Re: [boost] Regex failures?

From: Roland Schwarz (roland.schwarz_at_[hidden])
Date: 2007-02-18 09:21:46

John, I am forwarding this to the list too.
Perhaps there is someone who might be able to help.

John Maddock wrote:
> Roland Schwarz wrote:
>> John Maddock wrote:
>>> Can you try running the .exe on it's own and see if it passes?
>>
>> I tried to run the very same executable built during the regression
>> test (msvc-7.1 stlport) from the command line:
>>
>> On my machine this needed about 9 minutes. I observed an interesting
>> fact though: Both cpu units (this is a hyperthreading cpu) were
>> saturated for some time then suddenly falling to 0% load and back
>> again to 100%. This switching between 0% and 100% was almost during
>> the whole test period.
>>
>> Finally the test passed. On the latest status pages I had 20 minutes
>> kill off time, but the test failed.
>>
>> So at the moment it seems as if the test only is failing when run from
>> regression.py.
> 
> :-(
> 
>> Btw.: Do you have an explanation for the observed behaviour (0%/100%)?
>> An additional note: The load was almost user space only.
> 
> No.  The test spawns 10 threads that each then run through the whole 
> test suite in parrellel, the aim is to really saturate the test and have 
> a good chance of getting failures if there are any threading issues that 
> have been missed. 

Could the observed behavior be an indication that there indeed is a real 
problem? One that shows up under certain conditions only, as e.g. the 
one we have?

> Could the 0% loads occur when waiting on a lock and 
> getting switched out to another process?  It stays at 100% on my single 
> CPU machine, and that's what I would expect to see, there certainly 
> aren't any deliberate waits going on.
> 
> I guess I could reduce the thread load and see if it clears the problem, 
> although it'll reduce the usefulness of the test as well unfortunately.
> 
> Many thanks for trying this out,
> 
> John.
> 

Roland