Internal error: 745 shards not a power of 2

[victoraalvarez]

When trying to convert my GeoJSONs to tiles, I get the error Internal error: 745 shards not a power of 2.

Merging string pool
Merging vertices
Read 0.01 million features
Reordering geometry: 25%
Reordering geometry: 79%
19080 features, 555606 bytes of geometry and attributes, 19945 bytes of string pool, 0 bytes of vertices, 0 bytes of nodes
Internal error: 745 shards not a power of 2

My tiles end up empty at only 28kb. I'm using Tippecanoe with Ubuntu on Docker. I haven't gotten this issue before but it's suddenly coming up even though nothing has changed with my installation. I'm calling Tippecanoe from Python subprocess using the command below:

subprocess.run(['tippecanoe',
                '-Z', str(zoom_range[0]),
                '-z', str(zoom_range[1]),
                '-B' + str(zoom_range[0]),
                '-as',
                '-ad',
                '-an',
                '-ac',
                '-pi',
                '-aN',
                '-aD',
                '-aS',
                '-ao',
                '-S', str(tile_simplification),
                '--drop-polygons',
                '--force',
                '-o',vector_tile, 
                vector_file])

Not sure where to go from here and there doesn't seem to be much online about this issue, any tips on debugging?

[e-n-f]

Thanks for the report! I'm not sure exactly why this is happening but some extra information would help. Would you mind building tippecanoe from #220, rerunning your tiling, and sending me the extra log output that you get? On my laptop I get:

Using 32 temporary files and 1 threads on 8 CPUS for 32 child shards
Using 32 temporary files and 4 threads on 8 CPUS for 8 child shards
Using 32 temporary files and 8 threads on 8 CPUS for 4 child shards
Using 32 temporary files and 8 threads on 8 CPUS for 4 child shards
Using 32 temporary files and 8 threads on 8 CPUS for 4 child shards
Using 32 temporary files and 8 threads on 8 CPUS for 4 child shards

but there must be a miscalculation somewhere based on how many CPUs your computer has and how many files it allows open at once.

[victoraalvarez]

Thanks for your reply! Unfortunately, I wasn't able to build it successfully and ran into a couple of errors in the process. However, for context, Tippecanoe is running on a Kubernetes node which means it has access to shared CPU which is quite large. With the way Kubernetes works, I don't think the size of the CPU is also going to be guaranteed a power of 2 which would explain the error. I'll keep trying to build it and comment again if I can get that extra logging.

[simon28li]

Hi, is there any progress on this issue? I've had this problem, but it's not on every machine. Is it caused by environmental issues?

[victoraalvarez]

Same, it was only occurring on certain machines in a Kubernetes cluster so we just ended up using it on the ones that worked. I imagine it has to do with the underlying CPU.