Although the tuning parameters give you a good start to tuning your JVM, you must monitor GC performance to ensure you have the best settings to meet your needs. There are several tools to help you monitor Oracle JVM performance including.
Visual VM
This tool provides a centralized console for viewing Oracle JVM performance information, including garbage collector activities.
JMX Console
This tool helps display various statistics like Liferay DXP’s distributed cache performance, the performance of application server threads, JDBC connection pool usage, and more.
To enable JMX connections, add these JVM arguments:
-Dcom.sun.management.jmxremote=true
-Dcom.sun.management.jmxremote.port=5000
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false
If you’re running JMX Console from a another machine, add these JVM arguments too:
-Dcom.sun.management.jmxremote.local.only=false
-Dcom.sun.management.jmxremote.rmi.port=5000
-Djava.rmi.server.hostname=[place IP address here]
Garbage Collector Verbose Logging
Add the following configuration to your JVM arguments to activate verbose logging for the JVM garbage collector.
-verbose:gc -Xloggc:/tmp/liferaygc1.log -XX:+PrintGCDetails
-XX:+PrintGCCause -XX:+PrintGCApplicationConcurrentTime
-XX:+PrintGCApplicationStoppedTime
You will need these logs to tune the JVM properly.
Note: To ensure you do have sufficient debugging information if your JVM encounters out of memory scenarios, you should consider adding this:
-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/dumps
Garbage collector log files can grow huge. Arguments like the ones below rotate the logging to a new file when the log file reaches a maximum size:
-XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10
-XX:GCLogFileSize=50M
These arguments rotate the logs to as many as 10 log files, each with a 50M
size limit.