wrong phase duration in WPG report summary

Alex Rousskov rousskov at measurement-factory.com
Wed Mar 2 22:21:22 UTC 2016

On 03/02/2016 12:27 PM, Sanjeevi Rangan wrote:

> I have done few tests using WPG client and server with multiple phases
> (10min + 60min + 10min) and generated WPG report by feeding both client
> and server logs to the reporter tool . During initial 10 mins the number
> of concurrent connections would increase from 0 to max, the next 60 mins
> would maintain the max number of concurrent connections and the in the
> last 10 mins, the concurrent connection would decrease from max to 0. In
> some tests, the executive summary table on the index page would report
> duration as '10 min' and in some other tests, the duration value is
> '1.00 hour' (60 mins, which is expected).

This instability might be attributed to the actual peak request rates of
the two phases being very close. Polygraph is just guessing which phase
is more important to you...

> If the duration is '10 min' then the other metrics data on the table
> like response time and throughput would have values related to the
> transactions that happened during that 10mins. 

> I would like to know what determines the phase duration in the report.

The reported duration is the total measured duration of the phase(s)
selected for the executive summary and the baseline report. What you
probably want to know is which phase(s) are selected for the executive
summary and the baseline report :-).

By default, Polygraph currently selects the first phase with the highest
measured request rate. There is a 1% fuzz that is used when comparing
request rates, but when measured peak request rates are close, it may
not be enough to produce stable guesses.

Consider avoiding this uncertainty by configuring which PGL Phase(s) are
the primary ones. Here is an excerpt from the v4.0.6 change.log:

> - Added a PGL Phase.primary boolean field. If any of the phases
>   have that field set, those phases and only those phases should
>   be used for the executive summary and the baseline report. The
>   new field is logged when phase stats are logged.

You can also specify the primary phases during report generation, using
the --phases command line parameter for the reporter tool. Naturally,
the reporter parameter overwrites PGL configuration so you can produce
multiple reports with different executive summaries using the same set
of logs.



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