konser / heaplib

JVM Heap dump processing utility

HeapLib

HeapLib a tool/library for analyzing JVM heap dumps. HeapLib is using modified heap parser from Apache NetBeans (same library is used by VisualVM).

Main driver for this project was a need in automated analyzing of heap dump on remote servers.

In addition for original Heap class implementation from NetBeans library this project has an alteranative which:

• Works with heap dump file without any additional on disk files
• Process GZip compressed heap dump files directly
• Cannot calculate retained size or walk object references in backward direction

Besides an API, you can use executable jar for console to execute OQL/JavaScript.

Using HeapLib from Java code

HeapLib is a library you can use from Java code. You can find few examples in hprof-heap/src/test/java/org/gridkit/jvmtool/heapdump/example/ path formatted as JUnit tests.

Using HeapLib CLI

You can use executable jar to execute OQL/JavaScript scripts from console.

To get executable java build project with mvn clean package. Executable jar would be placed under name heap-cli/target/heap-cli-0.1-SNAPSHOT.jar.

Below few commands support by executable:

• java -jar heap-cli-*.jar --commands print list of supported command
• java -jar heap-cli-*.jar histo -d dump.hprof produce class histogram from path
• java -jar heap-cli-*.jar exec --noindex -d dump.hprof -j script.oql execute script on heap dump open in diskless mode (no on-disk indexes should be generated)

Few script examples could be would under hprof-oql-engine/src/test/resources/oql/ path.