Fwd: system profilers and incomplete stacks

[Roland Westrelin]

Forwarding to serviceability alias where this question belongs I think.

Begin forwarded message:

> From: Brendan Gregg <brendan.d.gregg at gmail.com>
> Subject: system profilers and incomplete stacks
> Date: June 12, 2014 at 7:15:54 PM GMT+2
> To: hotspot-compiler-dev at openjdk.java.net
> 
> G'Day,
> 
> Is there a way to run hotspot so that a system profiler (eg, DTrace, or Linux perf_events) can measure complete stacks? I often get incomplete, partial stacks, with one or a few frames only. I'm not worried about symbols right now, what I'd like is to walk stacks all the way down to thread start.
> 
> I've been browsing the hotspot code, but haven't found out how yet. I suspect it's related to Java optimized frames, and has ditched the frame pointer. I was looking for an equivalent -fno-omit-frame-pointer option.
> 
> Here's an example:
> 
> # dtrace -n 'profile-99 /execname == "java"/ { @[jstack(100, 8000)] = count(); }'
> [...]
>               org/mozilla/javascript/
> ScriptableObject.createSlot(Ljava/lang/String;II)Lorg/mozilla/javascript/ScriptableObject$Slot;*
>               0x884acce8200002da
>                 1
> 
>               sun/nio/ch/SocketChannelImpl.read(Ljava/nio/ByteBuffer;)I*
>               0xffffffff20007f4b
>                 1
> 
>               org/mozilla/javascript/ScriptRuntime.newObjectLiteral([Ljava/lang/Object;[Ljava/lang/Object;[ILorg/mozilla/javascript/Context;Lorg/mozilla/javascript/Scriptable;)Lorg/mozilla/javascript/Scriptable;*
>               0xa20000041
>                 1
> [...]
> 
> I see similar incomplete stacks with Linux perf_events. Oracle JDKs from 6 to 8, and OpenJDK.
> 
> thanks,
> 
> Brendan
> -- 
> http://www.brendangregg.com

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