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Full Discussion: Performance issue
Top Forums UNIX for Dummies Questions & Answers Performance issue Post 302500092 by matrixmadhan on Sunday 27th of February 2011 12:22:18 AM
Old 02-27-2011
Quote:
Originally Posted by pludi
You're probably losing most of the time on the actual output. Each call to printf costs the time of a process spawn. And the file has to be opened, written, and closed on each call.

The below Perl script creates the permutations (same number of records as in your example) in just over 2 minutes on an average sized laptop
Code:
# ./perm.pl
Thu Feb 24 15:28:41 CET 2011
Thu Feb 24 15:30:56 CET 2011
# cat perm.pl
#!/usr/bin/perl

use strict;
use warnings;

my ( $fh1, $fh2, $fh3, $out );
my ( @file1, @file2, @file3 );
system("date");
{
    local $/;
    open $fh1, '<', 'file1';
    my $file1 = <$fh1>;
    @file1 = split /\n/, $file1;
    close $fh1;
}
{
    local $/;
    open $fh2, '<', 'file2';
    my $file2 = <$fh2>;
    @file2 = split /\n/, $file2;
    close $fh2;
}
{
    local $/;
    open $fh3, '<', 'file3';
    my $file3 = <$fh3>;
    @file3 = split /\n/, $file3;
    close $fh3;
}

chomp @file1;
chomp @file2;
chomp @file3;

open $out, '>', 'file2.txt';
foreach my $first (@file1) {
    foreach my $second (@file2) {
        foreach my $third (@file3) {
            printf $out "%-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s\n",
              $first, $second, $third, 4, 5, 1, 2, 1, 5, 2;
        }
    }
}
close $out;
system("date");

---------- Post updated at 15:46 ---------- Previous update was at 15:38 ----------

Addendum: on the very same setup, the script as you have given it managed to produce ~50% of all combinations in about 17 minutes. There has to be something entirely different wrong with your setup for it to take 70 hours.
I would suggest to use perl builtin for time elapsed in seconds instead of using system call for date. But really minor.
 

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LEARN ABOUT LINUX

pam_issue

PAM_ISSUE(8)							 Linux-PAM Manual						      PAM_ISSUE(8)

NAME

       pam_issue - PAM module to add issue file to user prompt

SYNOPSIS

       pam_issue.so [noesc] [issue=issue-file-name]

DESCRIPTION

       pam_issue is a PAM module to prepend an issue file to the username prompt. It also by default parses escape codes in the issue file similar
       to some common getty's (using x format).

       Recognized escapes:

       d
	   current day

       l
	   name of this tty

       m
	   machine architecture (uname -m)

       

	   machine's network node hostname (uname -n)

       o
	   domain name of this system

       
	   release number of operating system (uname -r)

       	
	   current time

       s
	   operating system name (uname -s)

       u
	   number of users currently logged in

       U
	   same as u except it is suffixed with "user" or "users" (eg. "1 user" or "10 users")

       v
	   operating system version and build date (uname -v)

OPTIONS

       noesc
	   Turns off escape code parsing.

       issue=issue-file-name
	   The file to output if not using the default.

MODULE TYPES PROVIDED

       Only the auth module type is provided.

RETURN VALUES

       PAM_BUF_ERR
	   Memory buffer error.

       PAM_IGNORE
	   The prompt was already changed.

       PAM_SERVICE_ERR
	   A service module error occurred.

       PAM_SUCCESS
	   The new prompt was set successfully.

EXAMPLES

       Add the following line to /etc/pam.d/login to set the user specific issue at login:

		   auth optional pam_issue.so issue=/etc/issue

SEE ALSO

       pam.conf(5), pam.d(5), pam(7)

AUTHOR

       pam_issue was written by Ben Collins <bcollins@debian.org>.

Linux-PAM Manual						    06/04/2011							      PAM_ISSUE(8)
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