You could try using the Oracle utility - "jstat" - for analyzing the GC in an active Java process (PID) The "gcold" option helps us to peep into the Old Generation area jstat -gcold PID jstat -gcoldcapacity PID
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jstat.html -----Original Message----- From: Berneburg, Cris J. - US <cberneb...@caci.com.INVALID> Sent: Thursday, May 27, 2021 1:24 PM To: users@tomcat.apache.org Subject: [OT] web app big memory usage? Hi Folks :-) One of our web apps is using a "lot" of memory, specifically a big user query. We'd like to find out why. The Tomcat Web Application Manager Find leaks button said that "No web applications appear to have triggered a memory leak on stop, reload or undeploy." Tomcat Manager Server Status shows that 1.7GB (82%) of G1 Old Gen space is being used that has not been recycled yet. I grabbed a heap dump and used Eclipse Memory Analyzer, and it shows that only 94MB of memory is being used when G1 Old Gen space used 1.8GB. MAT seems to be looking only at the active objects, not the discarded ones. IOW, we're looking at what the app is doing ATM, not what it already did. I want to explore the 1.7GB garbage pile to see what's being thrown away, not what things are still being used, to determine wastefulness. 1. Is there a way to analyze uncollected garbage? 2. Is that a reasonable way to identify potential memory usage problems? Some technical specifics: * TC 8.5.63 * Java 1.8.0_291 * AWS EC2 instance. * Windows Server 2016. * Instance started as Windows Service. * There are other TC instances on the same server. * Each TC instance has multiple apps. Thanks for reading this far. :-) -- Cris Berneburg CACI Senior Software Engineer ________________________________ This electronic message contains information from CACI International Inc or subsidiary companies, which may be company sensitive, proprietary, privileged or otherwise protected from disclosure. The information is intended to be used solely by the recipient(s) named above. If you are not an intended recipient, be aware that any review, disclosure, copying, distribution or use of this transmission or its contents is prohibited. If you have received this transmission in error, please notify the sender immediately. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
