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Calling matlab.eng​ine.connec​t_matlab() twice freezes Python

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I can connect to a named running MATLAB session from Python with:
In [8]: matlab.engine.connect_matlab('MY_SESSION')
But if I call it a second time Python hangs for about a minute before finally saying it can not connect
In [8]: matlab.engine.connect_matlab('MY_SESSION')
Out[8]: <matlab.engine.matlabengine.MatlabEngine at 0x1648f46a370>
In [9]: matlab.engine.connect_matlab('MY_SESSION')
EngineError: Unable to connect to MATLAB session 'MY_SESSION'.
I can not find a way of testing if MY_SESSION already exists. I also can not find a way to close a connection that already exists in a different scope. Are those things possible?

Answers (1)

Chris on 29 Jan 2023
Edited: Chris on 29 Jan 2023
names = matlab.engine.find_matlab()
if 'MY_SESSION' in names:
eng = matlab.engine.connect_matlab('MY_SESSION')
You can del(eng) to close the connection in the present scope, but I'm not sure about forcing it closed from somewhere else.
Since Matlab takes a bit to do its thing, connecting/reconnecting will sometimes throw an error. You might use a try/except or a while loop to handle the error in a python script/program.
Chris on 30 Jan 2023
Edited: Chris on 30 Jan 2023
Then if the variable is present, the connection is there. Make a function that tests that condition before connecting.
Rob Campbell
Rob Campbell on 30 Jan 2023
We are getting side tracked now.
I want a way to test whether the connection has been made and it looks like that does not exist.
Thanks for trying, though.

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