Apparent deadlock when running in Sampling mode

Code profiling for .NET developers.

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Apparent deadlock when running in Sampling mode

Postby swythan » Mon May 13, 2013 12:16 pm

I'm trying to profile my app on and I can't get it to work in Sampling mode. Every time I try, my application appears to deadlock once it hits the code that I'm actually trying to profile. That is: CPU usage goes 0% and the program stops making progress.

The code I'm trying to use is using a lot of Parallel.For loops and Tasks, and I'm running on a system with 2x Intel Xeon E5-2665 CPUs, for a total of 32 logical cores (16 physical w/ hyper-threading). WinDbg shows that I have 61 .Net threads at the point of deadlock, with quite a few of them at :
Code: Select all
RedGate_Profiler_Core!ANTS_Leaving_Sql+0x419ef


Any ideas? I'm happy to poke around some more with WinDbg, if that helps.

Thanks!

P.S. Line & Method-level timings work OK, but the CPU usage pattern I get is quite different from when I'm running without the profiler, so that's no good to me. I really need to get sampling-based profiling working. VS2012's sampling mode works, but that doesn't easily give me the "what method is running when" info that ANTS does.
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Postby james.billings » Tue May 14, 2013 1:16 pm

Thanks for your post- is it possible for you to supply the memory dump to us for analysis?

If it zips up pretty small, please email it to support@red-gate.com along with "F0072862" in the subject line. If it's still pretty large then I can set up some FTP space if you have nowhere else for it to go... feel free to email us with the above ref. in any case.
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I am seeing the same thing in 8.3.0.8

Postby seanhalliday » Wed Oct 09, 2013 3:58 pm

Application regularly hangs when in sampling mode and ANTS profiling just flatlines with "Blocked" as the only info when I select regions of the timeline.
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Experiencing the same issue

Postby cesar.fernandes » Mon Oct 14, 2013 1:28 pm

I am having the same issue reported at this thread. I am seeing exactly the same behaviour as seanhalliday.

Is there any solution for it? I haven't tried the other profiling methods, do they work?

Thanks in advance
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I am seeing the same thing in 8.3.0.8

Postby seanhalliday » Tue Oct 15, 2013 5:22 pm

@cesar.fernandes - I have not seen this issue with other profiling methods.
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Postby jessica.ramos » Wed Oct 16, 2013 5:10 pm

Hi seanhalliday and cesar.fernandes,

So sorry to hear you've run into this issue!

Could you each drop us a line at support@red-gate.com so we can open up tickets for you both and investigate this deadlock problem?

Ideally, we'd like to get a copies of your applications and/or hang dump files to really understand what's going wrong.

Thanks!
Jessica Ramos
Technical Support
Red Gate Software Ltd.
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Postby Chris.Allen » Thu Oct 17, 2013 5:46 pm

Curiously- this is an access denied exception from:

System.Diagnostics.ProcessManager.OpenProcess(System.Int32,System.Int32,System.Boolean)
System.Diagnostics.Process.GetProcessHandle(System.Diagnostics.Process,System.Int32,System.Boolean)
System.Diagnostics.Process.get_HasExited(System.Diagnostics.Process)
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