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### How can I add a timeout to a charpoly calculation?

For some reason after a bunch of matrix charpoly calculations, charpoly hangs on me. I suppose it's some memory problem, but rather that fix that, I just want to put a timeout on the calculation and then restart it if it hangs.

The problem is I can't use the "alarm" solution given in the answer to this question because sage.matrix.matrix_integer_dense.Matrix_integer_dense.charpoly doesn't catch the KeyboardInterrupt:

sage: M = random_matrix(ZZ,1000,1000)
sage: alarm(30)
sage: try:
....:     P = M.charpoly()
....: except KeyboardInterrupt:
....:     print "did not complete!"
....:


What is another approach I could use?