grizzly.dev.java.net
>> Sent: Monday, June 29, 2009 8:23 PM
>> Subject: Re: Supporing OP_READ round robin on UDP
>>
>>
>> Hi Bongjae,
>>
>>
>> can you pls. describe the usecase, how we can support round
>> robin SelectionKey distribution for UDP server-side? We usually
>> open just one UDP server-side listener on specific port, which is
>> represented by single DatagramChannel. So *all* the UDP client-side
>> requests come just to *single* server-side DatagramChannel, so I'm
>> not sure how we're able to distribute something here...
>> On other side, it could be good idea to support UDP client-side
>> connections distribution, when we use UDPConnectorHandlers.
>>
>>
>> Thanks.
>>
>>
>> WBR,
>> Alexey.
>>
>>
>> On Jun 27, 2009, at 7:39 , Bongjae Chang wrote:
>>
>>
>> Hi,
>>
>> I am investigating Grizzly issue #600( https://grizzly.dev.java.net/issues/show_bug.cgi?id=600
>> , "OP_READ round robin in selector" ).
>>
>> And I attached the proposed patch.
>>
>> I tested all unit tests locally on 4 CPUs.
>>
>> But I couldn't do a performance test completely, so I think
>> that more performance tests should be done.
>>
>> When I was going on the issue, I had a question.
>>
>> UDP is different from TCP because OP_READ is available without
>> OP_ACCEPT in server side.
>>
>> When TCP receives OP_ACCEPT in main selector thread, TCP
>> delivers OP_READ to auxiliary ReadController.
>>
>> It's OK.
>>
>> In my patch about UDP,
>>
>> I ignored a first OP_READ which was received in main selector
>> thread for dispatching it, and registered it in auxiliary
>> ReadController again like TCP.
>>
>> In other words, whenever UDP receives OP_READ directly in main
>> selector thread, thread's context switch will occur for supporting
>> round robin.
>>
>> But, if round robin on UDP is not supported, first OP_READ is
>> handled in main selector thread without thread's context switch
>> directly because of leader flollower strategy.
>>
>> So it is questionable whether UDP's round robin will improve
>> the performance or not. But I believe that it will be able to
>> improve the performance in some circumstances.
>>
>> If you have better idea for supporing round robin on UDP,
>> please advice me.
>>
>> And please review the attached patch again.
>>
>> Thanks!
>>
>> --
>> Bongjae Chang<patch.txt>
>>
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