[mkgmap-dev] [PATCH v1] Experimental support for multi-threading

Mon May 11 10:15:06 BST 2009

Hi Johann,

> > As a lot of the processing has to be done in sequence, the
> > opportunities for using multiple threads are somewhat limited.
> > However, the attached patch parallelises:
> >
> > 1 - processing of ways from OSM form to MapLine/MapRoad.
> >
> > 2 - processing of cities
> >
> > 3 - processing of POIs
> >
> > 4 - processing of polylines and polyshapes within each division
> >   
> >
> In this situation (a lot of sequential processing), wouldn't it be an 
> better approach to start several processes of mkgmap with different tiles?
> 
> This could be fully parallelized without dependencies.
> 
> Afterwards the different tiles had to be merged into an single img file. 
> This process could be started in another extra process with the 
> finishing of the first tile.

That's fine as long as you have the memory available and are processing
more than one tile.

I wrote the patch as I was intrigued as to how much performance gain
could be achieved using multi-threading. It's not a stunning improvement
but certainly good enough to consider doing more work on it.

Cheers,

Mark