Thread dumps are often needed to diagnose the application performance issue like deadlocks, hung threads, and bottlenecks in Java threads.
Taking Thread Dumps in WebSphere
It’s recommended to take multiple thread dumps in 5-8 seconds. You can use any of the following methods to generate it.
1. Using wsadmin.sh
Login into WAS Server
Go to profile and bin folder
Execute wsadmin.sh file
[root@localhost bin]# ./wsadmin.sh
WASX7209I: Connected to process "dmgr" on node localhostCellManager01 using SOAP connector; The type of process is: DeploymentManager
WASX7029I: For help, enter: "$Help help"
Set JVM name in a variable
set jvm [$AdminControl completeObjectName type=JVM,process=server1,*]
Note:server1 is, for example. Change this to your actual JVM name.
This will generate a thread dump and will be available under the profile path.
2. Using kill
Find the JVM process ID using ps command
Execute kill -3 $PID
# kill -3 $PID
You will find the dump in the profile path.
3. Using the WebSphere Administrative Console
Login into DMGR Console
Navigate to Troubleshooting at the left side
Select the JVM and click on “Java core.”
Once you have the thread dump, you can use the following tools to analyze them.
Analyzing WebSphere Thread Dumps
Analyzing dumps are always challenging, and following FREE tools will help you.
IBM Thread Dump Analyzer (TDA)
Using IBM TDA, you can identify hangs, deadlocks, and bottlenecks in Java threads.
You can download IBM TDA from here. It’s just the jar file, and once downloaded, you can execute the following to start the GUI.
java -jar jca457.jar
Click on File >> Open Thread Dumps
Browse the folder and select the dump you wish to analyze
It will take a few seconds, and you are all set to do the following analysis
User process resources limit
Shared class cache
All are available under the “Analysis” menu. A quick look at thread status analysis
So go through the analysis you are looking for have fun with IBM TDA.
So now, you should be able to generate and analyze the thread dumps for application troubleshooting. There is more analyzer explained here.
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IBM has released WebSphere Application Server 9 (WAS Classic) beta on their Cloud – Bluemix. Based on the initial announcement, it’s not known when it will be available as a full profile in downloadable installation but will be soon.