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
> 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 "%r" %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.sc...@cdw.com
CDW
5520 Research Park Drive
Madison, WI 53711
Office: 608 298 1223
Fax: 608 288 3007
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