[MapProxy] SV: Response time question

Mon Apr 11 08:12:26 EDT 2011

Hi Johan!

Can you try to find out if your mapproxy setup is cpu or disk bound using
systat utilities?

Cpu monitoring: mpstat -P ALL 2
I/O monitoring:  iostat -xhm 2

If your mapproxy configuration is set up well the limiting factor should be
disk I/O. If you don't see high disk I/O utilization and only one cpu
utilized something is wrong with you WSGI configuration.

cu andreas

2011/4/11 Johan Sandberg <johs at kth.se>

>
> I am performing tests with the software LoadUI. I have pregenerated URLS
> from a listw which the programe reads.
> The backend WMS are a geoserver which is pretty fast. MapProxy is installed
> on a linux computer running on apache2 with the WGSImode.
>
> The test scenario are: 400*300, 800*600,1200*900 and 1600*1200 for 10
> concurrent users.
> Then test the 800*600 for 20,50 and 100 concurrent users.
>
> I test two different cases when the cache is seeded and when its
> dynamically filled.
>
> The results (avarage time milliseconds) on  directly to WMS and to seeded
> cache are as follows
>
> WMS 400*300 10 request/sec      1157,276546
> WMS 800*600 10 request/sec      2027,072179
> WMS 1200*900 10 request/sec     3463,510585
> WMS 1600*1200 10 request/sec    5571,929988
> WMS 800*600 20 request/sec      4045,260605
> WMS 800*600 50 request/sec      10349,9973
> WMS 800*600 100 requst/sec      20279,21129
>
>
> MapProxy 400*300 10 request/sec 229,7247875
> MapProxy 800*600 10 request/sec 1322,603837
> MapProxy 1200*900 10 request/sec        2753,405889
> MapProxy 1600*1200 10 request/sec       6793,848616
> MapProxy 800*600 20 request/sec 2678,599481
> MapProxy 800*600 50 request/sec 6545,8422
> MapProxy 800*600 100 request/sec        19226,09422
>
> For the fourth test (1600*1200) the WMS the avarage time is better for WMS
> than for MapProxy.
> The tests are fetching the same data which are severall vector layers
> compose as one Map layer.
>
> / johan
>
> ________________________________________
> Från: Rahkonen Jukka [Jukka.Rahkonen at mmmtike.fi]
> Skickat: den 11 april 2011 13:12
> Till: Johan Sandberg
> Kopia: mapproxy at lists.osgeo.org
> Ämne: Re: [MapProxy] SV: Response time question
>
> Hi,
>
> In my tests MapProxy has been either much or very much faster than my
> backend WMS but that depends on many things.  With extremely simple vector
> layers with simple styles and with just a few concurrent users my WMS can be
> almost as fast. Biggest speedup (at least ten times faster)is when rendering
> complicated vector layers like OpenStreetMap data at small scales . Speedup
> with raster maps or aerial images is something in between, let's say 5 to
> times faster.
>
> What is your use case like? What data you have on WMS (vectors/rasters)? I
> suppose you are testing with WMS calls. Do you use the same projection than
> your Mapproxy tiles are, or does Mapproxy do reprojection for you? How do
> you test, are you running the same script with reasonably many requests with
> jmeter or something?
>
> WMS can be a bit slow to start, especially Mapserver in CGI mode is such.
> Therefore it is normal that throughput as bits per second with big WMS
> requests is higher than with small requests but this depends on the WMS
> software and also on the data. Mapproxy, on the other hand, is using
> prerendered tiles of fixed size as a raw material and therefore it is
> showing a very stable throughput with varying image sizes. With the backend
> data it is naturally totally ignorant (when serving from the cache), heavy
> OSM tiles are rendered just as fast as a simple point layer. This is also
> making it easier to manage the WMS server. It is not so important to use all
> the tricks I know for making the heavy WMS bulk layers 10 per cent faster
> because WMS is used just once after each update and thereafter Mapproxy is
> taking the load.
>
> Can you give any exact numbers about your tests? How many 400x300 sized
> images per second you can get out from your WMS and how many through
