I'm implementing a recursive subroutine to find all the permutations of elements in a list of lists. You can look here to find out more on that subroutine.
Unfortunately, with the way the subroutine is implemented, the interpreter complains when a certain level recursion is reached. Inside the debugger, it complains when the 100th level of recursion is hit and exits("100 levels deep in subroutine calls!" is the error message).
It's not like the elements I'm using are particularly memory intensive. A conservative estimate would be that 2,000 characters are being pushed around at most at any one time. So it may actually be a limitation on the size of the call stack perhaps?
I'm running under Linux (one of the most recent ones, can't recall the exact version number) with 250 MB of RAM and generally 190MB free at any moment. | [reply] |
According to the perl manpage, "Recursion is of unlimited depth"
Perhaps your problem is with the debugger? Perl will generate the warning when you get 100 levels deep if you have warnings turned on, but it shouldn't die on you. What happens when you run the script without the debugger?
I agree that the problem isn't likely to be memory usage; you can run the program while watching the output from top sorted by memory to confirm that.
Could you post some sample data so we can try to reproduce your error?
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Actually, I change my original answer. After studying the alogigrithm and my implementation and use (as well as taking your advice and running top), my resources get clobbered. After I get up around 3000K of free memory or so, the process get killed. I'll probably just need to reimplement the algorithm in an iterative fashion...hey this can be my new question to your gurus. How can I reimplement merlyn's algorithm that I link above in an iterative fashion? :)
Thanks,
Bamafan
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Usually when you bomb out of a deep recursion, you have reached your stack size limit. If you are on a Unixy system, use ulimit -s or ulimit -a to see your stack size limit. If you are lucky you can increase it yourself, if not you'll have to tweak the kernel-imposed limit.
CU
Robartes-
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