Monitor timeouts with asyn/StreamDevice, and issues in DRTO with UDP

[Érico Nogueira Rolim via Tech-talk <tech-talk at aps.anl.gov>]

Hi!

I'm using StreamDevice with a UDP device, and we have been observing some communication timeouts caused by packet drops/high CPU load (per our testing), which we only noticed due to actually opening the IOC shell and seeing multiple "No reply within 1000 ms to ..." messages. However, I'd like to be able to observe these (instantaneous) timeouts from a PV. Checking the alarm of the PVs isn't enough, because it's cleared as soon as the next communication attempt works, and having to check our archiver data for the information doesn't scale well for operation.

I instantiated the asynRecord for our port, and tried setting .DRTO to "Yes", in order to observe disconnections (which I simulated by fully disconnecting the ethernet cable from the device). The .CNCT field does go to "Disconnect", but it goes back to "Connect" for every record that is processed, and displaying the timestamp of the PV in an interface wouldn't be enough, because it is "<undefined>" (per camonitor output). Furthermore, in what seems to be a bug, once I reconnect the ethernet cable, the iocsh prints the following messages:

2023/09/18 15:30:55.702487 TIPORT DE-23RaBPM:TI-EVE:readAndUpdate: device TIPORT 0 disconnected
** reconnected cable **

2023/09/18 15:30:55.800291 TIPORT DE-23RaBPM:TI-EVE:FrmVersionA-Cte: StreamCore::lockCallback(StreamIoSuccess) called unexpectedly

and from this point on, it simply doesn't reestablish a connection. Pulling the cable again doesn't cause anything to be printed in iocsh anymore, and the records have stopped being updated (though at least they do have alarm information). I can provide more information, if necessary :)

Is there some other way of monitoring timeouts and disconnections when using asyn/StreamDevice which I'm missing?

Cheers,

Érico

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