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From Oleg Kalnichevski <ol...@apache.org>
Subject Re: High server load due to SessionOutputBufferImpl.flush()
Date Wed, 10 Sep 2014 12:58:58 GMT
On Wed, 2014-09-10 at 13:59 +0200, Tobias Bieniek wrote:
> Hi guys,
> 
> we are running httpcore-nio on several production servers as an API
> frontend. Lately we upgraded httpcore from v4.2 to v4.3.2 and since
> then we are experiencing a much higher CPU load (constantly around
> 40%) and memory usage.
> 
> We have activated JMX on the servers, had a look with VisualVM and
> noticed that the Sampler shows SessionOutputBufferImpl.flush() to
> consume over 90% of the CPU time. So far we haven't been able to track
> why it is spending so much time flushing when the HTTP request load is
> actually rather low.
> 
> The memory graph in VisualVM shows that a lot of memory is allocated
> in what we suspect to be an endless loop somewhere, which would also
> explain the high CPU load.
> 
> As I said above we haven't been successful in debugging this problem
> and we would be very thankful for any ideas on how we could solve
> this.
> 
> Tobias Bieniek
> 

Hi Tobias

If any of the sessions is 'spinning' it should be fairly easy to find
out by using I/O session logging.

Can you add those (or similar) classes to your test project [1] and
reproduce the problem with I/O session logging turned on?

Oleg

[1]
http://svn.apache.org/repos/asf/httpcomponents/contrib/httpcore/trunk/src/main/java/org/apache/http/contrib/logging/



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