Don't stop if pushbuffer is finished

[JayFoxRox]

The original design assumed that pushbuffers would eventually finish. However, in reality, the pushbuffers typically never stop running, as there's always new data queued already.
I then decided to implement continous tracing (which is also more useful), but the old stop logic remains.

I'm not sure which changes would be necessary to detect a restart.
I worry that this might break our current tracing logic. Also see #7