Am 13.04.2011 15:08, schrieb A J Stiles:
Hi. I just want to make sure I understand this before doing something that
might break things spectacularly for our users and customers :)
We are using Asterisk 1.6.2.9 and my programming language of choice is Perl.
I want, when a call comes in on someone's DDI number (which the person who
dialled it can only possibly have obtained by dialling 1471 after we called
them), to be able to look up the caller's details from one of our databases
(where the number ought to be stored, because we already dialled it).
Now, this search is going to take some time; so I'd like for the AGI script to
fork a clone of itself, so the parent process can exit and the dialplan
continue on to ring the person's phone, while the database lookup is done in
the background (the script doesn't need to have any further contact with
Asterisk -- it will initiate any necessary future communication via other
channels).
Is this the sort of thing I need?
########## begin code snippet ##########
#!/usr/bin/perl -w
use strict;
use Asterisk::AGI;
my $AGI = new Asterisk::AGI;
my %params = $AGI->ReadParse();
$SIG{CHLD} = "IGNORE";
if (my $child_pid = fork) {
# This is executed in the parent process
exit;
}
elsif (defined $child_pid) {
# This is executed in the child process
close STDIN;
close STDOUT;
close STDERR;
# Load some more modules and do some stuff
# that will take a long time
exit;
}
else {
die "Could not fork: $!";
};
########## end code snippet ##########
Am I right in thinking I shouldn't have to worry about zombie processes,
because the parent exits before the child and the init in modern Linux
distros is smart enough to deal with orphaned processes itself?
It should work - I think. BUT I am not really sure what will happen, if
the child process exits. The child works with a copy of all asterisk
ressources given to it, when forking. So when the child dies, perhaps
asterisk will do a hangup or continues in the dialplan for this process.
I think, that could cause some unwanted results.
You should try to write a daemon process which handles the database
lookups or whataver while being totally independent of the atserisk
process. This is a little bit more overhead for the communication
between the astersk process (the call itself) and your lookup-daemon.
But it would be more stable - for my point of view.
-Thorsten-
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