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Help understanding the CPU view

Moderators: Vladimir Kondratyev, Anton Katilin

Help understanding the CPU view

Postby merz » Thu Jul 02, 2015 12:19 pm


Why does the CPU view contains just a few threads ?

Example, this snapshot was taken with the default settings (sampling_period_ms=20)

And here is the thread view (without internal threads) of this snapshot:

For example the CPU view does not contains:
- "SocketServer_/"
- "Swing-Shell"
- "Thread-115"

Posts: 1
Joined: Thu Jul 02, 2015 10:03 am

Re: Help understanding the CPU view

Postby Anton Katilin » Thu Jul 02, 2015 3:18 pm


The first picture shows CPU sampling results. They include only the threads for which non-zero CPU time has been measured. Threads with zero CPU time, i.e. most of their time being in the waiting state, will not be included. Please see the second picture - many of the threads indeed have zero time.

Also, please note there is a pseudo-thread "<Oldest finished threads>". By default, CPU profiling (i.e. of CPU sampling or CPU tracing) results are kept for up to 50 recent finished threads; results of older finished threads are merged to "<Oldest finished threads>". This limit is controlled with the startup option "deadthreadlimit": https://www.yourkit.com/docs/java/help/ ... ptions.jsp

Please note that the second picture shows a telemetry graph. Telemetry buffer is 1 hour by default - see startup option "telemetrylimit".

Best regards,
Anton Katilin
Posts: 5613
Joined: Wed Aug 11, 2004 8:37 am

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