Analyzing large Java heap dumps using Memory Analyzer CLI in Linux

Description:

When you have a situation or need to analyze really large heap dump (like 30/40 GB), then most of the times 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 analyzer tool in Linux

Pre-req to setup 

• Make sure you have enough physical / virtual (VM) memory available. (~at least equal to size of the file to make memory analyzer run smooth). 
• Make Sure you have tool downloaded from here http://www.eclipse.org/mat/downloads.php 
• Make sure you have necessary privileges or access on 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 dump analyzer
• ./ParseHeapDump.sh /dumps/heap.date.bin ls -vmargs -Xmx40g -XX:-UseGCOverheadLimit
• Xmx40g  - Here 40g represents allocated memory in GB for this process alter this as required.
• /dumps/heap.date.bin - This file represent 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 

• Above command will generate jvm_suspects.zip file which consists html files.
• Now these html reports can be shared with anybody by scp/email/ftp as required.