[mapserver-users] high memory usage on map draw

[Stephen Woodbridge]

On 11/29/2011 10:02 AM, Daniele Debernardi wrote:
> The solution is not pumping up the memory limit of the server, because
> if i get 2 request at the same time
> I still have memory problem.

It sounds like you have not adequately sized the server for the tasks 
you are asking it to perform. Mapserver is designed for performance so 
that it can handle requests quickly and free up the memory it is using 
for the next request. If you start swapping or paging data to disk that 
slows down all processes and can overwhelm the system with too many slow 
requests that are all consuming memory and not exiting as fast as new 
requests are coming in.

If you are making an enhancement request for say making mapserver use 
less memory and temporary disk files or swap space at the cost of 
performance, then you should add a ticket to the tracking system. This 
is not a short term solution.

> Which is the best way (output format) to generate high resolution map
> images with full symbology support?

I defer to Thomas on this one. But he has already mentioned that 
probably doing something like direct pdf output and converting any 
pixmap symbols into scalable symbols is the best way to go.

-Steve W

> Il 29.11.2011 15:49, Stephen Woodbridge ha scritto:
>> On 11/29/2011 3:20 AM, Daniele Debernardi wrote:
>>> Hi,
>>> with mapserver trunk version (but i think with others too) I have to
>>> generate very big map to be imported in a pdf file.
>>> I use php mapscript to generate maps with 300 dpi for an A1/A0 pdf page
>>> or bigger.
>>> This mean that the map has dimensions like 15000x25000 pxl and when I
>>> call the MapObj->draw method i get this error:
>>>
>>> PHP Warning: mapObj::draw(): [MapServer Error]: agg2CreateImage():
>>> mapagg.cpp: 708: Out of memory allocating 1550851152 bytes.
>>>
>>> Map server is configured with the AGG/PNG driver with imagemode RGBA.
>>>
>>> Is it normal that need so much memory to generate the image?
>>
>> Just for the image buffer you need 15000x25000x4 pixels = 1500,000,000
>> and AGG might actually allocate a slight larger image buffer so it
>> does not create edge effects while antialiasing objects close to the
>> edges. So the above request does not seem unreasonable.
>>
>>> I already tryied the php ini_set memory_limit but with a limit of 2048M
>>> i still have some problem with memory.
>>
>> Try setting the limit a little higher like to 2564-3072M can see if
>> your memory problems go away. Of course this assumes you have a system
>> with a lot of memory.
>>
>> -Steve W
>>
>>> I checked other possible outputs but generating maps in pdf through
>>> Cairo driver but doc says that polygons filled with symbols are not
>>> supported, and for that reason I cant use it.
>>> SVG output has some limitations too like line drawn without symbols or
>>> pixmap symbols not supported.
>>>
>>> Is there a better way to generate so big map images and imported in a
>>> pdf file?
>>>
>>> Hope you guys can help me.
>>>
>>> Daniele
>>> _______________________________________________
>>> mapserver-users mailing list
>>> mapserver-users at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>>
>> _______________________________________________
>> mapserver-users mailing list
>> mapserver-users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>