How to opening 1 instance of MATLAB from MATLAB, but accessing it multiple times

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Ali Razavi
Ali Razavi on 17 Aug 2021
Commented: Ali Razavi on 19 Aug 2021
Hello,
I would like to do the followings:
  1. From a MATLAB session, open another instance of MATLAB - which can be done by: !matlab &
  2. Every now and then from existing MATLAB session have a command executed in the other session. This is the part that I do not know how to do. How in existing MATLAB session, I can have a command exscuted on another instance I already opened.
I greatly appreciate your suggestions.
  3 Comments
Raymond Norris
Raymond Norris on 17 Aug 2021
Does the second MATLAB have to have its Desktop visible to interact with or does it suffice to be running in "headless" mode?
Do you have the Parallel Computing Toolbox?

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Accepted Answer

Raymond Norris
Raymond Norris on 18 Aug 2021
Using the Parallel Computing Toolbox, look at parpool and parfeval. parpool will start a N number of "workers" (i.e. headless instances of MATLAB), which can be running either on your local machine (supported out of the box) or on a remote machine (additional work to setup). parfeval offloads execution to a worker. For example
% Initialization: get a handle to the cluster and start a pool of 1 worker
cluster = parcluster;
pool = cluster.parpool(1);
% ... run other code ...
% Spawn command to run on worker
pool.parfeval(@mycode,0,{});
parfeval is non-blocking and can be called whenever you want to offload code. The {} is the input arguements to calling mycode. If you code has input args, assign them into {}.
If your code returns a result, then you'll need to assign it a result so that you can pull the result(s) back. You won't be notified when the code finishes, so you'll need to verify that the state has finished.
f = pool.parfeval(@mycode,1,{});
% ... run other code ...
% Get results
f.wait
result = f.fetchOutputs;
See the doc for parfeval for more information. One consideration is that a pool will expire if not used after a period of time (default is 30 minutes). You can disable this auto-deletion in the parallel preferences.
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More Answers (2)

Ali Razavi
Ali Razavi on 18 Aug 2021
Edited: Ali Razavi on 18 Aug 2021
Hello,
Thanks.
Answering your questions:
Q1. Does the second MATLAB have to have its Desktop visible to interact with or does it suffice to be running in "headless" mode?
A1. It can be "headless" and run in background. No interaction via desktop needed.
Q2. Do you have the Parallel Computing Toolbox?
A2. No. However, I would like to know how to do this in both options (with and without Parallel Computing Toolbox ).
Many thanks for the help.

Walter Roberson
Walter Roberson on 18 Aug 2021
As you are using Windows, one approach is to use .NET System.Diagnostics.Process https://www.mathworks.com/matlabcentral/answers/586706-how-to-redirect-standard-input-and-standard-output-using-net-system-diagnostics-process#answer_487475 to open a process connection, and write commands to the other MATLAB. The link shows how to redirect input and output.
Another possibility is to invoke MATLAB through actxserver() and use the Automation Engine facilities; https://www.mathworks.com/help/matlab/call-matlab-com-automation-server.html

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