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Full Discussion: Performance issue
Top Forums UNIX for Dummies Questions & Answers Performance issue Post 302499390 by pludi on Thursday 24th of February 2011 09:46:59 AM
Old 02-24-2011
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.
 

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LEARN ABOUT REDHAT

merge

MERGE(1)						      General Commands Manual							  MERGE(1)

NAME

       merge - three-way file merge

SYNOPSIS

       merge [ options ] file1 file2 file3

DESCRIPTION

       merge  incorporates all changes that lead from file2 to file3 into file1.  The result ordinarily goes into file1.  merge is useful for com-
       bining separate changes to an original.	Suppose file2 is the original, and both file1 and file3 are modifications of  file2.   Then  merge
       combines both changes.

       A  conflict  occurs  if	both  file1 and file3 have changes in a common segment of lines.  If a conflict is found, merge normally outputs a
       warning and brackets the conflict with <<<<<<< and >>>>>>> lines.  A typical conflict will look like this:

	      <<<<<<< file A
	      lines in file A
	      =======
	      lines in file B
	      >>>>>>> file B

       If there are conflicts, the user should edit the result and delete one of the alternatives.

OPTIONS

       -A     Output conflicts using the -A style of diff3(1), if supported by diff3.  This merges all changes leading from file2  to  file3  into
	      file1, and generates the most verbose output.

       -E, -e These  options  specify conflict styles that generate less information than -A.  See diff3(1) for details.  The default is -E.  With
	      -e, merge does not warn about conflicts.

       -L label
	      This option may be given up to three times, and specifies labels to be used in place of the corresponding  file  names  in  conflict
	      reports.	 That  is, merge -L x -L y -L z a b c generates output that looks like it came from files x, y and z instead of from files
	      a, b and c.

       -p     Send results to standard output instead of overwriting file1.

       -q     Quiet; do not warn about conflicts.  -V Print 's version number.

DIAGNOSTICS

       Exit status is 0 for no conflicts, 1 for some conflicts, 2 for trouble.

IDENTIFICATION

       Author: Walter F. Tichy.
       Manual Page Revision: 5.7; Release Date: 1995/06/01.
       Copyright (C) 1982, 1988, 1989 Walter F. Tichy.
       Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.

SEE ALSO

       diff3(1), diff(1), rcsmerge(1), co(1).

BUGS

       It normally does not make sense to merge binary files as if they were text, but merge tries to do it anyway.

GNU
								    1995/06/01								  MERGE(1)
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