Experimental Physics and
Industrial Control System

Hi again,

It seems that if I create a CA context before importing the p4p client, it all works fine. It is still a mystery for me, but it seems to be a good workaround for the moment.

import epics

epics.ca.create_context()

import p4p.client.thread

Cheers,

Juan

Hi all,

I have been using CA and PVA clients in Python for some time, but in the last few days I started to have issues. I recently updated to macos Catalina and python 3.7.7, and I am using epics base 7.0.4.

I wrote a small script to reproduce my issues:

import time

from __future__ import print_function

import epics

import p4p.client.thread

pv = epics.PV('SOME:PV', connection_callback=lambda pvname,conn,pv: print('connected'))

time.sleep(1)

pv.connect(timeout=0)

pv.get()

This script fails to connect to the PV if I run it on python 3.7.7, using pyepics 3.4.2 with PYEPICS_LIBCA pointing to epics base 7.0.4, and p4p 3.5.1. Even trying to stop the python interpreter with ctrl-C doesn’t work, I have to kill the process. Removing the p4p import fixes the issue.

I tried different EPICS7 releases and all fail, while EPICSv3 seems to work just fine. Unsetting PYEPICS_LIBCA also works, because the internal ca lib is 3.16.

It also runs fine on python 2.7, with and without PYEPICS_LIBCA pointing to epics base 7.

Any clue where the issue might be? Thanks!

Best regards,

Juan