Garbage Collection Analysis with HPJmeter

2 Sep

Introduction

HPJmeter is a tool that can be used to analyse garbage collection logs. HPJmeter is a useful tool to assist in identifying JVM issues.

How to use

  1. Download the tool from here to your machine
  2. Execute the jar file to open the application. Retrieve the garbage collection log (gc.log)  and save it somewhere to be opened by HPjmeter
  3. Go to Open File and select the gc file. You should get something that looks like this:

hpjmeter1

The summary view shows the overall statistics to do with GC and the heap. The screenshot below is the other main view ‘Heap Usage After GC’:hpjmeter2

This shows heap usage after GC and the garbage collection details. Pink indicates the JVM going into full GC.

General Trends

Typical

The below is an example of a typical/expected graph where memory increases but then reaches a point where heap usage drops again and this continues forming a ‘zig-zag’ or ‘sawtooth’ type patternhpjmeter3

Memory leak indicative

The below is an example indicative of memory issues where garbage collection goes and stays into full GC never able to release objects to decrease memory usage. When this happens there should be out of memory errors visible in the logs themselves.hpjmeter4

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