Re: [Discuss-gnuradio] Freeze when writing to linux fifo pipe

[Eric Blossom]

On Tue, Apr 20, 2010 at 02:57:04PM +0200, Joachim Roop wrote:
> Hi,
> I am trying to write to a linux pipe/fifo, but sadly this seems to freeze 
> python. I am using Ubuntu 10.04 and gnuradio 3.2.2.dfsg-1ubuntu1.
> Please try to execute the code and tell me why this makes the app pause.

 $ man 3 mkfifo

Opening a fifo for reading blocks until there is a writer and vice versa...

Eric



> 
> #! /usr/bin/python
> 
> # Import stuff
> from gnuradio import gr, gru, eng_notation, optfir
> from gnuradio.eng_option import eng_option
> from gnuradio.wxgui import slider, powermate
> from gnuradio.wxgui import stdgui2, fftsink2, form, scopesink2
> import sys
> import os
> 
> # Main application
> class main_app (stdgui2.std_top_block):
>       def __init__(self,frame,panel,vbox,argv):
>               stdgui2.std_top_block.__init__ (self,frame,panel,vbox,argv)
> 
>               print '!!!Cleanup'
>               os.spawnlp(os.P_WAIT, 'rm', 'rm','/tmp/gnutest1.raw')
>               os.spawnlp(os.P_WAIT, 'rm', 'rm','/tmp/gnutest2.raw')
>               print '!!!make a fifo'
>               os.spawnlp(os.P_WAIT, 'mkfifo', 'mkfifo','/tmp/gnutest1.raw')
>               print '!!!make file sink without the fifo'
>               outok = gr.file_sink(gr.sizeof_short,'/tmp/gnutest2.raw')
>               print '!!!make file sink with the fifo (FREEZING)'
>               outcrash = gr.file_sink(gr.sizeof_short, '/tmp/gnutest1.raw')
>               print '!!!everything went better than expected'
> 
> if __name__ == '__main__':
>     app = stdgui2.stdapp (main_app, "crashtest")
>     app.MainLoop ()