Re: [Discuss-gnuradio] Flowgraph locking up with Stream Mux

[Nowlan, Sean]

Yes, that’s a workaround. My point is that this issue is not obvious to somebody who isn’t familiar with how the scheduler works.

 

When using null sources, it makes sense to just use two of them. But what if you’re supplying a data stream and need to inject a synchronization sequence in the middle, as GSM does? In this case, my workaround is using a Deinterleave block to split a burst of data into two branches fed to the first and third ports of a Stream Mux, and a Vector Source with the sync sequence fed to the second Mux port. This works fine for me.

 

I still wonder if there’s a way to prevent people from stumbling into the issue that’s causing the lock up.

 

Sean

 

 

From: Richard Bell [mailto:address@hidden
Sent: Thursday, July 09, 2015 3:40 AM
To: Nowlan, Sean
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] Flowgraph locking up with Stream Mux

 

I think it's the fact that you are feeding two different ports of the mux by one null source that is the issue. The first ports buffer fills before the third ports buffer does. When the first is full, it prevents null source from creating new outputs, which will cause the graph to stall on the third port waiting for items. 

Use two distinct null sources and I think it will run fine. 

Sent from my iPhone

On Jul 8, 2015, at 7:26 PM, Nowlan, Sean <address@hidden> wrote:

I’m somehow getting a simple flowgraph to lock up GNU Radio. It locks up every time I run it, after roughly the same amount of time. As you can see in the attached image and GRC file, I’m feeding two inputs of a Stream Mux block from the same upstream block. Do you imagine why that might cause problems?

 

I know there are other ways to do what I’ve shown here, but locking up seems like a bug.

 

Thanks,

Sean

<simple_failing_flowgraph.png>

<stream_mux_bug_test.grc>

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