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YourKit Java Profiler and .NET Profiler Forums :: View topic - Mustang b71/b73 + YP 5.1: 1000s of JNI Local GC roots

Environment: -Win32 -Mustang b73 -YP 5.1 -Tomcat 5.5.15 A typical snapshot contains 1000s or even 10000s of GC roots of type JNI Local. Is it a JVM regression, or is YP to blame?

Roots are shown exactly as they are reported by JVM. So this must be a JDK issue. Do you have similar number of such roots profiling with other JDK?

Anton Quote: : Do you have similar number of such roots profiling with other JDK? No.

I'll do an experiment with older Mustang builds.

I tried the following Mustang build: 69, 70, 71, 73 I tried different versions of Tomcat: 5.5.9 and 5.5.15 Version of YourKit used was always 5.1 All combination exhibit the same symptoms: excessive amounts of JNI Local GC roots.

In our application, the number of reported GC roots was around 15000. I'll try to verify this again on a completely clean system. p.s.

What is the "Held by JVM" GC root type?

I often see this for classloader instances.

I'd like to tese with earlier releases, but the build history on java.net only goes back to build 69. Using 1.5.0 releases before update 7 has other JVMTI issues.

(Some reported on this forum)

I've used 1.6 b74 and b64 for testing.

(Using JVMTI) Target application was a simple 4K Java game: http://javaunlimited.net/games/view.php?id=102 YourKit 5.1 shows +/- 1300 JNI Local GC roots. I'm pretty sure that 5.0.x releases did not exhibit this problem.

Are these releases archived somewhere?

Actually, this problem also occurs when using the last GA JRE: 1.5.0 update 6. Taking a snapshot of the minimal application mentioned above gives such results. Unless something is broken in my local JVM or YourKit installation it seems like a YK bug.

Can you provide the small application wich demonstrate the problem?

I'll try to prepare a testcase in the next few days.

It looks like I have managed to reproduce this. We're investigating the problem.

This problem is solved in 5.1.1 It is available at http://www.yourkit.com/download

5.1.1 does indeed fix the issue I saw, thanks for the rapid response.




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