Multiprocessing

[lukasmartinelli]

In theory multiple processes can read from one readonly RocksDB. Dunno whether it would speed it up though.

[jenningsanderson]

I think this is a worthy feature -- add_tags could take a file argument with one feature per line and break it into chunks as tippecanoe does with -P

[jenningsanderson]

Bumping this issue with reference to: #16

Sounds like we've got ways to build the INDEX in < 10 hours -- more over, we're close to being able to create persistent, shareable indexes that are updatable with a PBF file....

Next question is getting the data back out of rocksdb and ready for tiling; since input is line delimited, let's try to cut into chunks and parallelize?