[mkgmap-dev] mkgmap heap space errors and overlap in splitter

Tue Jul 24 20:16:54 BST 2012

Hi mappers,

for a couple of days now I am struggling with the combination
of the --overlap value in splitter, holes at tile-borders (woods etc.)
and mkgmap heap space out
of memory errors. I am trying to process france.

I have learned that without setting any --overlap value (thus default)
I need little more than 1000M to process france in mkgmap.
But this gives me a lot of faulty tiles.
Those tiles usually miss "color" where e.g. wood should be.
I suspect this to be all large multipolygons, mostly wood areas.

Increasing overlap-values in splitter helped me for other countries.
But as soon as I increase the --overlap value to e.g. 3000,
memory needs in mkgmap go up quickly causing heap space errors.
For many countries like germany, overlap=10000 worked fine with no
tile errors and no memory problems, although memory needs are quite high.

Just for france, even XMX8000M does not work,
there seems to be no limit that works.
Values for max-nodes (usually 200) and max-area (usually 600000)
does not seem to have any influence on this.
I am never experiencing memory issues in splitter, just mkgmap.

Any ideas anyone what stupid error I may be doing?
Are any other parameters in splitter or mkgmap relevant
for decreasing heap space?

Thank your for hints how to deal whith this.
Michael