[mkgmap-dev] Out of heap space: Too many tags?

Tue Feb 24 22:50:07 GMT 2009

On Tue, Feb 24, 2009 at 10:17:47PM +0100, Wolfgang v. Hansen wrote:
> I just tried to compile a relatively small tile and got an out of memory  
> error from Java! Normally when the tiles get too large, there are error  
> messages from mkgmap. So I investigated a little bit and found out that  
> the tile in question contained a huge number of <tag>s. The number of 
> tags is ten times the number of nodes in the file.

The typical ratio in the UK seems to be about the same number or slightly 
more tags as nodes.  So ten times is a lot.  In places where there
have been data imports it is probably more normal to have large numbers
of tags though.

Normally the number of nodes determines the amount of memory needed, but
if there are so many more tags then they will indeed require even more
memory.

If there are tags on each node that will also bloat the memory required
dramatically too.

..Steve