[mkgmap-dev] Possible memory reduction in mkgmap

Wed Jan 9 12:07:16 GMT 2013

Hi,

it is easy to change the HashMap<Long,Coord> coordMap in  ElementSaver 
to use the OSMId2ObjectMap that I've implemented for splitter.
This could reduce peak memory usage in mkgmap.

A few numbers according to VisualVM:
2.248.404  coord instances managed in the HashMap  req. 186.447.135 bytes,
with OSMId2ObjectMap it is 57.194.684.
This doesn't include the memory that is needed to store the Coord instances
itself,
(which I think is 2.248.404 * 32 = 71.948.928 bytes) 
it is just the overhead for the map. 

The disadvantage: OSMId2ObjectMap uses fastutil.jar, which is not used in
mkgmap 
until now. I could try to change OSMId2ObjectMap so that it runs without
fastutil.jar,
but that would mean to invent the wheel again.

Comments?

Gerd

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