Do not wait for process to complete if --duration is specified

[orlp]

It appears (at least on Mac, perhaps this is a bug?) that samply waits for the recorded program to complete before writing out the profile.json or opening the profile page, even if --duration is specified. This is especially annoying when wanting to use the profiler to debug programs that are non-responsive.

Please write out the profile.json data and open the profiler interface immediately when the recorded duration has expired and/or provide an option to kill the child process when the duration has expired.

[mstange]

I agree this would be preferable.