matlab::engine::connectMATLAB with current session stalling in Matlab

1 次查看（过去 30 天）

显示更早的评论

marc markoh 2019-4-22

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/457824-matlab-engine-connectmatlab-with-current-session-stalling-in-matlab

关闭： MATLAB Answer Bot 2021-8-20

Problem:

Matlab stalled in a "Busy" state when calling a C dll.

Background:

I want to create a dll and call it from matlab to interact with my current workspace. The matlab::engine tool has the necessary features to enable what is desired, so I compiled a c dll function with the following:

__declspec(dllexport) void
C_VLInit() {
    using namespace matlab::engine;
    std::unique_ptr<MATLABEngine> matlabPtr = connectMATLAB(u"currentSession");
    matlab::data::Array aRes = matlabPtr->getVariable(u"a");
    double a = aRes[0];
    
    matlabPtr->eval(u"y = 1");
    matlab::data::Array yRes = matlabPtr->getVariable(u"y");
    double y = yRes[0];
    
    std::cout << "current val of a : " << a << "\n" << std::endl; /* not supported in matlab; used for python */
    std::cout << "current val of y : " << y << "\n" << std::endl; /* not supported in matlab; used for python */	
    
    return;
}

In Matlab, I ran the following to create a shared session and called the dll above:

>> matlab.engine.shareEngine('currentSession');
>> a = 93423;
>> toHeader = 'path\to\vLink.h';
>> toDll    = 'path\to\vLink.dll';
>> loadlibrary(toDll, toHeader)
>> calllib('vLink', 'C_VLInit');

The issue is my matlab stays in a "busy" state inside the calllib function.

Minimal example showing the DLL works outside of Matlab

I was curious if there was an issue with the dll, so I created this python workflow to test if the dll can latch onto my matlab "currentSession". I ran python from the windows command line. It seems to work with my currect dll, with this as the output:

>>> from ctypes import *
>>> _lib = cdll.LoadLibrary(r'path\to\vLink.dll')
>>> _lib.C_VLInit()
y =
     1
current val of a : 93423
current val of y : 1

Question:

Any ideas why matlab could stall and stagnate in a "busy" state after/in the calllib function?
Am I applying any incorrect steps above in how to connect to the matlab "currentSession" in the dll?
Will matlab::engine work within a dll called from matlab itself?
Are there any obvious signs of errors?