java

Taking heap dump of java process on linux and windows

Taking a heap dump from console when Java VisualVM and JMX is not available to us.
We will use following tools

    • jmap
    • jps
    • ps

Dumping heap requires two steps
1) Obtaining target process id
2) Dumping heap for given pid

First we need to obtain the target process id we would like to dump, here I will show couple ways I like to use.

ps aux | grep 'java'
-----
userx     29901  6.7 47.0 25418812 3848276 ?    Sl   Mar23  85:42 /opt/java/bin/java -Djava.util.logging.config.

Here second column indicates our process id (pid)

Second method that is quite useful to obtain pid for java processes

uxserx@WS4:/opt/java/bin# ./jps -l
4281 sun.tools.jps.Jps
29901 org.apache.catalina.startup.Bootstrap

As we see both methods returned us pid of 29901
Npw to perform the dump we issue our second command

userx@WS4:/opt/java/bin# ./jmap -dump:format=b,file=/tmp/heapdump-001.hprof 29901
Dumping heap to /tmp/heapdump-001.hprof ...

At this point we have our heap dump that is ready to be analyzed, for my analysis I use two tools. Eclipse Memory Analyzer (MAT) and Java Visual VM

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