Tomcat 4.1.18: 500+ Servlets locks up on Solaris under load

[Dov Rosenberg]

I have a Solaris server running Tomcat 4.1.18 and Java 1.3.0 with a 
single CPU and 2GIG RAM. The application has 500+ servlets that were 
originally developed under JDK 1.17b to run under the old Java Web 
Server on Windows NT4. The old system seems to handle the load much 
better than the new version. We have configured the Invoker to load the 
servlets automatically instead of explicitly naming them in the web.xml.

I am launching the Tomcat server with the following parameters:

	-server -Xms384m -Xmx384m -XX:NewSize=128m -XX:MaxNewSize=128m 
-Xconcurrentio -Xincgc -verbose:gc

under load the Tomcat server runs fine for a bit but once a servlet 
loads that retrieves a bunch of data, the CPU processing starts to 
increase until it pegs at 99% (according to TOP). All users then stop 
responding. The only way to recover is to terminate the process and 
restart Tomcat. The garbage collection indicates when the app becomes 
unresponsive the garbage collection shows a lot of full garbage 
collection cycles but the app never recovers - it essentially goes into 
an endless loop.

Some of the parameters in our server.xml are:

<Connector className="org.apache.coyote.tomcat4.CoyoteConnector" 
redirectPort="443" bufferSize="2048" port="8009" connectionTimeout="0" 
scheme="http" enableLookups="true" secure="false" 
protocolHandlerClassName="org.apache.jk.server.JkCoyoteHandler" 
debug="9" disableUploadTimeout="false" ProxyPort="0" maxProcessors="75" 
minProcessors="5" tcpNoDelay="true" acceptCount="10" 
useURIValidationHack="false">
      <Factory 
className="org.apache.catalina.net.DefaultServerSocketFactory"/>
    </Connector>

    <Connector className="org.apache.coyote.tomcat4.CoyoteConnector" 
redirectPort="-1" bufferSize="2048" port="80" connectionTimeout="0" 
scheme="http" enableLookups="true" secure="false" 
protocolHandlerClassName="org.apache.coyote.http11.Http11Protocol" 
debug="9" disable UploadTimeout="false" proxyPort="0" 
maxProcessors="-1" minProcessors="5" tcpNoDelay="true" acceptCount="10" 
useURIValidationHack="true">
	<Factory 
className="org.apache.catalina.net.DefaultServerSocketFactory"/>
    </Connector>

I am running Tomcat on port 80 as the root user if that has any bearing 
on things. Originally we had Apache in the mix, but to simplify 
figuring out the problems we have configured Tomcat to act as the web 
server for the time being. Some of the static resource directories are 
symbolic links.

Dov Rosenberg
Conviveon Corporation
407-339-1177 ext 102
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