>> 
> 
> I think you have missed the point of my posting.
 
No, I just got excited that the problem is finally being looked at again 8*)

> 
> The idea was to detect when CO has happened, and use that information
> to change the test setup.

I just wouldn't fail a test based on it occurring. A result is a result and 
should be treated as such.. good or bad... Instead I'd offer a correction. In 
this case the correction would be to detect when the sampler should have been 
fired and add that time to the response time. I might flag a test saying that 
you didn't maintain a rate of throughput because of CO.

My problem with the threading model is that response times are upper bounded by 
a value that is a function of the number of threads. This can result in JMeter 
having unwanted effects on response times.

> In some cases it may not be possible avoid the CO, but in other cases,
> it should be possible to reduce the transaction rate in each thread
> such that long sample times don't cause the next sample to be delayed.

I think the way around CO due to threads not being available is to simply not 
reuse them. Since I've been using JMeter that way I find that my tests are 
working much better.
HTTP is sync which means I'm not sure about how to fix the problem that Gil is 
taking about without a very serious work around.

> And at least the user will have the required information.
> 
> So, I'll ask again: is my proposal for *detecting* CO reasonable?
> If not, what changes are needed?

I think detection is reasonable.. it's how the problem is dealt with afterwards 
is something that needs discussion.
> 
> Changing JMeter to behave differently is a matter for a separate thread.

Since the problems are coupled together I'd take this as a tactical hack to 
start to deal with the problem... which is a good start!

Thanks,
Kirk

> 
>> Regards,
>> Kirk
>> 
>> 
>> On 2013-10-18, at 12:27 AM, sebb <[email protected]> wrote:
>> 
>>> It looks to be quite difficult to avoid the issue of Coordination
>>> Omission without a major redesign of JMeter.
>>> 
>>> However, it may be a lot easier to detect when the condition has occurred.
>>> This would potentially allow the test settings to be changed to reduce
>>> or eliminate the occurrences - e.g. by increasing the number of
>>> threads or spreading the load across more JMeter instances.
>>> 
>>> The Constant Throughput Controller calculates the desired wait time,
>>> and if this is less than zero - i.e. a sample should already have been
>>> generated - it could trigger the creation of a failed Assertion
>>> showing the time difference.
>>> 
>>> Would this be sufficient to detect all CO occurrences?
>>> If not, what other metric needs to be checked?
>>> 
>>> Even if it is not the only possible cause, would it be useful as a
>>> starting point?
>>> 
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>> 
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