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While a lot of effort has gone into making it difficult or impossible to crash the Python interpreter in normal usage, there are lots fairly easy ways to crash the interpreter. The BDFL pronounced recently on the python-dev mailing list:

    I'm not saying it's uncrashable. I'm saying that if you crash it, it's a
    bug unless proven harebrained.

I thought it might be worthwhile to document some ways the interpreter can be crashed so that people can learn where they need to tread lightly.

Bogus Input

Through Python 2.4 you could crash the interpreter by redirecting stdin from a directory:

    % python2.4 -c 'import sys ; print sys.version'
    2.4.1 (#3, Jul 28 2005, 22:08:40) 
    [GCC 3.3 20030304 (Apple Computer, Inc. build 1671)]
    % python2.4 < .
    Bus error

Starting with 2.5 the interpreter notices and aborts:

    % python2.5 -c 'import sys ; print sys.version'
    2.5a0 (41847M, Dec 29 2005, 22:21:03) 
    [GCC 3.3 20030304 (Apple Computer, Inc. build 1671)]
    % python2.5 < .
    Fatal Python error: <stdin> is a directory
    Abort trap

Exhausting Resources

There are a number of areas where resource exhaustion can crash the interpreter. Here's one fairly easy to demonstrate way to do it though:

    % python
    Python 2.5a0 (41847M, Dec 29 2005, 22:21:03) 
    [GCC 3.3 20030304 (Apple Computer, Inc. build 1671)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import sys
    >>> sys.setrecursionlimit(1<<30)
    >>> f = lambda f:f(f)
    >>> f(f)
    Segmentation fault

Dangerous Modules

Some modules are designed to allow programmers access to the guts of things. Naturally, they also give programmers the opportunity to shoot themselves in the foot. Here are a few.

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