Programmatically interrupt MATLAB on Windows

When using MATLAB through the GUI, I can easily interrupt a computation by pressing Ctrl-C.

Is there a way to do the same programmatically when using MATLAB through the MATLAB Engine C API?

On Unix systems there is a solution: send a SIGINT signal. This will not kill MATLAB. It'll only interrupt the computation (i.e. exactly what I want). I am looking for a solution that works on Windows.

Use case: this is for a Mathematica-MATLAB interface. I want to be able to forward interrupts from Mathematica to MATLAB. The functionality is working and implemented on Linux/OSX, but I'd prefer to have it for the majority Windows platform as well.

EDIT: I'm also interested in solution that work with the MEX interface. The MEX function would be multi-threaded where the first thread is running an evalc(), and the second is watching for interrupt conditions. How would the second thread interrupt the evalc()? I have less hope for this with MEX than with Engine though.

UPDATE: I still haven't found any way to do this with the Engine interface, but I did find something which might work with MEX. The libut library has a function called utSetInterruptPending(). When running sequentially, utSetInterruptPending(1) will interrupt MATLAB (as tested with calllib()). Does anyone know utSetInterruptPending() is safe to call in a MEX function from a different thread than the main one?

[Szabolcs]

Link to older cross post on StackOverflow.

[Iain]

I don't know what communications can exist between mathematica and matlab, however, you could poll for some kind of interrupt, and break out after receiving it.

[Szabolcs]

@iain The question is not specific to how the communication works. Please forget about Mathematica for a while, and imagine that you're writing a custom GUI for MATLAB and you're calling MATLAB through the Engine interface. How would you interrupt a long computation? The users of your GUI would want to be able to do this. Is the question more clear now?

[Iain]

I understood the question, but I don't know the answer. - Which is why I suggested an alternative method that could allow you to temporaily interrupt the execution and do something else before continuing.

[Szabolcs]

@Iain I don't understand what you are saying. What do you mean by " poll for some kind of interrupt, and break out after receiving it."? I don't have to poll, I know exactly when I receive the interrupt message (I receive it on a different thread). What do you mean by "break out", or "temporarily interrupt"? The precise problem is that I don't know how to stop MATLAB at all on Windows, either temporarily or permanently. The only thing I can do is make it quit completely.

[Iain]

I mean if you, in your matlab code, check to see if something has been done, say, a file being written to a known location, and if so, have the matlab code either stop execution, or, say, execute the code in that file.

[Szabolcs]

@Iain I have no control over the code that's being run, so I can't do that.

Answer 1

[Walter Roberson]

MS Windows XP SP2 and later support POSIX signals including (presumably) SIG_INT.

[Szabolcs]

How can I send such a signal? And does MATLAB actually respond to it the same way as on Unix? I did find that Windows should support these signals, but I have not found a way to actually send them to other processes. The signal.h header does not have a kill() function like on Unix.

I did find this too, but that seems to be for command line programs only, and it doesn't seem to work at all when I try (I get a permission denied error).

[Walter Roberson]

It looks like the various tools available to send a signal to an id, do so by sending a WM_CLOSE or WM_TERMINATE message. Unfortunately MATLAB would not be able to tell those apart from user request to terminate the program.

I find evidence that console applications can bind in handlers for control-break, but matlab is not generally a console application and I do not know if it does that binding (and I have not seen yet how a different process can provoke it)

https://serverfault.com/questions/151196/how-does-windows-kill-a-process-exactly/151788

Answer 2

[Jan]

I assume, you do not want to stop the engine temporarily, like Ctrl-C in the application, but kill the job. Then the windows command taskkill will help.

[Szabolcs]

Actually what I need is interrupting MATLAB without killing it, i.e. the equivalent of Ctrl-C. (Quoting from the question: "This will not kill MATLAB. It'll only interrupt the computation (i.e. exactly what I want).") Killing it is easy, but I'm looking for a way to interrupt it without killing it.

[Jan]

What do you expect as internal state of an interrupted engine? When Matlab is not run as application with a GUI, I cannot imagine, what interrupting without killing can be useful for. Do you want to resume later one?

[Nilson Martinez-Lopez]

I have an example where I'd like to do this. I am running DAQ toolbox audio data input using startBackground(session). This is run from a callback function followed by wait(session). MATLAB is Busy, unless I use CTRL-C to stop it. I'd like to map a button from the UI to stop it in the same manner.

Answer 3

[Szabolcs]

I originally asked this question a very long time ago, when MATLAB only provided a buggy and limited C API (the "MATLAB Engine") for controlling it from another application.

Since then, MATLAB introduced a much better and much more flexible C++ Engine API.

I have not yet used this, but according to the documentation, it does have facilities for asynchronous evaluations and fo interruption.

https://www.mathworks.com/help/matlab/apiref/matlab.engine.futureresult.html#bvkf5h3-7

See FutureResult and its cancel() method.