[OSM-dev] Performance

Nigel Magnay nigel.magnay at gmail.com
Wed Jul 12 11:45:36 BST 2006


I've been idly playing around with some datasets from the april
planet.osm, and I'm wondering as to where (and if) there's performance
bottlenecks.

I first stumbled across OSM last week and thought "this is *way*
cool". So I downloaded JOSM, and plugged some coordinates in
(bbox=-1.40625,51.630859375,-1.0546875,51.796875 for these examples)

Given that area, it seems to take JOSM about 45-odd seconds on my
machine to display, of which 25 seconds seems to be waiting for a
response.

However, a straight api call of
/map?bbox=-1.40625,51.630859375,-1.0546875,51.796875 seems to take
about 12 seconds. It's got a fair amount of work to do and I do note
the status page mentions database performance issues.

Thinking that it was query-bound, I hacked a quick java equivalent of
the API, ran the same queries (though I had to substitute
current_nodes for nodes, etc), and found I could return equivalent xml
from my creaky old local machine as XML in about 5-6 seconds (5558
nodes, 6154 segments, 238 Ways)

Is ruby particularly slow at the rowset->xml generation phase? Is JOSM
doing more work than a simple map call ?




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