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javaprofilingyourkit

Yourkit Java Profiler: WALL TIME is probably measured incorrectly for Object.wait()

The initial problem I'm trying to solve is to see the wall times of all subcalls of a method across many threads. But I replicated my problem with a tiny application where I have a thread that executes one method that is mostly waiting as expected.

enter image description here

As you can see I'm specifically interested in pool-1-thread-2 executing method "com.sum.$Proxy10.uploadWaiting()" So I know for sure that this method spends most of its "WALL TIME" in getConnection() which goes down to Object.wait(long) But then I want to see what is the exact percentage​ of WALL TIME spent in getConnection() within com.sum.$Proxy10.uploadWaiting(). I go to "Method list" -> My Method->Merged Callees

enter image description here

As you can see getConnection() is only 1% of the total time of my method. And I have configured my sampling to do wall times for all methods. As you can see on the screenshot those are all marked as [Wall Time]. I'm using Yourkit 2015 build 15052.

Question: why doesn't getConnection() show something like 90%? Is it still calculating only CPU Time and not Wall Time?

Solution

  • Yourkit support answered my question and the answer is that I have to use

    -Dyjp.zero.time.methods=false

    in order to make the UI show the appropriate WALL TIME. It is true by default and overrides everything including the the wall time settings.

    The place where to put it is dependent on the Operating System and the version of Yourkit: https://www.yourkit.com/docs/kb/open_huge_snapshot.jsp For me (MacOS and Yourkit version 2015) it happened to be:

    <key>JVMOptions</key>
<array>
...
<!-- my fix to the UI-->
<string>-Dyjp.zero.time.methods=false</string>
</array>