[Discuss-gnuradio] Message passing - issue with messages left in queues after running top block

[Perper]

Hi all,

I've noticed that "Run to completion" works now in situation when
message passing is used, which is great!
I have a related question. I'm creating a block which uses message
passing, and run it once:

        tb = some_block(fname="file1")
        tb.start()
        tb.wait()

#at this moment tb has still some unprocessed messages in message queues
#so if I run the block again on another file ...

        tb.set_fname("file2")
        tb.start()
        tb.wait()


I can see messages that were result of processing of file1. Do you know
how to avoid this?
One of acceptable solutions can be flushing msg queues after processing
of file1, but I don't know how to achieve this.

Best Regards,
Piotr Krysik