system profilers and incomplete stacks

[Staffan Larsen]

I think this is the bug you are looking at: https://bugs.openjdk.java.net/browse/JDK-7187999, but I’ll defer to someone else to confirm.

/Staffan


On 16 jun 2014, at 12:47, Roland Westrelin <roland.westrelin at oracle.com> wrote:

> 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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