[GRASS-dev] Using GRASS in long running and multithreaded applications Was: Re: The tomcat shut down ...

Hamish hamish_b at yahoo.com
Sat Sep 26 01:55:08 EDT 2009

Glynn wrote:
> The main issue for concurrent reading is that the raster
> library caches the current row, so that upscaling doesn't
> read and decode each row multiple times. That's problematic
> if you want multiple threads reading the same map.

to me multi-threaded multi-map read does not seem so exciting.
typically both maps are in the same GISDBASE, so on the part of
the same disk drive, which can only physically read one thing
at a time, and asking the drive to jump around non-sequentially
to read two maps at once would just slow the overall read down.
I've got nothing against making the libs thread-safe, but
personally I'm much more intersted in preping the processor-bound
modules for multi-threading as I see more gains there vs a
slight speedup in I/O-bound libs.

but then I'm not trying to keep the libs running long term :)
and don't know how the vector cleaning tasks fit into this.



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