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For 2023 (and 2024 ...) - we are now fully retired from IT training.
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max array size

Posted by chuckster (chuckster), 24 March 2003
I am trying to find out what is the max array size to read in a directory. This is on a sun box.

Posted by admin (Graham Ellis), 25 March 2003
A list in Perl (used to be called an array) is limited in the number of elements it can contain only by the addressing range of the system, and be the amount of memory and swap space that's available to your process.   In other words, if you're looking to hold a list of all the file names in a directory in a list, you should have no problem at all.

Example:

Code:
#!/usr/bin/perl

for ($k=0; $k<$ARGV[0]; $k++) {
       $list[$k] = $k;
       }

print "OK\n";


[localhost:~/mar03] graham% ./biglist 1000
OK
[localhost:~/mar03] graham% ./biglist 10000
OK
[localhost:~/mar03] graham% ./biglist 100000
OK
[localhost:~/mar03] graham% ./biglist 1000000
OK
[localhost:~/mar03] graham% ./biglist 10000000
OK
[localhost:~/mar03] graham%

I could really here the disc swapping in the last example ...

Test program run on a laptop running OSX; I'm very familiar with Sun and Solaris - same rules / criteria apply.


Posted by admin (Graham Ellis), 25 March 2003
It's probably way beyond what the original questioner expected, but I thought I would run my test program asking for an even bigger list:

Quote:
[localhost:~/mar03] graham% ./biglist 100000000
*** malloc[293]: error: Can't allocate region
Out of memory!
[localhost:~/mar03] graham%


To give you an idea, it ran for quite a while, occupied 211M of my 256M of physical memory and well over 3Gbytes of swap space before it crashed out.


Posted by chuckster (chuckster), 26 March 2003
Thank you for those answers. Much appreciated  



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