[OSM-dev] How is Mapnik Performances ?

[Roberto Navoni]

Jon Burgess ha scritto:
> On Tue, 2009-01-06 at 00:58 +0000, Roberto Navoni wrote:
>   
>> Jon Burgess ha scritto:
>>     
>>> On Mon, 2009-01-05 at 20:46 +0000, Roberto Navoni wrote:
>>>   
>>>       
>>>> Hi,
>>>> I have a question for OSM-Developer ;)
>>>> So I'm trying mapnik for render italian OSM planet , but the performance 
>>>> on my sandbox is not so god . I'm using an old one hp laptop that use 
>>>> Ubuntu 8.04 as SO and as hardware use P4 3 Ghz 1 GByte of ram . I see 
>>>> that actualy are rendering only two  tile for second.  I'm usining 
>>>> postgress 8.3 as db. Are there some optimization for speed up the render 
>>>> time.
>>>> How many mapnik i can start on a single cpu ? The performance is better ?
>>>>     
>>>>         
>>> Are you using generate_tiles.py for rendering your tiles?
>>>   
>>>       
>> Yes I use generate tiles
>>     
>>> Is the web server under your control or are you serving static files via
>>> a 3rd party web host?
>>>
>>>   
>>>       
>> I'm doing some test on my server ... I have complete control on it , I'm 
>> using Ubuntu 8.04 as Operating systems ..
>>     
>>> The main tile.openstreetmap.org server uses mod_tile[1] which uses
>>> several optimisation tricks to improve the performance but you can only
>>> get the full benefit of this if you can install a custom Apache module.
>>>
>>>   
>>>       
>> Ok ... now  I try It.
>>     
>>> - multithreaded rendering (should exploit improve efficiency if you have
>>> hyperthreading in your CPU).
>>> - rendering and storing tiles in "meta-tiles" (8x8 at once).
>>> - rendering on-demand, avoiding the need to pre-render lots of tiles
>>>
>>> If you can't install the Apache module then the mod_tile render daemon
>>> can be used standalone with the speedtest & convert_meta tools to
>>> generate a tree containing plain PNG files for uploading to a 3rd party
>>> web host. I can provide more details if you are interested in this.
>>>
>>> Last time I benchmarked the tile.openstreetmap.org server it was
>>> rendering approximately 600 tiles/s using 2 x dual core Opteron CPUs.
>>>   
>>>       
>>> The osm.xml file has got significantly more complex since I did those
>>> tests so the numbers are probably a bit slower now. Even so, your P4
>>> should manage more than 10 times your current performance.
>>>
>>>   
>>>       
>> Strange .. is possible that there're some problem on db configuration ?
>>     
>
> Possibly but postgres is not normally the bottleneck.
>
>   
>>  
>> With top I see the cpu usage by thread and i see that postgress using 15 
>> % of cpu and mapnik use only 12% of cpu ... is possible that there're 
>> some setting to change on postgress or on mapnik ?
>>     
>
> Some CPU is taken by the "convert" step. Since this is a short lived
> process it does generally appear in top.
>
> If you want to test, simply comment out the following lines in
> generate_tiles.py and see how much faster it goes:
>
>     command = "convert  -colors 255 %s %s" % (tile_uri,tile_uri)
>     call(command, shell=True)
>
> For serving tiles you really want to use 256 colours since the tiles are
> much smaller. If you are using a recent build of Mapnik then this
> includes a faster colour conversion algorithm, just change the format
> from png to png256 a line earlier:
>
>     view.save(tile_uri,'png256')
>
> Jon
>
>   
Thank for your reply I see that convert use cpu with top for some times 
... now I try do you know how i can update Mapnik 4.0 to the new one ?
Best Regards
Roberto
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