Re: Poor randomness with File::Temp and fork().


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Re: Poor randomness with File::Temp and fork().

by Zaxo (Archbishop)

on Jun 28, 2004 at 00:12 UTC ( [id://370065]=note: print w/replies, xml )

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in reply to Poor randomness with File::Temp and fork().

Here's a demonstration of several processes inheriting rand's seed. The srand solution suggested seems necessary if anything seeds rand before fork.

#!/usr/bin/perl
my ($foo, %kid) = rand;
for (1..10) {
    $kid{my $cpid = fork} = undef;
    defined $cpid or delete( $kid{""}), next;
    $cpid and next;
    print rand, $/;
    exit(0);
}
delete $kid{+wait} while %kid;
__END__
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
0.292121652604209
[download]

With srand; inserted as the first thing in each child, we get, say,

0.458016411009343
0.922388048683391
0.938946679075347
0.358693821662204
0.88636225422761
0.519188953171582
0.459808857952343
0.982476360703917
0.626396972061233
0.824876680345373
[download]

After Compline,
Zaxo