Experimental Physics and
Industrial Control System

Ø  To me, looping with “caput_one_pv_at_a_time” seems inefficient, especially in the Python world where “list” is a daily-usable data structure.

That may be true, but it does not really address the issue Marco is reporting, which is unexpectedly poor behavior with single caput operations.

Marco, since you are using streamDevice in your IOC and the loopback IP address that means you must have created an drvAsynIPPort port for the communication.  The first line of debugging you should use is to enable asynTraceIODriver on that port.  That will show you exactly what is being sent on the network without needing to run tcpinfo.  In your IOC st.cmd add these lines:

asynSetTraceIOMask(portName, 0, ESCAPE)

asynSetTraceMask(portName, 0, ERROR|DRIVER)

where portName is the name you gave to the drvAsynIPPort.

This will show the communication over that socket.  See if it agrees with what tcpinfo shows.

Mark

Hello Marco,

To me, looping with “caput_one_pv_at_a_time” seems inefficient, especially in the Python world where “list” is a daily-usable data structure.

I have been using another Python-based Channel Access tool named “cothread” where you simply caput a list of pvs associated with a list of values: cothread.catools.caput(pvs, values). In your case, cothread.catools.caput(a_list_of_records, VALUE, repeat_value=True).

I have used “cothread” in one application where I get ~200 BPM waveform data (100K doubles per BPM) in a few seconds by caget(bpm_wavform_pv_list). Basically the processing time is dominated by the limited network bandwidth. “cothread” is very efficient by using cooperative threading.

Take a look at these links:
https://github.com/dls-controls/cothread
https://cothread.readthedocs.io/en/latest/catools.html#cothread.catools.caput

Cheers,
Yong

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