[Mondrian] Changing the mondrian development process to prevent performance slippages

John V. Sichi jsichi at gmail.com
Tue Apr 1 14:48:31 EDT 2008


LucidEra's setup is fairly similar to what Matt describes.  We run a 
full stack (Grinder simulating browser clients sending XML report 
requests; ClearView->Mondrian->LucidDB on the server side, where 
ClearView is LucidEra's AJAX UI).  For the concurrency tests, one 
configuration runs with periodic cache flushing to simulate a real-world 
environment where the reports aren't the same every time.  We vary 
configurations by number of concurrent simulated users for 
concurrency/throughput testing.

This has helped us catch many issues with Mondrian (both correctness and 
performance).  We branch Mondrian in Perforce for each LucidEra release 
so that we can stabilize and maintain it, and then do perf testing 
against the mainline to know when we can safely sync back up to it for 
the next release.  So as with Thomson, we don't track the effect of 
every Mondrian change (although sometimes we have to do comparative runs 
with and without selected changes to identify a culprit).

For direct Mondrian-level testing, maybe a full client/server setup 
would be overkill.  Perhaps the concurrency test suite contributed by 
Khanh Vu could be used as a basis for the multi-user performance 
simulation (with configurability added for disabling correctness testing 
to achieve high throughput, on the assumption that a correctness suite 
runs separately)?  It includes some cache-flushing and mem-hungry scenarios.

JVS

Matt Campbell wrote:
> 
> At Thomson we have a performance test suite that we run semi-regularly.  
> The suite involves a set of Cognos reports designed to be representative 
> of typical use of the system.  All reports are run in a "clean", 
> 3-tiered environment where no other activity is happening.  We typically 
> run both sequential sets of tests as well as concurrent tests.  We then 
> collect report run times and compare to the previous run. For some test 
> runs we also collect CPU and memory statistics.  In the past these test 
> results have clued us in to issues with Cognos, with our system 
> configuration, our custom jdbc driver, and occasionally Mondrian.
> 
> Our tests have not been run regularly enough to catch Mondrian 
> performance problems when they happen, however.  We don't integrate 
> every revision of Mondrian into our system, so it may not be clear what 
> change actually introduced an issue.
> 
> What I would love to see is a nightly test suite that runs a set of 
> queries with multiple configurations, collects timings, and then dumps a 
> report to somewhere accessible.  Even better would be to run it as part 
> of the cruise and report back a % difference after each checkin, but 
> that's probably not feasible if we want to test a large variety of 
> configurations.  Either way, if we can get % difference information on a 
> regular basis we can react more quickly to new issues.
> 
> Simply defining a set of queries and incorporating them into a separate 
> JUnit test suite might be a step in the right direction. 
> 
> 
> 
> 
> 
> 
> On Sun, Mar 30, 2008 at 8:00 PM, Julian Hyde <jhyde at pentaho.org 
> <mailto:jhyde at pentaho.org>> wrote:
> 
>      > John Sichi wrote:
>      >
>      > RE: [Mondrian] Adding Grouping Set support for Distinct Count
>     measures
>      >
>      > In eigenchange 10766, I changed AggregateFunDef to allow it
>      > to skip the
>      > list reduction methods added by Ajit (on a per dialect
>      > basis), because
>      > they are really slow.
> 
>     I'm beginning to think that I need to start running a tighter ship as
>     regards performance. There have been several alleged performance
>     slippages
>     over the past year, but we've not caught them effectively. Our
>     process is
>     not strong enough to detect them at the time they are made, and
>     after the
>     event it is too difficult to figure out which change out of many caused
>     performance to sutffer.
> 
>     So, please, I'd like to hear suggestions for how we can change our
>     process.
>     It can't be purely a process change, because I don't personally have
>     enough
>     time/discipline to review each change as it is made and test its
>     performance
>     effects; there has to be some technology involved. Developers are
>     responsible for ensuring that their change doesn't degrade
>     performance, even
>     on platforms that are not of interest to them personally, but it isn't
>     enforced, so slippages occur. So we need a way to enforce that
>     changes don't
>     degrade performance, just as we have a regression suite to ensure
>     that other
>     aspects of mondrian's behavior are preserved.
> 
>     Since LucidEra and Thomson/Thoughtworks are the two largest groups
>     besides
>     Pentaho who have an interest in developing mondrian, I would like
>     those two
>     groups in particular to step up with suggestions and offers of help.
>     Pentaho
>     can provide resources to run the process and publish results, but
>     can only
>     offer limited leadership.
> 
>     Julian
> 
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> 
> 
> 
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