Hi WanMil,
Compared to v3 (posted by Carlos in thread "Wrong multipolygon warnings") some unused debug messages have been removed.
The patch enables the multipolygon code to process multipolygons with overlapping lines.
For the Geofabrik Finland extract of today, the patch reduces the amount of log output from 198129 to 195563 bytes. If I specify --generate-sea=multipolygon I will get 1887595 bytes of log, including 3814 warnings 'is not processed due to an unknown reason'. Normally, I get only one 'unknown reason' warning, for a monster multipolygon that I created some days ago: http://www.openstreetmap.org/browse/relation/404644 WanMil, can you please take a look at that multipolygon and improve the code or diagnostics? That multipolygon could be easily split near Ihanteensalo, but I will leave it as is for now, so that the problem can be diagnosed. Marko