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From "Geoff Cadien" <gcad...@gmail.com>
Subject Re: Why high CPU load?
Date Thu, 26 Jul 2007 04:25:58 GMT
On 7/25/07, McEase <mcease@gmail.com> wrote:
>
>
> Hi all,
>
> I have a server program based on mina which provides services to clients
> and
> also acts as a client of other servers. I found that when there're lots of
> client come and request a service and go (at a moment, there aren't so
> many
> clients), the CPU load of my program is very high. I profiled my program
> through java's agentlib hprof, like this:


First let me say that I'm new to MINA myself so take what I have to say with
a grain of salt.  A high cpu load isn't always a bad thing, especially since
you mention you see a high load with lots of clients.


$ java -agentlib:hprof=cpu=samples,depth=8 -cp $MyClassPath MyClass
>
> I got the following results:
>
> ......................
> TRACE 300291:
>         sun.nio.ch.PollArrayWrapper.poll0(PollArrayWrapper.java:Unknown
> line)
>         sun.nio.ch.PollArrayWrapper.poll(PollArrayWrapper.java:100)



What  JDK version/OS are you using?  I ask because at least on Linux, jdk
1.6 uses epoll and not poll.  A later update of jdk 1.5 can also use epoll
but you have to set the SelectorProvider using a System property.  If you
are using Linux epoll is much more efficient and might decrease your cpu
load.

-geoff

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