[mkgmap-dev] tile takes very long time to generate

Mon Mar 8 06:31:44 GMT 2021

Hi Karl,

I don't think that the order of the tiles should make a big difference. It is quite normal that some tiles take longer than others, but 30 minutes is far too long.
One well known reason for slow processing are very complex multipolygons like Lake Huron. Another might be huge areas of sea. So, to find out if the order or the content is causing the delay you can process the tiles in a different order.
I often use VisualVM to monitor a running mkgmap, it helps to find out which routines are called most often.
If you identify a single tile that takes very long (also with the default style) you can upload that tile to http://files.mkgmap.org.uk/
Best is to add a small file with the options that were used, but you can also post them here.
Hope that helps.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von 7770 <7770 at foskan.eu>
Gesendet: Montag, 8. März 2021 06:53
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: [mkgmap-dev] tile takes very long time to generate

Hi.

I observe a situation that one of the very first tiles (often the first or the
third) that mkgmap generates takes 20 - 30 minutes to generate, wheres the
others take about 30 seconds each.

The map data produced by splitter is a total of around 700 files with splitter
option --max-nodes=1275000.

sea and bouds are used for mkgmap.

At first i thought i am running low on memory but changing to max-jobs=1
(instead of the possible max of 2) did not make any change.

Is mkgmap doing something specific in the beginning that can explain this long
time generating one of the very first tiles?

I can provide more details, let me know how i can best collect those details
in case i need to set some parameters to have mkgmap to say more about what it
is doing.

Regards
Karl

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