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Well, here is an example I ran on the redhat boxes at work and my debian box at home, it shows bad data on both systems if run enough (usually 20 iterations will do it). I also added a check for syswrite... doesn't seem to be writing short data.

#!/usr/bin/perl use Fcntl qw(:DEFAULT :flock); use strict; my $FH; my $fn = 'flockdata'; my $test_data = (join('','a'..'z')."\n") x 10; #print length($test_data),"\n"; sysopen($FH,$fn,O_WRONLY|O_CREAT); for(1..10) { last unless fork(); } for(1..20) { die "FLOCK ERROR\n" unless flock($FH,LOCK_EX); die "SYSWRITE ERROR\n" unless syswrite($FH,$test_data,length($test_d +ata)) == \ length($test_data); flock($FH,LOCK_UN); } close $FH;
and to run it when named testflock.pl
perl -e 'system(q{perl testflock.pl ; ls -al flockdata; rm flockdata}) + for 1..20'

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In reply to Re^2: What the flock!? Concurrency issues in file writing. by suaveant
in thread What the flock!? Concurrency issues in file writing. by suaveant

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