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Stack traces of blocked threads not shown

Moderators: Vladimir Kondratyev, Anton Katilin

Stack traces of blocked threads not shown

Postby robbo » Tue Nov 18, 2014 1:06 pm

Hi, I'm profiling a Java app (Java HotSpot(TM) 64-Bit Server VM; 1.6.0_45; 20.45-b01; mixed mode) on RHEL (2.6.18-194.32.1.el5) and YourKit is showing on the Threads tab a lot of red blocked threads. But in the bottom panel there are no stack traces - the [BLOCKED] threads just have java.lang.Thread.run(). VisualVM on the other hand shows the threads as idle, not blocked, most of the time. What is going on? Are these threads really blocked? Why won't it show me their stack traces? I can't make sense of what the Monitor Usage tab is telling me.
Thanks.
robbo
 
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Re: Stack traces of blocked threads not shown

Postby Anton Katilin » Tue Nov 18, 2014 2:25 pm

Hello,

Please change the "Details:" level to "Full stacks" (it's in the right upper corner of the "Stack traces" tab.)

Best regards,
Anton
Anton Katilin
 
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Re: Stack traces of blocked threads not shown

Postby robbo » Thu Nov 20, 2014 1:19 pm

Thanks Anton. My threads are now shown as BLOCKED on java.lang.Object.wait(long). But other threads are shown as WAITING on java.lang.Object.wait(long). What is the difference? It seems a bit misleading for it to tell me I have a load of threads blocked if they are just waiting. I thought I had a lock contention problem.
robbo
 
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Joined: Tue Nov 18, 2014 12:58 pm

Re: Stack traces of blocked threads not shown

Postby Anton Katilin » Thu Nov 20, 2014 4:16 pm

The thread statuses are reported by JVM. The profiler shows them as is.

Please use Monitors profiling to investigate thread contention:
http://www.yourkit.com/docs/java/help/m ... filing.jsp
Anton Katilin
 
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Re: Stack traces of blocked threads not shown

Postby Anton Katilin » Thu Nov 20, 2014 4:16 pm

Do you use the latest version of the profiler?
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