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.

Installation and Setup Jenkins on Centos 7.x

Preparing Node (CenOS)

• Setup Appropriate Hostname with FQDN

          echo "jenkins.rulepaper.com" > /etc/hostname

• Install wget if your node installed with minimal OS installation

          sudo yum install wget -y

• Install Java if it is not already exists

          sudo yum install java -y

• Update system 

     sudo yum update

Installation of a stable Jenkins version

• sudo wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat-stable/jenkins.repo

• sudo rpm --import https://jenkins-ci.org/redhat/jenkins-ci.org.key

• sudo yum install jenkins -y

• set the jenkins service to start while booting "sudo chkconfig jenkins on"

• Start the jnekins service "service jenkins start"

Configuration of Jenkins

• Open Jenkins home page using your favourite browser http://hostname:8080 or http://ip-address:8080 

• As mentioned in above pic, get your secure password from mentioned file using cat /var/lib/jenkins/secrets/initialAdminPassword

• After validating your secret password, page will proceed wot SetupWizard

• You can select "install suggested Plugin" option to proceed with plugin installation.

• Suggested plugin installation will start and right side you will see installation status.
• Post installation it will prompt us to create first admin user.

• File the user details and click on "Save and Continue", followed by instance configuration click on "Save and Finish".

• Now Jenkins is ready to start using it click on "Start using Jenkins".

• It will take you to the Jenkins home page.

Will post a video soon on about "Explore Jenkins in Realtime"