Snapshots contain no profiling information

Questions about YourKit Java Profiler
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Confused
Posts: 7
Joined: Wed Feb 10, 2016 3:51 pm

Snapshots contain no profiling information

Post by Confused »

Hi all,

I'm currently using yourkit to profile Hadoop mapreduce tasks, I've added the -agentpath to the correct file so that every map JVM is started with a profiler attached.

When the JVMs are shutdown I can see the snapshots in the output file (corresponding to the number of mapper JVMs that got started) but when I open the snapshots they are completely empty? (No trace information for CPU etc).
I even tried it for just 1 map JVM which took several minutes to complete but it is still empty and the file is only 7mb in size.

What could the problem be?
Anton Katilin
Posts: 6172
Joined: Wed Aug 11, 2004 8:37 am

Re: Snapshots contain no profiling information

Post by Anton Katilin »

Hi,

What options did you specify in -agentpath ?
Did you start CPU profiling with sampling or tracing?

Best regards,
Anton
Confused
Posts: 7
Joined: Wed Feb 10, 2016 3:51 pm

Re: Snapshots contain no profiling information

Post by Confused »

Hi Anton,

Here's my configuration -agentpath:/home/hduser/yourkit/yjp-2015-build-15086/bin/linux-x86-64/libyjpagent.so=tracing,dir=/home/hduser/Profiling_Results

Thanks
Anton Katilin
Posts: 6172
Joined: Wed Aug 11, 2004 8:37 am

Re: Snapshots contain no profiling information

Post by Anton Katilin »

Are you sure you apply -agentpath to the process that you want to profile, but not to another process that, for example, just launches other processes?

You may check this in the snapshot's Summary tab that contains the command line and other parameters.

To profile indirectly called processes you may specify -agentpath with the environment variable JAVA_TOOL_OPTIONS instead of specifying it in the command line of particular process.

If nothing helps could you please provide us with one of the problematic snapshots. If you cannot share it here could you please send it (or a download link) to [email protected]
Confused
Posts: 7
Joined: Wed Feb 10, 2016 3:51 pm

Re: Snapshots contain no profiling information

Post by Confused »

Hi Anton,

Sorry for the delay in my reply, I have looked at the snapshot summary but cannot see any information. Everything is labelled as just "unknown".

I used another open source JVM profiler to profile the same JVMs I am profiling with Yourkit and I get some data from the open source one. This leads me to believe I am profiling the correct JVM.

I have uploaded one of the many snapshot files I created and I have created a dropbox link: https://www.dropbox.com/s/f2ufxpbnn0vxk ... pshot?dl=0

Thanks very much for the help.

Regards
Anton Katilin
Posts: 6172
Joined: Wed Aug 11, 2004 8:37 am

Re: Snapshots contain no profiling information

Post by Anton Katilin »

The snapshot corresponds to a very short living - I think, less than a second, since no telemetry samples seem to have been registered - process. So this is really likely the wrong process you enable profiling of. Maybe the one that launches the real one.

I can suggest that you instead launch the server as usual, and then attach to the running instance:
https://www.yourkit.com/docs/java/help/ ... wizard.jsp
Confused
Posts: 7
Joined: Wed Feb 10, 2016 3:51 pm

Re: Snapshots contain no profiling information

Post by Confused »

Hi Anton,

Thanks for the help, I'll be sure to look into your tips and see if I can get the right JVM!
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