Hi Mircea, the heap may not get smaller but data inside the old heap may be collected and memory freed, depending what gc algorithm you use in your application. Old gen space could be collected even without full gc running.
It will be better to publish the gc log or show information of the analysis using the gceasy or any other tool to analyze gc logs. List of some tools is here https://fasterj.com/tools/gcloganalysers.shtml I use the GCView to analyze the gc logs locally or sometimes the gceasy already mentioned. This gives us a better view of your problem. Regards, Zdenek Henek On Tue, Jul 29, 2025 at 7:33 PM Mircea Butmalai <mircea.butma...@radcom.ro> wrote: > Hi, > > > I have created a public repo on github with the following URL: > mirceabutmalai/test-docs: test-docs< > https://github.com/mirceabutmalai/test-docs> > > Inside you have 2 png files which are referred from initial email and also > the complete jstat log file obtained during test. > > > Thanks, > Mircea > > > [ > https://opengraph.githubassets.com/43dcdbbd03743ae80e9e59a991bf12d1e067febe29ff532cf4b95c7c744c460d/mirceabutmalai/test-docs > ]<https://github.com/mirceabutmalai/test-docs> > GitHub - mirceabutmalai/test-docs: test-docs< > https://github.com/mirceabutmalai/test-docs> > test-docs. Contribute to mirceabutmalai/test-docs development by creating > an account on GitHub. > github.com > > [ > https://opengraph.githubassets.com/43dcdbbd03743ae80e9e59a991bf12d1e067febe29ff532cf4b95c7c744c460d/mirceabutmalai/test-docs > ]<https://github.com/mirceabutmalai/test-docs> > GitHub - mirceabutmalai/test-docs: test-docs< > https://github.com/mirceabutmalai/test-docs> > test-docs. Contribute to mirceabutmalai/test-docs development by creating > an account on GitHub. > github.com > > ________________________________ > From: Gregg, John E. <john.e.gr...@wellsfargo.com.INVALID> > Sent: Tuesday, July 29, 2025 9:09 PM > To: Tomcat Users List <users@tomcat.apache.org> > Subject: RE: memory leak analysis > > Mircea, > > If your employer allows it, upload your GC logs to > https://gceasy.io/gc-index.jsp. One benefit of this tool over some of > the others is that it actually gives you qualitative feedback on what might > be wrong, if anything. > > Thanks > > > > From: Mircea Butmalai <mircea.butma...@radcom.ro> > Sent: Tuesday, July 29, 2025 8:21 AM > To: Tomcat Users List <users@tomcat.apache.org> > Subject: memory leak analysis > > > > Hello, > > I have analyzed java memory heap for approximately default tomcat 10.1.43 > installation. > Approximately default tomcat 10.1.43 installation means: > > * Installation of tomcat is done on CentOS 9 with uname output as: > Linux centos9dev1.local 5.14.0-533.el9.x86_64 #1 SMP PREEMPT_DYNAMIC Fri > Nov 22 15:05:06 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux > > > * Java environment is Eclipse Temurin JDK 21.0.7 > > * Apache Tomcat 10.1.43 archive tar.gz obtained from official tomcat > site and installed under special folder inside /opt specific to our project > > * No .bat files in tomcat bin folder > > * no examples and docs webapps, only default ROOT, manager and > host-manager webapps are delivered from official tomcat archive. No other > custom webapps are present in this heap memory test. > > * tomcat file conf/tomcat-users.xml contains user with roles > manager-script, manager-status, manager-jmx, manager-gui > > * Custom startup / shutdown / check bash scripts that basically launch > catalina.sh with custom java options. > > * The check script verifies tomcat process and if ok it checks > using manager URL /manager/text/serverinfo in order to decide if tomcat is > ok. The client http access is done using system application curl. > > * These custom scripts launch process under custom created system user > and all tomcat and java files are owned by this custom system user > > The heap memory analysis was done as follows: > > * Due to the fact that server info manager URL is already accessed by > our custom check script at a rate of 0.1 requests per second it was decided > that first test was to inject a bigger rate (5 requests per second) into > tomcat server from this manager URL /manager/text/serverinfo. Only this > requests where inside tomcat. > > * Before injecting these requests a jstat process was started in order > to monitor heap memory at a rate of 5s. So we have a text file output from > this java application that offers stats about java memory collections. > > * Data was collected for a duration of 265k seconds = aprox. 3 days > > Graphical representation of EU (eden space utilization in KB), OU (old > space utilization KB) and MU (metaspace utilization KB) are attached inside > this email. > > The questions are: > > 1. Why we have a constant increase for OU during this test. > > 1. The slope is significant and should be zero during this kind of test > at least after some reasonable time period like some minutes. > > 1. It is there a problem? When the slope is going to change to zero? > > 1. It seems like there is a very little slope even for MU which > increases from 16793.6 KB at 39k seconds to 16809 KB at 265k seconds. (diff > is 15.4 KB). The increase here is linearly distributed over the time > interval. It is a problem even here? > > Thanks, > Mircea Butmalai > >
