Memory leak with Mex

Question

Sridutt Nayak 2013-3-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/66677-memory-leak-with-mex

I am doing below in a loop with dims = [1024 768 256]

1. I want to read a set of block loaded by block_iter(1 to 16) into a RAM of Hardware. The memory call seems to display the memory leaking. Am I doing it wrong somewhere?

// Create memory for reading in data
        mxArray *B= mxCreateNumericArray(3,dims,mxUINT8_CLASS,mxREAL); 
        mxArray *in = mxCreateDoubleMatrix(1, 1, mxREAL);
// See Memory usage
          mexCallMATLAB(0,NULL,0,NULL,"memory");
          memcpy(mxGetPr(in), &block_iter, sizeof(double)*1*1);
// Read a block of 256 images of 1024*768. Even the temp variable is cleared in the dmd_feeder function
          mexCallMATLAB(1,&B,1,&in,"data_feeder");
//Call RAM_FILL
          ram_fill(d,B);  // As of now does nothing, its an empty void function and I would be replacing it to copy data to ram of hardware.
//Deallocate memory;
        mxDestroyArray(B);
        mxDestroyArray(in);

PS: The memory leak is around 192 MB each loop which is exactly the amount of data in array B

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Jan 2013-3-11

What is "a loop with dims"? What is "block_iter(1 to 16)"? What does "memory exactly reply"? Do you mean the size of the largest available block or the sum of the free memory? What happens inside "data_feeder"? What is "d" in the call of ram_fill() and are you really sure, that this function does not matter? If so, why do you include it in the example?

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Answer 1

James Tursa 2013-3-11

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https://ww2.mathworks.cn/matlabcentral/answers/66677-memory-leak-with-mex#answer_78177

编辑：James Tursa 2013-3-11

在 MATLAB Online 中打开

You are leaking memory behind the B mxArray. E.g.,

mxArray *B= mxCreateNumericArray(3,dims,mxUINT8_CLASS,mxREAL); 
    :
mexCallMATLAB(1,&B,1,&in,"data_feeder");

The mxCreateNumericArray call allocates memory for the mxArray B. The subsequent mexCallMATLAB call allocates a brand new mxArray B. The call itself overwrites the value of B with a new value. The currently existing B value from your previous mxCreateNumericArray call becomes lost and thus you leak the memory behind it (at least temporarily until the mex routine exits back to the calling function). You need to get rid of your mxCreateNumericArray call since mexCallMATLAB will allocate memory for the B result itself.