在makefile中运行应用程序时出现分段错误

Question

I had a program and I could only run it from Makefile otherwise it would give me this error:

Segmentation fault (core dumped)

But if I ran the application from Makefile it would be ok. I have simplified my code:

This is my make file:

all: 
    g++ aaa.cpp
run:
    ./a.out

and this is my code:

#include <iostream>
#include <armadillo>

class CModel
{
public:
    arma::mat::fixed<5,10000000> buffer;
};


int main()
{
    CModel m1, m2;
    std::cout<<"run successfully"<<std::endl;
    return 0;
}

It seem this is a problem with memory occupation when it is out of makefile but how come does it work when it is inside makefile?

$ make
g++ aaa.cpp
$ make run
./a.out
run successfully
$ ./a.out
Segmentation fault (core dumped)

Additional info:

OS: Linux (Ubuntu)

To use armadillo matrix library:

sudo apt-get install libarmadillo-dev

Answer 1

I don't have armadillo so I cannot test your code. However by looking at it I'm guessing you have a stack overflow. Which is a particular time of segmentation fault.

It is not uncommon for a segmentation fault to come and go depending on how the program is run (and the positions of the stars etc etc).

Try reducing the size of your stack. Try:

arma::mat::fixed<5,1000> buffer;

Instead of:

arma::mat::fixed<5,10000000> buffer;

Or if it really does have to be that size put it on the heap instead of the stack (use the new/delete). High memory usage instances should not be on the stack and always on the heap.

Answer 2

Use heap instead of stack:

int main()
{
    CModel *m1 = new CModel;
    CModel *m2 = new CModel;
    std::cout<<"run successfully"<<std::endl;
    delete m1;
    delete m2;
    return 0;
}

Of course, you'll need to use m1->SomeMember instead of m1.SomeMember