# Messages getting dropped

**URL:** <https://www.ruby-forum.com/t/messages-getting-dropped/232907>\
**Category:** GNU Radio\
**Created:** [November 4, 2014, 9:45am UTC](https://www.ruby-forum.com/t/messages-getting-dropped/232907 "2014-11-04T09:45:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [November 4, 2014, 9:45am UTC](https://www.ruby-forum.com/t/messages-getting-dropped/232907/1 "2014-11-04T09:45:12Z")

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Hi list,

I have a strange problem with one of my custom blocks. It’s a char  
stream  
sink with a message output. It basically takes the input stream, selects  
a  
few samples, packs them into blobs, makes a pmt::cons out of it and  
publishes the message.

My original QA flowgraph looked like this:  
vector\_source\_b --\> my\_custom\_block --\> pdu\_to\_tagged\_stream --\>  
vector\_sink\_b

The flowgraph is run with tb.start(); time.sleep(2); tb.stop()

In this setup, I constantly lose the last of the 3 published packets. I  
made sure that the packets are actually published with a print statement  
right after the call to message\_port\_pub().

During debugging, I attached a message\_debug block to my\_custom\_block  
and  
now all messages are received, even at the vector sink. There has been  
no  
change to the custom block! I can reproduce the packet loss by  
commenting  
out the message\_debug block.

Any ideas what is happening here?

Felix

---

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**Author:** ![Felix\_W](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/bb73d2/32.png) [@Felix\_W](https://www.ruby-forum.com/u/Felix_W)\
**Post date:** [November 5, 2014, 3:24pm UTC](https://www.ruby-forum.com/t/messages-getting-dropped/232907/2 "2014-11-05T15:24:58Z")

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On 04.11.2014 09:43, Felix W. wrote:

> Hi list,
> 
> I have a strange problem with one of my custom blocks. It’s a char stream  
> sink with a message output. It basically takes the input stream, selects a  
> few samples, packs them into blobs, makes a pmt::cons out of it and  
> publishes the message.

Your issue might be different, but I experienced problems with the block  
as well.

Please see bug #751.

–merlin

[http://gnuradio.org/redmine/issues/751](http://gnuradio.org/redmine/issues/751)