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From Todd Lipcon <t...@cloudera.com>
Subject Re: Hadoop RPC call response post processing
Date Tue, 28 Dec 2010 04:21:50 GMT
Hi Stefan,

Sounds interesting.

Maybe you're looking for o.a.h.ipc.Server$Responder?

-Todd

On Mon, Dec 27, 2010 at 8:07 PM, Stefan Groschupf <sg@101tec.com> wrote:

> Hi All,
> I'm browsing the RPC code since quite a while now trying to find any entry
> point / interceptor slot that allows me to handle a RPC call response
> writable after it was send over the wire.
> Does anybody has an idea how break into the RPC code from outside. All the
> interesting methods are private. :(
>
> Background:
> Heavy use of the RPC allocates hugh amount of Writable objects. We saw in
> multiple systems  that the garbage collect can get so busy that the jvm
> almost freezes for seconds. Things like zookeeper sessions time out in that
> cases.
> My idea is to create an object pool for writables. Borrowing an object from
> the pool is simple since this happen in our custom code, though we do know
> when the writable return was send over the wire and can be returned into the
> pool.
> A dirty hack would be to overwrite the write(out) method in the writable,
> assuming that is the last thing done with the writable, though turns out
> that this method is called in other cases too, e.g. to measure throughput.
>
> Any ideas?
>
> Thanks,
> Stefan




-- 
Todd Lipcon
Software Engineer, Cloudera

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