How to prevent this from happening?

[Guest]

Regarding this expression: 1 << x

I had a bug in my code that made x become Very Large - much larger than
I had intended. This caused Python, and my PC, to lock up tight as a
drum, and it appeared that the Python task (Windows XP) was happily and
rapidly consuming all available virtual memory.

Presumably, Python was trying to create a really really long integer,
just as I had asked it.

Is there a way to put a limit on Python, much like there is a stack
limit, so that this sort of thing can't get out of hand?

 

[John Machin]

Regarding this expression: 1 << x

I had a bug in my code that made x become Very Large - much larger than
I had intended. This caused Python, and my PC, to lock up tight as a
drum, and it appeared that the Python task (Windows XP) was happily and
rapidly consuming all available virtual memory.

Presumably, Python was trying to create a really really long integer,
just as I had asked it.

Is there a way to put a limit on Python, much like there is a stack
limit, so that this sort of thing can't get out of hand?

If you mean a command line argument to specify an upper limit for the
RHS of a << operator, no there isn't one, and no there shouldn't be one.

To cater for sillinesses that aren't caught by exceptions (or where it
may be a very long time before the exception is triggered, as in your
case), I'd suggest placing tests close to the action. For example, if
you are doing some bit-bashing, "assert nshift <= wordsize" or something
like that may be appropriate.

 

[Serge Orlov]

Regarding this expression: 1 << x

I had a bug in my code that made x become Very Large - much larger than
I had intended. This caused Python, and my PC, to lock up tight as a
drum, and it appeared that the Python task (Windows XP) was happily and
rapidly consuming all available virtual memory.

Presumably, Python was trying to create a really really long integer,
just as I had asked it.

Is there a way to put a limit on Python, much like there is a stack
limit, so that this sort of thing can't get out of hand?

This is a general problem regardless of programming language and it's
better solved by OS. Windows has API for limiting resource usage but it
lacks user tools. At least I'm not aware of them, maybe *you* can find
them. There is Windows System Resource Manager
http://www.microsoft.com/technet/downloads/winsrvr/wsrm.mspx It won't
run on Windows XP, but you may take a look at its distribution CD
image. If you're lucky maybe there is a command line tool for Windows
XP.

Alternatively you can switch to a better OS Any Unix-like (Max OS X,
Linux, *BSD, etc...), they all have resource usage limiting tools out
of the box.