Thanks for the suggestions, Rob. This definitely sounds like it would be worth investigating. The only problem I can forsee with this is that the current Mapnik build for Windows doesn't work with the latest Python. At least it didn't last time I tried!
/W From: Robert Coup [mailto:[email protected]] Sent: 07 September 2009 00:26 To: Warren Vick Cc: Jon Burgess; [email protected] Subject: Re: [Mapnik-users] Multi Threading On Mon, Sep 7, 2009 at 2:10 AM, Warren Vick <[email protected]<mailto:[email protected]>> wrote: Interesting... a drop from 35 to 23 seconds seems quite poor so I wonder if there is no concurrency occurring at all, just perhaps a better "packing" of the execution. Alternatively, perhaps the cost of running the threads is quite high. With just two tile render jobs, I doubt if there is an I/O bottleneck. I had a recent experience with running two separate processes (on a quad core machine) which take about an hour each, is that the execution time is still about the same. i.e. almost perfect parallelism. I'll report the results of my own thread vs. process tests in the next day or two. You could also compare it to the python multiprocessing module (native in Python 2.6+, or available from PyPi for 2.4/2.5). It's interface is virtually the same as the threading module, but it uses separate processes. Rob :)
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