Analyzing large Java heap dumps using Memory Analyzer CLI in Linux

Description:

When you have a situation or need to analyze a really large heap dump (like 30/40 GB), then most of the time MAT UI will fail to analyze such large files, in that case, you can use Memory Analyzer CLI in Linux/Windows. In this post, we will see how we use the analyzer tool in Linux

Pre-req to setup

Make sure you have enough physical/virtual (VM) memory available. (~at least equal to the size of the file to make memory analyzer run smooth).
Make Sure you have the tool downloaded from here http://www.eclipse.org/mat/downloads.php
Make sure you have the necessary privileges or access to the Linux system.

Steps to Follow

unzip download memory analyzer tool using unzip command
- unzip MemoryAnalyzer-1.7.0.20170613-linux.gtk.x86_64.zip
mat folder will be created then run “cd mat”
Run command to start to dump analyzer
- ./ParseHeapDump.sh /dumps/heap.date.bin ls -vmargs -Xmx40g -XX:-UseGCOverheadLimit
  - Xmx40g – Here 40g represents allocated memory in GB for this process alters this as required.
  - /dumps/heap.date.bin – This file represents your dump file alter the filename with full path in it as required.
Above command will take time based on the size of the dump file and it will generate index files on the directory where your dump file exists
Now to generate html files run below command
- ./ParseHeapDump.sh /dumps/heap.date.bin org.eclipse.mat.api:suspects
  - org.eclipse.mat.api:suspects – represents report type
  - Below are the other report types available

org.eclipse.mat.api:suspects
org.eclipse.mat.api:overview
org.eclipse.mat.api:top_components

The above command will generate the jvm_suspects.zip file which consists of html files.
Now, these Html reports can be shared with anybody by SCP/email/FTP as required.