[mkgmap-dev] splitter questions

Thu Oct 22 10:36:46 BST 2020

Hi Gerd.

I managed to run the splitter and it completed well with
java -Xmx1800m  and setting the --max-nodes=1600000.
570 osm.pbf files were created.

For even larger maps
--max-nodes= higher should use less memory, but will those tiles be slower on 
a GPS unit and how much larger value is reasonable?

The main reason for creating such a large mapdata set is to make cross border 
routing to work.
Is there some other way i could produce the maps?
For example split and build map for each country separately (based on data 
from geofabrik) and then stitch the countries and routing data together, is 
this possible?

Regards
Karl.

On torsdag 22 oktober 2020 kl. 11:17:00 CEST Gerd Petermann wrote:
> Hi Karl,
> 
> the main purpose of --keep-complete is to have complete multipolygons in
> each tile to avoid empty parts of large lakes or flooded areas near large
> lakes. There is also an effect on routing regarding turn restrictions and
> route relations.
> 
> Anyhow, if you really want to produce a very large map on such a limited
> system you probably run into other problems when calculating the global
> index in mkgmap.
> 
> Gerd
> 
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von 7770
> <7770 at foskan.eu> Gesendet: Donnerstag, 22. Oktober 2020 10:59
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] splitter questions
> 
> Hi Gerd.
> Yes, it is 64-bit, but i don't have a lot of memory.
> --keep-complete=false, can it impact routing possibilities (routing may not
> work well) or is it mainly affecting how the map will look?
> 
> 
> Regards
> Karl
> 
> On torsdag 22 oktober 2020 kl. 10:49:23 CEST Gerd Petermann wrote:
> > Hi Karl,
> > 
> > if you are running a 64 Bit OS make sure to install a 64 Bit java runtime.
> > This allows to increase the -Xmx option. You probably need > 5G for this.
> > With a 32 Bit OS you can only try to disable the keep-complete option.
> > 
> > Gerd
> > 
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> > 7770 <7770 at foskan.eu> Gesendet: Donnerstag, 22. Oktober 2020 10:45
> > An: mkgmap-dev at lists.mkgmap.org.uk
> > Betreff: [mkgmap-dev] splitter questions
> > 
> > Hi.
> > 
> > I am trying to split data for some 15 countries. First step is to combine
> > the country data (with osmconvert) to one large o5m file and then try to
> > split the combined file.
> > The o5m file is about 14 GB in size.
> > 
> > When running splitter i give java -Xmx1600m
> > options to splitter are: --max-nodes=1500000 --no-trim
> > 
> > Splitter calculates around 640 areas/tiles to be created.
> > If i understand correctly, ways are parsed completely and then starts
> > relations.
> > 
> > After 100 000 relations i get:
> > ***** Full GC *****
> > and soon thereafter:
> > Exception in thread "main" Exception in thread "worker-0"
> > 
> >  java.lang.OutOfMemoryError: GC overhead limit exceeded... and many more
> > 
> > lines.
> > 
> > After this, one thread (out of two) dies but the other seems to hang doing
> > nothing... and i have to manually kill it later.
> > 
> > 
> > 
> > Now, i can give java a little bit more memory to java, say up to 1800m.
> > 
> > setting  --max-nodes= larger should use less memory says documentation.
> > With a larger max-nodes, will those tiles be faster or slower to display
> > on
> > a GPS unit?
> > What is a reasonable value, 10 000 000 nodes or 2 000 000?
> > 
> > 
> > Would --max-areas help my situation?
> > If i use --max-areas=350 (approx half of total expected tiles), based on
> > your experience would it be enough, or shall i better try with a value of
> > 220 (~1/3 of the total tiles)?
> > 
> > Regards
> > Karl
> > 
> > 
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