Parallelizing calls to msDrawLayer()

Frank Warmerdam warmerdam at POBOX.COM
Sat Oct 13 20:38:12 EDT 2007

Paul Spencer wrote:
> David,
> While you can perhaps gain some performance in a single map draw, in 
> most real life uses of mapserver, folks are either serving many 
> simultaneous requests or generating tiles in some way.  I think in 
> either case, the addition of multi-threaded layer draws will actually 
> cause contention for processor time with the multiple processes that are 
> serving the requests and could hurt overall performance in high load 
> systems.
> I think that you could probably get more bang for your development bucks 
> by investing time in profiling the existing code.


I quite agree with Paul on this.  David is welcome to examine multi-threaded
rendering if he wishes of course, but I am hesitant about incorporating back
such changes given the inherent complexity and riskiness.   As Paul points
out "overall throughput" for heavily used sites will not benefit from such
changes and might even suffer.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at
light and sound - activate the windows |
and watch the world go round - Rush    | President OSGeo,

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