On Mon, 2008-06-09 at 18:48 +1000, Brett Henderson wrote: > Tom Hughes wrote: > > I may be being dense here, but this is openstreetmap-talk (not > > even dev) not tilecache-talk... Is there not somewhere better you > > should be going to with this where there will be experts in tilecache > > that can help you? > > > I've sent an email to the tilecache mailing list, just thought there > might be some folks around here familiar with this stuff. As for > osm-dev versus osm-talk, I wasn't sure which was appropriate in this > case ... > > > > Well the obvious answer is that something in your apache configuration > > is limiting the amount of memory that the daemons can use. > > > Sounds reasonable, I'm not too familiar with the innards of apache. > It's a default fedora 8 install, I'll poke around and see what I can find. > > Unless of course you really are managing to exhaust your physical > > memory and swap - how big do your apache processes get? > The machine has 2GB of RAM and isn't overly stressed. The processes are all > using around 115MB virtual memory, 24MB resident memory and 13MB shared > memory.
My previous experience with tilecache suggested that it did not have any mechanisms to limit the number of tiles that could be rendered concurrently which could lead to lots of processes trying to render at once. The recent Mapnik builds try to mmap() the shapefiles while rendering[1]. Since the largest shapefile is a few hundred MB this could easily cause some issues if the file was mmap'd multiple times in a single process. This might be a particular problem if you use a 32-bit system in the multi-threaded Apache worker mode. Perhaps you should try drastically cutting down the number of Apache server processes and see if this resolves the issue. Alternatively you might want to look at mod_tile[2]. One of its design goals was to achieve a well defined behaviour under load. It runs well on the main tile.openstreetmap.org server. [1] http://trac.mapnik.org/changeset/628 [2] http://wiki.openstreetmap.org/index.php/Mod_tile Jon _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
