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From Victor <dreamland_sk...@mail333.com>
Subject Re: [jira] Updated: (DIRMINA-762) WARN org.apache.mina.core.service.IoProcessor - Create a new selector. Selected is 0, delta = 0
Date Wed, 03 Feb 2010 09:02:10 GMT
[I tried to add this to Jira, but Jira throws me an error :) ]

Emmanuel, I remember a bug where ConcurrentLinkedQueue$Node was the main 
actor :) It is DIRMINA-709.

When I investigated it, I have seen that GC was busy all the time and 
there were tens of millions of ConcurrentLinkedQueue$Node objects, they 
were allocated and released frequently. I tried to profile our server 
with YourKit profiler... without success because of high load (it was in 
production).
Then I prepared my own "profiling tool" for this concrete problem. It 
uses AspectJ - I have added an aspect for Queue.offer() and 
Collection.add() method executions and grabbed most popular stack-traces 
from where these methods were called. If necessary, I can share my 
"tool" here.

Emmanuel Lecharny (JIRA) wrote:
>      [ https://issues.apache.org/jira/browse/DIRMINA-762?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
> 
> Emmanuel Lecharny updated DIRMINA-762:
> --------------------------------------
> 
>     Attachment: Screen shot 2010-02-02 at 7.49.18 PM.png
>                 Screen shot 2010-02-02 at 7.49.13 PM.png
> 
> Here are 5 snapshots :
> 3 for the server
> 2 for the client
> 
> They expose :
> - Memory + CPU over time
> - Threads at the end of the test (green = running)
> - and allocated objects on the server
> 
> One thing is strange : after having sent around 350 000 messages, the client and the
server suddenly slow down. CPU which topped at 85% on my system goes down to 30%, and this
is what we can see on both graphs.
> 
> Also we have an giant number of ConcurrentLinkedQueue$Node objects, which get garbage
collected later.
> 
> I guess that at some point, we are simply pushing too many messages in the queues.
> 
>> WARN org.apache.mina.core.service.IoProcessor  - Create a new selector. Selected
is 0, delta = 0
>> ------------------------------------------------------------------------------------------------
>>
>>                 Key: DIRMINA-762
>>                 URL: https://issues.apache.org/jira/browse/DIRMINA-762
>>             Project: MINA
>>          Issue Type: Bug
>>         Environment: Linux (2.6.26-2-amd64),  java version 1.6.0_12 and also 1.6.0_18.
>>            Reporter: Omry Yadan
>>            Priority: Critical
>>             Fix For: 2.0.0-RC2
>>
>>         Attachments: BufferCodec.java, Screen shot 2010-02-02 at 7.48.39 PM.png,
Screen shot 2010-02-02 at 7.48.46 PM.png, Screen shot 2010-02-02 at 7.48.59 PM.png, Screen
shot 2010-02-02 at 7.49.13 PM.png, Screen shot 2010-02-02 at 7.49.18 PM.png, Server.java,
StressClient.java
>>
>>
>> Mina server gets into a bad state where it constantly prints :
>> WARN org.apache.mina.core.service.IoProcessor  - Create a new selector. Selected
is 0, delta = 0
>> when this happens, server throughput drops significantly.
>> to reproduce run the attached server and client for a short while (30 seconds on
my box).
> 

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