[Discuss-gnuradio] stream_to_vector input data size and lock/unlock

[Kieran Brownlees]

Hello all,

I have some interesting behaviour using a stream_to_vector with a large number of inputs items (12800). 

The standard method of top_block.connect(), top_block.start() works fine but when I try and perform the same operation after a top block has already been started I get a sched error.

Sample test case:

import time
from gnuradio import gr

class top_block (gr.top_block):
    def __init__(self):
        gr.top_block.__init__(self)
        s2v = gr.stream_to_vector(gr.sizeof_gr_complex, 12800)
        ns = gr.null_source(8)
        self.connect(ns, gr.null_sink(8))
        self.start()
        self.lock()
        self.connect(ns, s2v, gr.null_sink(102400))
        self.unlock()
        
if __name__ == '__main__':
    app = top_block()
    print "End"

If the above python script is run as it is I get this on my 3.1.3 installation:

address@hidden:~/test$ python s2vtest.py

sched: <gr_block stream_to_vector (1)> is requesting more input data
  than we can provide.
  ninput_items_required = 12800
  max_possible_items_available = 4095
  If this is a filter, consider reducing the number of taps.
End
address@hidden:~/test$

If however you move the self.start() in the above script below the second self.connect and remove the lock() / unlock() then it runs fine (and works perfectly). I was just wondering if anyone can explain this behaviour to me?

Interestingly on my 3.2 install the max_possible_items_available is 8191.

Thank you,
Kieran