Sunday, July 18, 2010

Heap dump on a Unix machine

After exploring the Jay/Faisal's blog on 'jmap' java utility usage and Heap dump. It is really great work by Jay/Faisal. I just thought that similar kind of experiment we did long back on UNIX machines. I am glad to sharing that with you guys.

Last year, we were struggling to overcome the OutOfMemoryError, which would effect the most of productive hours. In this assignment I need to figure out what process is causing the low memory in the environment is identified by searching a all log files in the machine. Assume that all the WebLogic instance log files are collected into common directory structure, each of them are stored respective instance named folder.

Script 1:

After identifying the impacted instances, I need to take the heap dump of that particular instance with corresponding process id.

# File Name  :
# Author  : Pavan Devarakonda
# Purpose  : Script for searching all WebLogic instances logs in a box
instances=`ls /path/instances|grep web`
for x in $instances
        echo 'Checking in the :' $x
        cd /path/instances/$x/logs
        egrep -i $phrase instance*log
        egrep -i $phrase instance*out
# Know the CPU load average at this time

Script 2: Automatic script for Heap dump, here you need to provide the managed server name at the command-line argument. 

# Name    :
# Purpose : This script will takes instance name as input
# Takes the thread dump and also takes heap dump
if [ "$1" = "" ]; then
        echo "Usage : $0 "
        ppid=`ps -fu $user|grep $instance|grep startMan|grep -v grep|awk '{print $2}'`
        wpid=`ps -fu $user|grep $ppid|grep|awk '{print $2}'`
        jpid=`ps -fu $user|grep $wpid|grep java|awk '{print $2}'`
        echo 'The Java PID:' $jpid
        kill -3 $jpid
        if [ $jpid = "" ]; then
                echo "Invalid instance input..."
               jmap -dump:live,format=b,file=heap.bin $jpid
                mv heap.bin $instance_heap.bin

This could give you one more way of finding a java process in UNIX machine. You can use jps command instead of three lines of awk filters. In this same script to make hold the java process not to crash, we can call a WLST script to suspend the instance and then you can happily take the heap dump.

What to do after heapdump creation?
Use jhat command to run the analyzer to show the outcome on a browser.
Follow the Faisal tips to find memory leaks, use eclipse MAT that is comfortable for your system.


Blurb about this blog

Blurb about this blog

Essential Middleware Administration takes in-depth look at the fundamental relationship between Middleware and Operating Environment such as Solaris or Linux, HP-UX. Scope of this blog is associated with beginner or an experienced Middleware Team members, Middleware developer, Middleware Architects, you will be able to apply any of these automation scripts which are takeaways, because they are generalized it is like ready to use. Most of the experimented scripts are implemented in production environments.
You have any ideas for Contributing to a Middleware Admin? mail to me