Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Wed, 30 Nov 2016 19:40:53 +0100

Hi Kevin

On 29.11.2016 10:31, Kevin Meyer wrote:
> Responses inline, below, but basically: the SNL thread is still running:
> 
> ----- On 28 Nov, 2016, at 17:31, Kasemir, Kay [email protected] wrote:
> 
>>> In one of the sequencers, I have a call out to to a Python script that calls a
>>> web service (to Olog, to create an electronic lab-book entry).
>>
>> Is that the one that's occasionally hanging up?
>>
>> Are you calling out to python from somewhere within the SNL code, like
>>
>> when (..)
>> {
>>    .. call out to python
>> }
>>
>> ?
>>
>> I assume that all the SNL code is executed within some 'main' thread of the
>> sequencer.
>> Maybe the call out to python hangs, so the core SNL thread is stuck and no
>> longer updating anything.

No this is not the case as you found out. A separate thread is spawned
for each state set.

Does you Python program use CA? If yes, then I have a theory: the
problem comes from the Python program trying to create a CA client
context, but ending up re-using the one from the state thread. And when
the Python ends, the context is destroyed, effectively disabling the
state thread's CA capability.

To test this, replace the Python program with a very simple program that
does not import any CA stuff. If the problem persists this means my
guess was wrong.

Cheers
Ben
-- 
"Make it so they have to reboot after every typo." ― Scott Adams

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System