As given, the benchmark didn't complete within more than half an hour (not sure why this is so excruciatingly slow). So I stopped it, and reduced the string length 

my $str = 'x' x 1_000_000;
...
cmpthese 100,
...

[download]

Results (similar on both above machines/versions of Perl): 

          Rate Threads   Forks
Threads 2.02/s      --     -4%
Forks   2.11/s      5%      --

[download]

(which is not all that surprising, I guess, as modifying the string results in copy-on-write, which destroys fork's advantage)

Also, the time taken to fiddle with the string here far outweighs the time needed to create a new thread or process...

Update: with a significantly shorter string, threads actually become faster, with an optimum advantage at a length of around 100 to 10000 (for this particular code sample): 

          Rate   Forks Threads
Forks   67.1/s      --    -64%
Threads  189/s    181%      --

(v5.10.1, Ubuntu 8.04 (kernel 2.6.24), string length 100)


          Rate   Forks Threads
Forks   84.7/s      --    -44%
Threads  152/s     79%      --

(v5.12.0, SUSE 11.1 (kernel 2.6.27), string length 10000)

[download]

In reply to Re^8: while reading a file, transfer the same data to two different processes. by almut
in thread while reading a file, transfer the same data to two different processes. by avanta

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