Re: [Discuss-gnuradio] Flowgraph heartbeat pulse

[CEL]

Be a bit careful there, Throttle doesn't work like that! 
Throttle will sleep for as long as it takes to pass the number of input
items it sees.

For example, if you connected

Constant Source(1) -> Throttle (1 S/s) -> UDP Sink

Then, on start of the flow graph, "constant source" will produce e.g.
4096 items, and then Throttle's work will be called with these 4096
items. Throttle then calculates #input_items/sample_rate = 4096s and
sleep, for more than an hour, then signal it's finished copying thes
4096 items to the output. This is everything but a usable watchdog!

Frankly, I know (very, very well) that GNU Radio isn't bug-free.
But if your flow graph occasionally breaks, then you need to fix that,
and not only try to figure out when that happens. This is especially
hard in GNU Radio, since all blocks run in different threads, and a
disjunkt watchdog subgraph might just as well continue running after
your main graph has ceased to function.

I interpret your "sometimes values are missing" as "but then it
continues working normally afterwards". I'm certain that means your
flow graph is *not* crashing, because then it wouldn't continue working
normally after. What might happen is that some step or external factor
needs to much resources of your computer, and then the real time
processing of your input data (wherever that comes from!) can't be
sustained, leading to your external data source (SDR device?) having to
 drop samples. But then you'll need to debug your computation and
computational system to make it sufficienly reliable at not consuming
more time to do whatever you do to the signal than it takes to produce
the signal!

Vitals are still a good idea, but sadly, I don't have a standard way of
doing them.

Best regards,
Marcus

On Sun, 2018-04-01 at 04:20 +0000, Gilad Beeri (ApolloShield) wrote:
> Might work for you:
> Any kind of source, throttled to 1/HEARTBIT_INTERVAL, to a UDP sink.
> Example:
> Constant Source(1) -> Throttle (1 S/s) -> UDP Sink
> will write the number 1 to the designated UDP sink, once every
> second.
> 
> 
> On Sun, Apr 1, 2018 at 12:22 AM Milos Milosavljevic <milos.milosavlje
> address@hidden> wrote:
> > Hi All,
> > 
> > I was wondering if someone can give me some hints on the below
> > please.
> > 
> > I have a flowgraph running continuously demodulating some off air
> > signals and spitting out meta data about the parameters, calculated
> > SNRs, BER, freq offset estimations, etc. That meta and output data
> > is parsed regularly and saved to a database. 
> > 
> > However, sometimes it is either meta missing or data or both. I am
> > convinced that the flowgraph either stalls or crashes. I need to
> > capture it where exactly but first I want to develop a tool to
> > monitor the flowgraph to now when it crashed or hanged.
> > 
> > So I want to add a hearbeat somewhere which I can monitor and know
> > exactly that it is not running anymore. Does anybody have any ideas
> > of what would be the best way to do it? Can I use something from
> > the library for this? 
> > 
> > Any suggestions will be appreciated.
> > 
> > Many thanks,
> > Milos
> > 
> > _______________________________________________
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> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
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