jmeter-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From James Liang <>
Subject RE: Debug PostProcessor output interfere with Regular Expression Extractor
Date Tue, 10 Dec 2013 23:01:18 GMT
Hi Sebb and Philippe,

Thank you very much for helping me out with this issue.

Let me first address the main issue that I see and then your suggestions further below.

I think a fundamental design guideline that is important to adhere to is this:  

Debug aids should not interfere with correct application behavior.  Otherwise the system will
have obscure landmines that can be very painful.  Just imagine what if your java debugger
have the same problem...

Unfortunately, the Debug PostProcessor breaks this rule.  Maybe one simple fix is to get rid
of the DebugPP.  Instead, add a debug tab to the View Results Tree listener.  The debug tab
will display the Sampler Properties and JmeterVariables.

Regarding your suggestions: 

1) Use Debug Sampler instead:

The problem with the Debug Sampler is that it is not a preprocessor; it is a sampler.  As
such I have to manually add it before every sampler.  I have a bunch of long test scenarios
which make this tedious.  By using the Debug PostProcessor, I just need to add one inside
the Thread Group and it gets invoked after every sampler.  

Also, I wouldn't be surprise if the regex extractors also works on Debug Sampler output as
well.  If so, we'll end up with the same problem.

2) Reordering the DebugPP to the end:

Here is the hierarchy of my test.  Notice the Debug PP is already at the bottom.  

Thread Group
-- http request sampler A
-- While Controller
---- http request sampler B
------ regex extractor
-- Debug Post Processor

I've also tried moving Debug PP to in front of "http request sampler A" and the test still
doesn't work.  

James Liang

-----Original Message-----
From: sebb [] 
Sent: Monday, December 09, 2013 2:16 AM
Subject: Re: Debug PostProcessor output interfere with Regular Expression Extractor

Why are you using the PostProcessor?

I would have thought the Debug Sampler would have been more suitable, and that can be added
after the sampler to which the Regex is attached. This guarantees it is after the Regex PP

As already suggested, ensuring the Debug PP is last should also help - in fact, without doing
that, surely it won't show the result of of the Regex PP?

On 8 December 2013 19:28, Philippe Mouawad <> wrote:
> Hello,
> What if you put Debug Post Processor as last child of parent ?
> Regards
> Philippe
> On Sunday, December 8, 2013, James Liang wrote:
>> Hi,
>> I've setup a Regular Expression Extractor to handle Main sample and 
>> sub-samples.  This is necessary to handle any redirects.  I also 
>> added a Debug Postprocessor to help troubleshoot.  Because the Debug 
>> PostProcessor automatically becomes a sub-sample of a samplers, the 
>> Regular Expression Extractor automatically included the Debug 
>> PostProcessor output in the extraction!  In this setup, the Regular 
>> Expression Extractor includes both the normal response from the web server and debug
>> This bug has caused me more than a day to track down.
>> Couple of suggestions:
>> 1)      Since the Debug PostProcessor is a special processor for debugging
>> only, its output should not have been included in the Regular 
>> Expression Extractor.
>> 2)      It would be very helpful if the document on the Debug
>> PostProcessor has a warning on this serious side effect.
>> stProcessor
>> Thanks,
>> James Liang
> --
> Cordialement.
> Philippe Mouawad.

View raw message