On 5/15/06, Tom Allison <[EMAIL PROTECTED]> wrote:
my $pid = fork();
print "$pid --> $file\n";
Because your process table can become full and temporarily prevent
forking new processes, you should check the return value of fork
whenever you're making more than N processes. The value of N depends
upon a number of factors, so I generally assume N=0. Most of the time,
I just call this safe_fork routine in place of fork, since this
handles the retries for me automatically.
sub safe_fork () {
use Errno;
my $retries = 10;
while ($retries--) {
my $rv = fork;
return $rv if defined $rv; # it worked
return unless $retries;
return unless $!{EAGAIN};
sleep 3;
}
die "Well, how did I get here?";
}
I will get an output of:
0 --> file_one
3242 --> file_one
0--> file_two
but no 3243-->file_two.
If that output is coming from several concurrent processes, any one
process's output can "interrupt" another: The data may be interleaved
in confusing ways. But maybe you simply couldn't fork another process?
How many processes were you starting at once?
Unfortunately, perl -d doesn't work well for forks.
There's actually some support for fork in the debugger, but I'm having
a hard time finding any documentation on it, other than the comments.
Search for 'fork' in your perl5db.pl file, if you need it.
Good luck with it!
--Tom Phoenix
Stonehenge Perl Training
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