If you want to share a filehandle with all threads, there is no need to pass it to each thread individually. Just open it before you spawn your threads and they will inherit a cloned copy of it. Ie. This runs without errors:

#!/opt/coolstack/bin/perl  -w
use strict;
use threads;
use threads::shared;
use FileHandle;

my $nthreads = 64;
my $x : shared; # For sync
my $fh = FileHandle->new("> out.txt");

my @thrs;

for(1..$nthreads){
  print "START $_ \n";
  my ($thr) =  threads->create(\&worker, $_);
  push @thrs ,$thr;
}
$_->join for @thrs;
print "STOP: " . localtime() . "\n";
$fh->close;
print `wc -l out.txt`;
exit;

#----------------------------------------------------
sub worker{
  my $id = shift;
  my $tmp;

  for(1..1000){
    lock $x;
    print $fh "bla blalbla bla blal bla bla bla bla\n" ; #NOT SHARED!!
+!!
  }
  print "$id>LOAD EXIT\n";
}
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And produces:

c:\test>junk4
START 1
START 2
1>LOAD EXIT
START 3
2>LOAD EXIT
START 4
3>LOAD EXIT
...

START 60
59>LOAD EXIT
START 61
60>LOAD EXIT
START 62
61>LOAD EXIT
START 63
62>LOAD EXIT
START 64
63>LOAD EXIT
64>LOAD EXIT
STOP: Tue May 19 11:37:09 2009
  64000 out.txt
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