Here's another way to crash MATLAB!

May 17, 2012 at 8:00 am (crap data structures, dumb memory management)

Now that we know MATLAB’s memory manager has some problems with actually cleaning up too many objects at once, we can have some fun with it!

function pushdown(N, crash)
    %an N of more than about 1000000 with crash=1 is interesting.
    a = {};
    for i = 1:N
        a = {rand() a};
    end

    if ~exist('crash', 'var') || ~crash
        %feed it to matlab's deallocator one piece at a time, or it will choke.
        for i = 1:N
            a = a{2};
        end
    end
end

First try running:

>> pushdown(1000000)

Then try:

>> pushdown(1000000, 1)

What do you get? I get a hard crash.

So not only can you blow the interpreter stack with deallocation, you can blow the C stack as well!

I mean, a system can get by for some purposes without garbage collection… but not when reference-counting is done this badly.

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