> Mapproxy?
>
> Johan Sandberg wrote:
>
> > Hej!
> > Yes that's offcourse true. This leads to not so greate
> > performance on bigger image sizes with Map Proxy.
> > Measuring directly to the WMS I see that the scaling is only
> > twice the time.
> > To a certain image size there is no use of using M.P for
> > better perfromance according to the tests I perform.
> >
> > / Johan
> > ________________________________________
> > Från: Rahkonen Jukka [Jukka.Rahkonen at mmmtike.fi]
> > Skickat: den 11 april 2011 11:07
> > Till: Johan Sandberg
> > Kopia: mapproxy at lists.osgeo.org
> > Ämne: Re: [MapProxy] SV: Response time question
> >
> > Hi,
> >
> > He means that if you'll take four times more pixels
> > (800x600=480000 vs 400x300=120000)
> > then you'll need approximately four times longer time.
> > Rather logical and to my experience pretty accurate approximation.
> >
> > -Jukka Rahkonen-
> >
> >
> >
> > Johan Sandberg wrote:
> > >
> > > Hej!
> > >
> > > "MapProxy should scale linear with the number of pixels. So
> > > you should expect 1/4 requests when changing from 400x300 to
> > > 800x600. You should measure the times with one concurrent
> > > requests at first and then you should look how you can scale
> > > that with increased concurrency, see below."
> > >
> > > So do you mean that I could expect four times the time to
> > > fetch an image that comes from seeded tiles when the
> > > requested image size double?
> > >
> > > Is there any good documenations on this? Would be pretty helpful!
> > >
> > > / Johan
> > >
> > >
> > > ________________________________________
> > > Från: Oliver Tonnhofer [olt at omniscale.de]
> > > Skickat: den 31 mars 2011 17:34
> > > Till: Johan Sandberg
> > > Kopia: mapproxy at lists.osgeo.org
> > > Ämne: Re: Response time question
> > >
> > > Hej Johan,
> > >
> > > On 31.03.2011, at 15:07, Johan Sandberg wrote:
> > >
> > > > hey!
> > > >
> > > > I'm measuring responses to Map Proxy when its seeded.
> > > > I dont get that satisfying response time as a wish. When I
> > > perform requests of a image size of 400*300, 10 request at
> > > the time I get low response time(around 50, 60ms).
> > > >
> > > > When I do image size of 800*600 the response time is up
> > to 1-2 sec.
> > > > And even bigger image size give response time up to 5-6 sec.
> > > > Is this normal response time when requesting seeded tiles?
> > >
> > > MapProxy should scale linear with the number of pixels. So
> > > you should expect 1/4 requests when changing from 400x300 to
> > > 800x600. You should measure the times with one concurrent
> > > requests at first and then you should look how you can scale
> > > that with increased concurrency, see below.
> > >
> > > > The request should be alligned with the resolution that is
> > > seeded so they don't have to re scaled.
> > > > How much is the normal cost in time of rescaling an image?
> > > Do the request have to be perfectly alligned with the cached
> > > resolution to achieve the low response time that I wish?
> > >
> > > Depends on the resampling method, you have to check for your
> > > self. The performance can degrade dramatically when you
> > > request a lower resolution than your first/upper level,
> > > because it then needs to merge lots of tiles. So make sure
> > > you don't run into that.
> > >
> > > > I have installed map proxy on a Linux computer with httpd
> > > apache server. I followed the wgsi example.
> > >
> > > You should run mod_wsgi with multiple daemon processes when
> > > you have more than one CPU:
> > > http://code.google.com/p/modwsgi/wiki/ConfigurationDirectives
> > >
> > > Regards,
> > > Oliver
> > >
> > > --
> > > Oliver Tonnhofer    | Omniscale GmbH & Co KG    |
> > http://omniscale.de
> > > http://mapproxy.org | https://bitbucket.org/olt | @oltonn
> > >
> > >
> > >
> > >
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> > > MapProxy at lists.osgeo.org
> > > http://lists.osgeo.org/mailman/listinfo/mapproxy
> > >
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