tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From yann grostete <yann.grost...@alcatel-lucent.fr>
Subject Re: CPU usage with APR and connectionTimeout impact
Date Thu, 02 Apr 2009 12:58:30 GMT
Hello,

The parameters connectionTimeout and keepAliveTimeout are not on the APR 
side. They are attributes of AJP and HTTP connectors.
Setting the value to 0 means no timeout (according to some mail exchange 
I found in tomcat mailing list).
No timeout is default value of this attribute.

My question is also: why a connector attribute has a so subtential 
impact on tomcat cpu usage, when APR is used?

And for the peers going to lunch after the initial connection, it's 
true: we have a large number of such peers.

Thank you for your help. And the help of "one of the veterans" will be 
very appreciated.
Regards

Taylan Develioglu a écrit :
> Funny,
>
> according to the documentation there exists no connectionTimeout
> attribute for the apr connector.
>
> Setting the value to '0' could mean all sorts of behavior, no way to
> know for sure short of  checking the code. (it could mean the connector
> will not wait for the uri line at all)
>
> I  can't comment about a correct value for your application.
>
> Setting it to a low value will  have the connector thread return to the
> pool faster on connections where the peer has gone to lunch after the
> initial connection. This only matters if you have a large number of such
> peers.
>
> I'm sure one of the veterans here can clear this up for you.
>   
>> Hello,
>>
>> In my project, we are using Tomcat 6.0.18, with APR 1.2.12 and tc
>> native 1.1.14 on an Redhat OS (Linux kernel 2.6.18).
>> There is a behavior that I can't explain:
>>
>> -with connectionTimeout="0", the process tomcat uses a huge percentage
>> of CPU, even if there is no traffic.
>> but we doesn't observe any problem and the response time is good.
>>
>> -with connectionTimeout="5000", the process tomcat uses a normal
>> percentage of CPU, when there is no traffic.
>>
>> -without APR and with connectionTimeout="0", the process tomcat uses a
>> normal percentage of CPU when there is no traffic.
>>
>> After different searches on the web, tomcat manual and mailing lists, I
>> don't find the reason of the link between CPU usage and
>> connectionTimeout/keepAliveTimeout with APR.
>> With the previous release of Tomcat (5.5) and APR, we have a similar CPU
>> usage (without traffic, high CPU load) and when we modify another
>> parameter ("firstReadTimeout"), the behavior also changes in the same
>> way.
>>
>> I know there is no real trouble, but I'm curious and prudent: I don't
>> like to do something, when I don't understand what is hidden behind.
>> Could somebody explain to me why Tomcat/APR has these behaviors?
>> Is there a performance risk to set connectionTimeout to 5000?
>>
>> Thank you for your answers.
>> Yann
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>> For additional commands, e-mail: users-help@tomcat.apache.org
>>
>>     
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
>   

---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org


Mime
View raw message