GnuRadio flowgraphs in workerthread

Hello guys,

would it affect the performance of my GNURadio-programm negatively if I
tried to run my GNURadio flowgraphs in a workerthread instead of the
mainthread. In the mainthread I would like to implement a custom

Also, I still do not understand what the happens when I call wait()
stop(). I have two flowgraphs, one for receiving and one for
with the USRP2. Both use a gr.head block and run to completion after
have proccessed a certain ammount of samples. I did some testing and it
seems to work fine. But still I would like to know if the following
lines of
Code make any sense:


receiver = receiver_class()

transmitter = transmitter_class()

______# reset the head blocks and some other stuff:

Can I use run() OR should I use start() + wait() OR start(), wait() +

Alex Peterson

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Wow, thank you for your detailed answer.

But one thing I don’t understand:

" If you called run() on the first one, it would not
return from that call until the flowgraph exited, and your second
flowgraph would get started too late. "

I don’t want the flowgraphs to run parallel to each other. One flowgraph
senses the spectrum with the USRP and the second flowgraph transmitts a
signal with the same USRP (depending on the measurements of the
So it’s important that they run consecutively.

In this case, is it fine the way I do call run() for both flowgraphs?
replacing it with start() + wait() make any difference?

Also, I hope you don’t mind if I add one more questions:

When the flowgraph is stopped by a head-block the threads are shutdown,
the flowgraph itself still exists with all the blockinternal member
variables (including possible changes during the first run) and after a
head-reset it can be re-run with the run()-method. This re-run starts
the previous run stopped. Is that correct?

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