Allow more than 32 generalization jobs

[Paul Norman]

osm2pgsql-gen currently is limited to 32 threads.

osm2pgsql/src/gen/osm2pgsql-gen.cpp

Lines 754 to 757 in 374eca4

 if (jobs < 1 || jobs > 32) { 
     log_error("The --jobs/-j parameter must be between 1 and 32."); 
     return 2; 
 } 

This is limiting me to using less than 50% of my CPU.

Is there any hard limit elsewhere in the code that prevents the upper limit from being removed?

[Jochen Topf]

I took that limit from the --number-processes parameter. But that is a bit different than the number of jobs here. So I don't have anything against making the limit larger. I think we should have some limit, to save the user from themselves doing something ridiculous here. And the question is at which point more threads will not make this faster.

[Paul Norman]

Tile based CPU bound work like this will generally parallelize until the CPU is saturated, with as many threads as there are hardware threads. The OSMF render servers have 112 threads, and they're moderate as servers go.