RE: [cdt-debug-dev] multiple threads and call stack update

[Elena Laskavaia <ELaskavaia@xxxxxxx>]

I agree with that - so I asked Denis to submit a bug, I can see it happening
here with CDT 4.0.2 and I was surprised too. After I fix dead locks
performance would be the first thing I will look into fixing in CDT
debugger.

-----Original Message-----
From: cdt-debug-dev-bounces@xxxxxxxxxxx
[mailto:cdt-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of Stefan Bylund
Sent: January 16, 2008 11:56 AM
To: CDT Debug developers list
Subject: Re: [cdt-debug-dev] multiple threads and call stack update

Hi,

I remember that in Eclipse 2.x / CDT 2.x, the stack backtrace was 
retrieved for all threads; this seriously reduced the performance of 
single stepping if you had many threads.

In Eclipse 3.0-3.2 / CDT 3.x, the stack backtrace is only retrieved for 
the current thread and, if any, the expanded threads in the debug view; 
this greatly improves the performance of single stepping if you have 
many threads.

I haven't tried Eclipse 3.3 / CDT 4.x that much yet, but I would find it 
very disappointing if the stack backtrace behaviour has changed 
negatively compared to Eclipse 3.0-3.2 / CDT 3.x. IMHO, if Eclipse 3.3 / 
CDT 4.x tries to retrieve the stack backtrace for anything else than the 
current thread and any expanded threads in the debug view, I would call 
it a serious bug that needs fixing.

Regards,
Stefan


Denis PILAT wrote:

> Well, it might be not a bug.
> My environment is a C program hosted on linux.
>
> My point is just to understand why Eclipse behaves like that in the 
> current version. It requests the debugger for some information that 
> are not displayed, and in some cases, it could take more than 10 
> seconds to make a single step.
>
> I though we could first discuss that thru the mailing list ?
>
> Denis
>
>
>
> Elena Laskavaia wrote:
>
>> Please send a bug report if it is not already there and specify your
>> debugger and environment
>>
>> -----Original Message-----
>> From: cdt-debug-dev-bounces@xxxxxxxxxxx
>> [mailto:cdt-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of Denis PILAT
>> Sent: January 16, 2008 4:25 AM
>> To: CDT Debug developers list; cdt-dev@xxxxxxxxxxx
>> Subject: [cdt-debug-dev] multiple threads and call stack update
>> I have an application that creates around 100 threads.
>> On Eclipse 3.3, after a stepping operation, an update of the call 
>> stack is requested by Eclipse to the debugger for some of these threads.
>>
>> After the program stops, you can see with the verbose console mode 
>> something like:
>> [1,200,399,158,705] 649-thread-select 3
>> [1,200,399,158,732] 650-stack-list-frames 0 8
>> [1,200,399,159,169] 651-stack-list-frames 0 8
>> [1,200,399,159,181] 652-thread-select 103
>> [1,200,399,159,209] 653-thread-select 2
>> [1,200,399,159,235] 654-stack-info-depth
>> [1,200,399,159,329] 655-stack-info-depth
>> [1,200,399,159,330] 656-thread-select 103
>> [1,200,399,159,345] 657-thread-select 2
>> [1,200,399,159,371] 658-stack-list-frames 0 5
>> [1,200,399,159,480] 659-thread-select 103
>> [1,200,399,159,508] 660-thread-select 1
>> [1,200,399,159,532] 661-stack-info-depth
>> [1,200,399,159,536] 662-stack-info-depth
>> [1,200,399,159,538] 663-thread-select 103
>> [1,200,399,159,551] 664-thread-select 1
>> [1,200,399,159,574] 665-stack-list-frames 0 2
>> ...etc...
>>
>>
>> On Eclipse 3.2 only the current thread requested a call stack frame. 
>> Other thread requested an update only if they are selected in the 
>> debug view, and as threads in the debug view are all collapsed at 
>> each step (like in the 3.3 version),  that was much more optimized in 
>> term of number of requests done to the debugger.
>>
>>
>> Is the 3.3 behaviour a normal behaviour or a regression ?
>> I'm wondering why Eclipse requests call stack frame  for threads that 
>> are not expanded in the debug view ?
>> And why it requests that only for parts of the threads ?
>>
>>
>> Thanks for you answer
>> Denis PILAT / STMicroelectronics
>>
>>
>>
>>
>>
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>>
>>   
>
> _______________________________________________
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-- 
---------------------------------
Stefan Bylund
Senior Software Engineer
Enea
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Direct: +46 8 50 71 43 25
Mobile: +46 709 71 43 25
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