[Discuss-gnuradio] Debugging ControlPort/Thrift problem (Re: costas ambiguity and correlate-and-sync block in qpsk)

[Andy Walls]

Hi Arik:

First off, try the attached Rx_syncd_3.grc.  I disabled the modulate
vector block and hard-coded in a vector of 150 preamble samples.

On Sat, 2016-04-02 at 20:11 -0400, Andy Walls wrote:
> Hi Arik:
> 
> On Sat, Apr 2, 2016 at 7:41 PM, Landsman, Arik
> <address@hidden> wrote:
>         Hi Andy,
>         
>         Still looking it over, but one thing jumps out right away -
>         for some reason I couldn't execute either Rx_syncd_2.grc or
>         the Rx_syncd.py. getting the same error in both cases:
>         
>         ""
>         Generating:
>         '/home/ubuntu/Desktop/MSProject/alternateVersions/Rx_syncd_2.py'
>         
>         Executing: '/usr/bin/python2
>         -u /home/ubuntu/Desktop/MSProject/alternateVersions/Rx_syncd_2.py'
>         
>         Using Volk machine: sse4_1_64
>         Thrift: Sat Apr  2 19:05:54 2016 TServerSocket::listen() BIND
>         9090
>         terminate called after throwing an instance of
>         'apache::thrift::transport::TTransportException'
>           what():  Could not bind: Transport endpoint is not connected
>         ""
>         
>         does this look familiar by any chance?
> 
> 
> It looks like a GNURadio ControlPort / Apache Thrift error.
> 
> 
> I took your flowgraph and modified it slightly, only adding a few
> blocks:
> 
> -modulate_vector
> -skip_head
> -keep_1_in_n
> -qt_time_sink
> -feedforward_agc
> -multiply const
> -qt gui range
> 
> One of those might be doing it.  Disable skip_head, keep_1_in_n, and
> the constellation sink they connect to.  Hopefully it's one of them.
> 
> Otherwise, you didn't drop a control port related block on the
> flowgraph did you?


Here is some good info on how GRNURadio's control port works at a high
level:
https://gnuradio.org/redmine/projects/gnuradio/wiki/ControlPort
https://gnuradio.org/doc/doxygen/page_ctrlport.html

>From that second page, it appears that running two flowgraphs on the
same machine has a problem caused by Apache Thrift and GNURadio's
configuration of the Control Port network port (default of 9090).
https://gnuradio.org/doc/doxygen/page_ctrlport.html#ctrlport_thrift_issues

So please only run on flowgraph at a time, at first, to troubleshoot
this issue.

Second, you may want to try setting the GR_CONF_THRIFT_PORT environment
variable to something other than 9090, a port that you know is open on
your machine, for each separate flowgraph that you run.

FYI, the modulate_vector block runs a "mini"-flowgraph, before the main
flowgraph actually runs:

https://github.com/gnuradio/gnuradio/blob/master/gr-digital/lib/modulate_vector.cc#L59
 
Hopefully, there isn't some sort of weird race condition with the Thrift
port being open for the modulate_vector block's mini-flowgraph and the
main flowgraph. 


Hi Tom,

Do you have any comments or insights on Arik's Thrift error message
and/or the possibility of modulate_vector's mini-flowgraph causing
problems with Thrift's network port and the main flowgraph? 

Regards,
Andy

> Regards,
> 
> Andy

Rx_syncd_3.grc
Description: application/xml