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From Tobias Bieniek <Tobias.Bien...@gmx.de>
Subject Re: High server load due to SessionOutputBufferImpl.flush()
Date Sun, 14 Sep 2014 19:49:18 GMT
Hi Oleg,

I had to modify the logging code a bit to work with the v4.3 branch
and I've also changed the loggers to use our slf4j logging, but on
friday we've finally deployed the code to one of our server and waited
for the spinning to appear again. This is what I see a lot in the
logs:

2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 31]
NHttpServerConnection:144 - produceOutput : http-incoming-22190:
Produce output
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 183]
NHttpServerConnection:144 - produceOutput : http-incoming-13597:
Produce output
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 31]
NHttpServerConnection:112 - close : http-incoming-22190: Close
connection
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 183]
NHttpServerConnection:112 - close : http-incoming-13597: Close
connection
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 31]
NHttpServerConnection:144 - produceOutput : http-incoming-22190:
Produce output
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 183]
NHttpServerConnection:144 - produceOutput : http-incoming-13597:
Produce output
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 31]
NHttpServerConnection:112 - close : http-incoming-22190: Close
connection
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 183]
NHttpServerConnection:112 - close : http-incoming-13597: Close
connection
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 31]
NHttpServerConnection:144 - produceOutput : http-incoming-22190:
Produce output
2014-09-14 19:40:17,630 DEBUG [I/O dispatcher 183]
NHttpServerConnection:144 - produceOutput : http-incoming-13597:
Produce output
2014-09-14 19:40:17,631 DEBUG [I/O dispatcher 31]
NHttpServerConnection:112 - close : http-incoming-22190: Close
connection
2014-09-14 19:40:17,631 DEBUG [I/O dispatcher 183]
NHttpServerConnection:112 - close : http-incoming-13597: Close
connection

I'm not exactly sure what the problem is here, but it looks wrong to
me. I hope someone here is able to explain what might be happening
there.

Would you want me to share the modified logging code so you could
integrate it into your repo again?

Tobias



2014-09-10 14:58 GMT+02:00 Oleg Kalnichevski <olegk@apache.org>:
> 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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