As far as I know, Tilemill is using mapnik which is querying postgres. Plain vanilla Mapnik is not doing more than one postgres query at a time (not multithreading queries). A patch made by mappy allows mapnik to multithread its pg queries. Are you using the exact same version of Mapnik as before ?
2013/8/25 Steve Bennett <stevag...@gmail.com> > Hi all, > > I'm running TileMill on an 8 core Ubuntu VM with 32GB of memory, on an > OpenStack cloud. Recently, my VM was destroyed, and I rebuilt it > (identically, I thought) on slightly different hardware (same cloud, but > different physical infrastructure). > > The new build is much slower at rendering - a screen worth of tiles at > zoom 13 can take around a minute. That is, with virtually the same setup, > same data, same styles. You can see some slow tiles here: > > http://emscycletours.site44.com/mel.html > > While panning around, the 'top' command shows mostly Postgres processes > (different from last time I had performance problems[1], when the > bottleneck was in Mapnik). Total CPU usage hangs around 12%: ie, exactly 1 > out of 8 cores is being used. > > > https://dl.dropboxusercontent.com/u/767553/GIS/Screen%20shot%202013-08-25%20at%2011.15.01%20AM.png > > top - 11:10:32 up 3 days, 36 min, 1 user, load average: 0.06, 0.17, 0.22 > Tasks: 133 total, 4 running, 129 sleeping, 0 stopped, 0 zombie > %Cpu(s): 11.5 us, 0.1 sy, 0.0 ni, 88.4 id, 0.0 wa, 0.0 hi, 0.0 si, > 0.0 st > KiB Mem: 32950396 total, 7150132 used, 25800264 free, 117864 buffers > KiB Swap: 0 total, 0 used, 0 free, 5221356 cached > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 2353 postgres 20 0 8510m 640m 635m S 41.2 2.0 23:36.57 postgres > 2354 postgres 20 0 8510m 644m 639m S 40.2 2.0 23:24.26 postgres > 2350 postgres 20 0 8510m 642m 638m S 14.0 2.0 23:19.19 postgres > 2375 postgres 20 0 8510m 643m 639m S 14.0 2.0 23:17.80 postgres > 13102 postgres 20 0 8508m 531m 527m S 13.6 1.7 13:03.21 postgres > 2355 postgres 20 0 8508m 531m 526m S 13.3 1.7 13:45.15 postgres > 2352 postgres 20 0 8510m 640m 636m S 10.0 2.0 23:31.17 postgres > 2348 postgres 20 0 8510m 644m 639m S 9.3 2.0 23:41.88 postgres > 12420 mapbox 20 0 3818m 1.0g 755m S 9.3 3.2 36:48.39 nodejs > 2357 postgres 20 0 8508m 530m 526m S 7.3 1.7 13:38.57 postgres > 2356 postgres 20 0 8508m 531m 526m R 6.3 1.7 13:42.52 postgres > 2376 postgres 20 0 8508m 531m 527m S 6.0 1.7 13:35.51 postgres > 13195 postgres 20 0 8508m 531m 527m S 5.3 1.7 12:33.65 postgres > 3027 postgres 20 0 8508m 531m 527m R 3.3 1.7 13:29.06 postgres > 2349 postgres 20 0 8508m 530m 526m S 3.0 1.6 13:38.19 postgres > 2358 postgres 20 0 8508m 531m 527m S 3.0 1.7 13:44.59 postgres > 26 root 20 0 0 0 0 S 0.3 0.0 0:08.64 ksoftirqd/5 > 2335 postgres 20 0 8489m 2732 1340 S 0.3 0.0 1:00.48 postgres > > So, wondering if anyone has any suggestions what the problem is, or how to > fix it? Why is Postgres apparently using only one core, even though it has > many processes? What tools could I use to further diagnose? > > My changed Postgres settings are as follows: > > shared_buffers = 8GB > autovacuum = on > effective_cache_size = 8GB > work_mem = 128MB > maintenance_work_mem = 64MB > wal_buffers = 1MB > checkpoint_segments = 10 > > The server is set up as described here: > http://steveko.wordpress.com/2013/05/08/tilemill-server/ > > I'm not yet using any tile cache. I will do that next, but the problem I'm > trying to solve at the moment is very slow tile generation, not slow > serving of rendered tiles. > > Many thanks in advance, > Steve > > > [1] > http://gis.19327.n5.nabble.com/TileMill-performance-td5751158.html > > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk > > -- Christian Quest - OpenStreetMap France Un nouveau serveur pour OSM... http://donate.osm.org/server2013/
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