How long is a piece of string?
There are many (potentially) limiting factors. Memory size, ulimit values, system
hard limits in respect to numbers of processes, CPU usage, memory usage, ...
The most sensible approach for you would have to be to just go and try, and see
what happens. That's about all I (or anyone else who doesn't have all the details
of your application and/or environment) can suggest. With your input not even a
very general hand-waving is going to be possible.