How to get Java profiling dump for creating flame graphs on Mac?

Question

I would like to collect stacktraces from my Java application to create graphics processor plugins for profiling.

This is very similar to this question: How to get a full stack dump from the profiler in each example for use in a flame graph? with 2 differences:

• I work with Java code and I need a Java stack stack
• I am working on a Mac (this means that there is no pref and AFAIK dtrace on OSX does not support the jstack extension).

I have already tried lightweight-java-profiler and Honest profiler , and both of them seem to not work on Mac. I also tried VisualVM , but I could not get it to create stacktrace dumps that I needed.

The first prioirty for me is flame graphs created from the Java stack, but having my own set of calls would also be great because it allowed me to address I / O issues (and possibly even generate hot / cold flame graphs ).

Answer 1

I created 2 small shell scripts based on @cello's answer. They generate hot / cold flame graphics .

Get them from this gist .

Using:

 ps ax | grep java # find the PID of your process ./profile.sh 20402 stacks.txt ./gen.sh stacks.txt 

Alternatively, to measure the application from starting (in this case, in my gradle assembly, which also needed to be run in a different directory and with some input stream), I used:

 cd ../my-project; ./gradlew --no-daemon clean build < /dev/zero &; cd -; ./profile.sh $! stacks.txt ./gen.sh stacks.txt 

Results:

In this example, I can clearly see that my application is connected with I / O (note the blue bars at the top).

Answer 2

Try the following: https://github.com/saquibkhan/javaFlameGraph

Installation

npm install javaflamegraph

Using

• cd javaflamegraph
• npm start - This will wait until it detects a process named "Java". It is best to use the start of profiling in the launch program.
• npm run start <process id> - This will start profiling for the given process id. e.g. npm run start 1234

Answer 3

Have you tried the jstack command? just run it on the command line: jstack pidOfJavaProcess > stack.txt (naturally, replacing pidOfJavaProcess with the actual process number). You can run this in a loop in bash (the default shell used on Mac OS X):

 while true; do jstack pidOfJavaProcess >> stack.txt; sleep 1.0; done 

pay attention to >> to add to the file, and not to overwrite it every second. Press Ctrl+C to stop recording stack traces.

This will only generate Java stack traces, and not native call stacks from the JVM.

Answer 4

The good news: there is a “script” for working with jstacks in the FlameGraph repository.

https://github.com/brendangregg/FlameGraph

This is stackcollapse-jstack.pl .

It seems that by default it only expects a stack trace after a stack trace at its input and considers each of them to be a "fetch point".

That way, you can just do a few jstack in a file (run this one or more times, or once per second "for a while", etc.):

jstack pid_of_your_jvm >> my_jstack

Then run this script:

  ./stackcollapse-jstack.pl my_jstack > my_jstack.folded 

and finally convert to flameograph:

  ./flamegraph.pl --color=java my_jstack.folded > my_jstack.svg 

No third-party helpers are required (although they can still be useful).

Also note that non-RUNNABLE threads are discarded in the stackcollapse-jstack.pl file, you can configure it if you also want to enable “unoccupied” threads (this is usually not the case).

Apparently you can use the linux "perf" command to generate stacks for the Java process, and also see README https://github.com/brendangregg/FlameGraph

This may include more of your own calls, for example.