ExecutionMode set to pyenv in matlab batch mode is not persistent

According to pyenv documentation (from https://mathworks.com/help/matlab/ref/pyenv.html):

> Use pyenv to change the default version or execution mode of the Python® interpreter. These changes are persistent across different MATLAB® sessions.

However, in both R2022a on Windows and R2022b on Linux I am experiencing that the changes done by pyenv are not persistent when they are done in batch mode.

In particular, the following happens. If I just call, it gives the value that I set in the MATLAB gui:

matlab -batch "pyenv().ExecutionMode"

ans =

  ExecutionMode enumeration

    OutOfProcess

However, if I try to set the value in batch mode, it does not seem that the changes are saved. It is trivial to see this by executing in sequence:

matlab -batch "pyenv().ExecutionMode"
matlab -batch "pyenv(ExecutionMode='InProcess')"
matlab -batch "pyenv().ExecutionMode"
matlab -batch "pyenv(ExecutionMode='OutOfProcess')"
matlab -batch "pyenv().ExecutionMode"

I would expect that the first call returns the value of ExecutionMode already set, while the third and the fifth command return `OutOfProcess` and `InProcess` . Instead, this does not happens, and the value set is always the one set originally:

C:\Users\STraversaro>matlab -batch "pyenv().ExecutionMode"

ans =

  ExecutionMode enumeration

    OutOfProcess
    
C:\Users\STraversaro>matlab -batch "pyenv(ExecutionMode='InProcess')"

ans =

  PythonEnvironment with properties:

          Version: ""
       Executable: ""
          Library: ""
             Home: ""
           Status: NotLoaded
    ExecutionMode: InProcess
    
    
C:\Users\STraversaro>matlab -batch "pyenv().ExecutionMode"

ans =

  ExecutionMode enumeration

    OutOfProcess
    
C:\Users\STraversaro>matlab -batch "pyenv(ExecutionMode='OutOfProcess')"

ans =

  PythonEnvironment with properties:

          Version: ""
       Executable: ""
          Library: ""
             Home: ""
           Status: NotLoaded
    ExecutionMode: OutOfProcess

C:\Users\STraversaro>matlab -batch "pyenv().ExecutionMode"

ans =

  ExecutionMode enumeration

    OutOfProcess

Is this the expected behaviour? There is any way of settng this value in a persistent way in batch mode? Thanks a lot in advance!

Answer 1

[Mann Baidi]

Hi Silvio,

I understand that you are facing issue in changing the pyenv.ExecutionMode() using the batch command. I suggest you try changing the variable using the MATLAB command window.

You can take the reference from the following link.

Out-of-Process Execution of Python Functionality - MATLAB & Simulink - MathWorks India

Hope this helps!

[Silvio Traversaro]

Thanks for the reply. For our use case, we would need to the change the `pyenv.ExecutionMode()` in an automatic way in a script, without any user intervention. Do you know have any idea if we can do that via the MATLAB command window? Thanks!

Answer 2

[Mann Baidi]

Hi,

I think you can directly change the ExecutionMode using script also, You can just type:

pyenv()

ans = 
  PythonEnvironment with properties:

          Version: "3.10"
       Executable: "/usr/bin/python3"
          Library: "libpython3.10.so.1.0"
             Home: "/usr"
           Status: NotLoaded
    ExecutionMode: InProcess

Then change the Execution Mode

pyenv("ExecutionMode","OutOfProcess")

ans = 
  PythonEnvironment with properties:

          Version: "3.10"
       Executable: "/usr/bin/python3"
          Library: "libpython3.10.so.1.0"
             Home: "/usr"
           Status: NotLoaded
    ExecutionMode: OutOfProcess

The pyenv.ExecutionMode would then be:

pyenv().ExecutionMode

ans = 
  ExecutionMode enumeration

    OutOfProcess