[mapserver-users] Out-of-memory error due to huge NTv2 shift-file

[Sven Schroeter]

Hello, Michael,

interesting, I have already experimented with the new NTv2 grid for Mannheim and we also use Mapserver + Postgis. 
I didn't have the problem you mentioned, but the test system wasn't in production yet. We transform the data directly and not on-the-fly. Unfortunately, I do not have a solution to the problem you have found, but I would be very interested in it.

Greetings
Sven


Von: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] Im Auftrag von Michael Schulz
Gesendet: Mittwoch, 24. Januar 2018 15:47
An: mapserver-users at lists.osgeo.org
Betreff: [mapserver-users] Out-of-memory error due to huge NTv2 shift-file

Dear mapservers, 

in our region in Germany a new CRS is introduced (ETRS:25832). For cadastral precision a NTv2 grid-shift file has been generated. This uses a very fine grid and is now 350MB in size. While we tested this file in our dev environment and everything worked fine, our production environment is not able to cope with the amount of requests, since it seems, that each mapserver process is opening that file and soon Out-of-memory errors appear, until the server is not answering anymore. Not sure whether each request is causing the .gsb file to be loaded, or only requests that actually invoke a reprojection.

I assume that we can reduce the amount of needed reprojections as soon as data is permanently projected to the new CRS, but still some on-the-fly projections will be necessary. I am looking for good strategies to handle this problem. Could anyone give some advice? 


Cheers, Michael

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Michael Schulz
Kandelstr. 22