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[mkgmap-dev] splitter - performance and memory

From Steve Ratcliffe steve at parabola.me.uk on Tue Jul 21 15:03:29 BST 2009

On 19/07/09 23:58, Chris Miller wrote:
> Good news - with my changes the areas.list file was generated fine, peaking at maybe a 3GB heap.


It is also worth noting something that osmcut (an other map splitter) 
does. It has two modes; one where a map is used for when the input file 
is small and another where a list is used and the node-id is the index 
into the list. The later is used for splitting the whole planet file.

The second method uses less memory where the memory wasted by node-ids
that are not in use is less than the amount of memory used by storing
the node-id plus the memory wasted in free space in the hash maps.
As currently most nodes are used (about 88%) this is a big win
on the whole planet file, while still giving access to the node ids.

I've committed the patch.


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