JVM Memory Analysis

JVM Memory Analysis

Abstract

This wiki contains some notes on tools that we found useful when analysing the memory usage by Java applications.

Tools

jps - list the instrumented JVMs on the target system with their name and PID; this is one of the standard JDK utilities, available on the command line; refer to https://docs.oracle.com/en/java/javase/19/docs/specs/man/jps.html for more details.

jcmd – send diagnostic command requests to a running Java Virtual Machine (JVM); this is one of the standard JDK utilities, available on the command line; refer to https://docs.oracle.com/en/java/javase/19/docs/specs/man/jcmd.html for more details.

The jcmd utility can be used to capture the heap dump of a Java process: jcmd <pid> GC.heap_dump <file-path>.

For example, running jcmd 7232 GC.heap_dump heap.hprof would dump the heap of the Java process with PID 7232 to file heap.hprof.

The captured heap dump can be conveniently analysed by the Eclipse Memory Analyser (MAT), which can be found at https://www.eclipse.org/mat/.

And of course, one can use the Java Mission Control and Java Flight Recorder (https://github.com/openjdk/jmc).