On 04/14/2011 11:29 AM, Svavar Kjarrval wrote: > Why is the queue not enhanced to avoid instances where tile-rendering > queries are rejected due to a full queue?
I have no knowledge about the specifics of this server, but I can speak generically: Requests are coming in faster than the server can process them. This means that some requests have to be dropped, no matter what*. Once you know that, the length of the queue doesn't matter much. The advantage of a shorter queue is that it reduces latency. Since each request has to wait for everything in front of it to be processed, the fewer things in front of the one you care about, the faster it'll happen. The advantage of a longer queue is that it can smooth out any variations in request speed. If sometimes requests come in faster than the server can process, and sometimes they come in slower, then requests can build up in the fast times and the server can catch up when they slow. This is apparently what happens to OSM between 00:00 and 06:00 on the graph. By lengthening the queue, it would be possible to make the server be constantly busy during that period as well. However, it would come at the expense of increased latency, and depending on how many requests are being dropped, filling in that period of lesser activity might not make much of a difference. * Technically, you could let the queue will grow indefinitely and time to process any given request will approach infinity. That's not a good idea though. _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
