Note: This example is based on the Oracle JVM implementation.
Built-in tools like
jvisualvm are available in a JDK and can be used to generate and analyze heap memory dumps taken from a running JVM application. However, one option to generate a heap dump without using JDK tools is to add the VM argument
-XX:+HeapDumpOnOutOfMemoryError which tells the JVM to automatically generate a heap dump when an OutOfMemoryError occurs, and the argument
-XX:HeapDumpPath to specify the path for the heap dump.
Also see: Java HotSpot VM Options, specifically:
-XX:HeapDumpPath=./java_pid.hprof Path to directory or filename for heap dump. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.)
-XX:-HeapDumpOnOutOfMemoryError Dump heap to file when java.lang.OutOfMemoryError is thrown. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.)
If a concurrent collector such as CMS or G1 are used then a FullGC can be considered a failure mode and using
HeapDumpAfterFullGC can be useful to diagnose them.