Performance issues (high CPU)

Issues and Questions related to running Apache Tomcat on z/OS
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tracy.ison@relx.com
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Joined: Thu Dec 07, 2017 8:45 am

Performance issues (high CPU)

Post by tracy.ison@relx.com » Wed Feb 06, 2019 9:58 am

We are migrating a z/OS application from running in a WebSphere container to running in Tomcat. When running the Tomcat version the Tomcat started task consumes excessive CPU. The same behavior is not observed in the WebSphere version. Are there specific JZOS / JVM / Tomcat configuration options we should consider to achieve similar performance. Can we tune the JZOS Tomcat instance to limit the CPU utilization? Limit threads? Limit forked processes?

Thank you,
Tracy

dovetail
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Re: Performance issues (high CPU)

Post by dovetail » Wed Feb 06, 2019 11:48 am

Are you running with the same JVM version and JVM options in Websphere container JVM that you are running in Tomcat?
That is where I would start.

tracy.ison@relx.com
Posts: 3
Joined: Thu Dec 07, 2017 8:45 am

Re: Performance issues (high CPU)

Post by tracy.ison@relx.com » Wed Feb 06, 2019 5:43 pm

Thank you for your reply. We are upgrading our java version to java 8 as well as migrating to Tomcat. We have reviewed JVM settings and have not yet found any differences that would lead us to suspect that this is the cause of the excessive CPU utilization. We are continuing to investigate. We did find that Xshareclasses is specified for WebSphere and not for Tomcat. I would expect this to improve long run / overall performance versus impacting the behavior we are observing which is a dramatic increase in CPU utilization when specific test cases are executed against the Tomcat versus the WebSphere version of the deployment. Appreciate any further tips you might share.

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