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From André Warnier ...@ice-sa.com>
Subject Re: AJP connection timeout setting/Tomcat 6 vs. 7 questions
Date Fri, 09 Dec 2011 09:37:48 GMT
Kari Scott wrote:
> 
> 
> 
> On Dec 6, 2011, at 2:25 PM, André Warnier wrote:
> 
>> Kari Scott wrote:
>>> We are running Tomcat 6. 0.32 with jdk1.6.0_26 on Solaris 10, mod_ajp 1.3  and
Apache 2.2.21 on all but one production server which is the same except for it's running Tomcat
7.0.21.
>>> I have some questions regarding connection timeout settings. Occasionally, when
the site is busier we see jumps in the number of connections to 8009 and then that number
stays high for about 30 minutes before settling back down into our average range. A thread
dump shows that these connections correspond to these socket threads:
>>> "TP-Processor222" daemon prio=3 tid=0x00c76400 nid=0x5669 runnable [0x8cf7f000]
>>>   java.lang.Thread.State: RUNNABLE
>>>        at java.net.SocketInputStream.socketRead0(Native Method)
>>>        at java.net.SocketInputStream.read(SocketInputStream.java:129)
>>>        at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>>>        at java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
>>>        at java.io.BufferedInputStream.read(BufferedInputStream.java:317)
>>>        - locked <0xcb2a0eb0> (a java.io.BufferedInputStream)
>>>        at org.apache.jk.common.ChannelSocket.read(ChannelSocket.java:628)
>>>        at org.apache.jk.common.ChannelSocket.receive(ChannelSocket.java:566)
>>>        at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:693)
>>>        at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:898)
>>>        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
>>>        at java.lang.Thread.run(Thread.java:662)
>>> The problem isn't so much that they stick around, but when these first start
increasing, there is a noticeable hit in performance and evidence that threads are waiting
for resources. Oddly, the one trial Tomcat 7 server with the same connector, load and code
never experiences this problem. We currently don't have a connectionTimeout specified for
our connector so my plan is to try the following:
>>>   <Connector port="8009" protocol="AJP/1.3" connectionTimeout="20000" redirectPort="8443"
/>
>>> Here are my questions:
>>> *Do I also need to set the connection_pool_timeout in the worker? Or is that
the one I should be changing instead of connectionTimeout?
>>> *Is there a different time out setting I should be looking at?
>>> *Is there an easy explanation as to why Tomcat 7 never experiences this issue?
I'm just wondering (o.k. hoping) that there is some magic Tomcat 7 default setting some place
that we can add to our Tomcat 6 environments that can help us out until we've upgraded everything.
>> Just a question, to add to your excellent summary above : in your front-end server
configuration, what are the settings related to keep-alive ?
>>
> 
> 
> All the servers have the following Apache settings: 
> 
> KeepAlive On
> MaxKeepAliveRequests 200
> KeepAliveTimeout 15
> 

So, what happens if you set

KeepAliveTimeout 3

?

> 
> 
>> And maybe, can you provide an example of the server.xml (comments and sensitive info
removed) for both a server which experiences the issue, and for the 7.0 server which doesn't
? (paste them inside the message, the list strips most attachments).
>>
> 
> 
> I sure can. I also removed some of the entries that were exactly the same so it's easier
to see the differences: 
> 
> *********************************************************************************
> Tomcat 7 server.xml:
> 
> <Server port="8005" shutdown="SHUTDOWN">
>   <Service name="Catalina">
>     <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
>     <Engine name="Catalina" defaultHost="localhost">
> 
>       <Host name="localhost"  appBase="webapps"
>             unpackWARs="false" autoDeploy="false">
> 
>         <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
>                prefix="localhost_access_log." suffix=".txt"
>                pattern="%h %l %u %t &quot;%r&quot; %s %b" resolveHosts="false"/>
> 
>       </Host>
>     </Engine>
>   </Service>
> </Server>
> 
> 
> Tomcat 6 server.xml:
> 
> <Server port="8005" shutdown="SHUTDOWN">
>   <Service name="Catalina">
>     <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
>     <Engine name="Catalina" defaultHost="localhost">
> 
>         <Valve className="com.jamonapi.http.JAMonTomcatValve"/>
> 
>       <Host name="localhost"  appBase="webapps"
>             unpackWARs="false" autoDeploy="false"
>             xmlValidation="false" xmlNamespaceAware="false">
>       </Host>
>     </Engine>
>   </Service>
> </Server>
> 
> *********************************************************************************
> 
> So the big difference is the presence of the JaMON Valve we're using on Tomcat 6 and
but accidentally forgot to put on Tomcat 7. Maybe this was a fortuitous mistake. I'll try
removing it from one of our Tomcat 6 servers to see if that's the culprit. We don't need that
access logging valve enabled on Tomcat 7 either, so this was a really good exercise to go
through. Thanks!
> 
> 
> 
> -kari
> 
> 
> 
> 
> _________________________________
> Kari Scott
> Senior Programmer
> kari.scott@cdw.com
> 
> CDW
> 5520 Research Park Drive
> Madison, WI 53711
> Office: 608 298 1223
> Fax: 608 288 3007
> 
> 
> 
> 
> 
> 
> 
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