My AEM server after a few days, becomes unresponsive and crashes. As per this article - https://helpx.adobe.com/experience-manager/kb/check-and-analyze-if-JCR-session-leaks-in-your-AEM-instance.html, on checking http://localhost:4502/system/console/jmx I found out that there are more than 60,000 SessionStatistics objects. I would like to know what these represent? Are these active sessions? or is this the list of all the sessions ever created on AEM server?
I would like to know what these represent? Are these active sessions? or is this the list of all the sessions ever created on AEM server?
Yes, these are active open sessions running currently on your AEM server - created since you last started your instance. You can find the last started time from /system/console/vmstat and all the session objects will have a timestamp after the Last Started time. You'll notice the timestamp against the session name. Something similar to this.
"communities-user-admin@session-1132@25/10/2018 5:03:26 PM"
The link you've posted already indicates potential fixes for open sessions.
Another possible reason for Build up of session objects is due to inefficient long running JCR queries (queries without indexes, very broad predicates, etc). This could lead to increase in garbage collection because of increase in memory usage (if mem params are not specified in start script), analysing gc.log might provide some insights. If you know pretty well that queries are causing build up of session objects, you can use these params in your start script to optimize the resources being used.
-Doak.queryLimitInMemory=1000 -Doak.queryLimitReads=1000 -Dupdate.limit=1000 -Doak.fastQuerySize=true
To find location of gc.log, use lsof
lsof -p ${JAVA PID} | grep gc.log