Generate Heap Dump using java Visual VM

• A Heap Dump is a snapshot of the Java process heap memory at a given time

• It is a useful tool to troubleshoot memory leaks and other memory related issues

• Heap Dump is used to analyse the objects state in a JVM ,usually we analyse Heap Dump during out of memory error

Steps:

• Go to $JAVA_HOME/bin

• Run the command ./jvisualvm

    

Invoking Visual VM from the Java Installation

• After running the command ./jvisualvm command it automatically opens java VisualVM  window

Java VisualVM

• Next open the process id(pid)

Open the MBean by selecting  WebLogic Pid

• Click on Monitor Tab --> Heap Dump Tab

Click on Heap Dump Tab

• Click on classes then Java VisualVM enables us to browse Heap Dumps as shown below with the classes view where we can identify the number and percentage of instances referred by each class.

Percentage of instances referred by each class

Generate Thread Dumps in WebLogic 12C using WLST & Admin Console

Thread Dump is a snapshot of the state of all Threads That are part of the process.

Thread dumps are one of the very important JVM reports , which we can use to analyse server/JVM hang situations and the root cause of it.

Pre - requisites for this experiment:

• WebLogic installed
• Domain Configuration
• AdminServer,Managed Servers Running state

There are 2 ways to Generate Thread Dumps in WebLogic:

1) From WebLogic Admin Console

2) Using WLST commands

1) ThreadDump from WebLogic Admin Console:

• Open Servers tab in Admin Console
• Select Admin/Managed Servers
• Select Monitoring -> Threads tab
• Then click on Thread Dump ->Dump Thread Stacks

Generating Thread Dumps using Admin Console

2) Using WLST commands:

• Set the CLASS PATH by using Environment variables("java weblogic.WLST") to connect WLST
• Then it will connect to wls:/offline> 
• connect("username","password","url:port")
• Example:  connect("weblogic","welcome1","192.168.136.128:7001")
• threadDump()

WLST:

Thread Dump using WLST

Output :  Thread Dump for AdminServer

Thread Dump for WebLogic AdminServer