Tom Allison am Dienstag, 22. November 2005 20.59:
> John Doe wrote:
> > Tom Allison am Dienstag, 22. November 2005 12.24:
> >>I figured out I can do this:
> >>
> >>eval {
> >> local $SIG{ALRM} = sub { warn("alarm\n") };
> >> alarm 1;
> >> for(my $j = 0; $j < 1_000_000, $j++) {
> >> my $x = log(rand()*1000+1);
> >> }
> >> alarm 0;
> >>};
> >>if ( $@ ) {
> >> carp "[EMAIL PROTECTED]";
> >>}
> >>
> >>Which is very similar to the man pages.
> >>But there are a few inconsistencies I'm trying to sort out.
> >
> > The syntax is incorrect, see the comma in the for-().
>
> I didn't copy it correctly, you are right about the syntax.
> I also changed the warn to die.
> I can get this to work in my test script.
Hi Tom
I must admit that I'm not an all-day user of sigs. That might be one of the
reasons that I can't give you the answer, and there will be one from one of
the gurus here I guess.
> Now, I've replaced the 'for(my $j = 0....}' loop with the real deal and
> it's just not working at all.
What's the replacement? Fairly the big deal from below (it's not a loop).
What are the errors?
> The real deal is more like this (I'm not posting all the code because it
> might be boring)
>
> eval {
> local $SIG{ALRM} = sub { die "alarm\n" };
> alarm 60;
> my $ref = fetchdata($sql, $db);
> alarm 0'
> };
> ....
>
> and fetchdata() is a function in a module.
> This function is basically a wrapper around DBI:
>
> sub fetchdata {
> my ($sql, $db) = @_;
> my $dbh = get_dbh($db) or die $@; # another function within this
> module
> my $ref = $dbh->fetchall_arrayref($sql) or die $@;
> return $ref;
> }
>
> ----
>
> I didn't write everything here perfectly so if there are syntax erros
> please forgive me. But I'm not sure how these ALRM signals behave with
> all these subroutine calls.
In the example above, the alarm will trigger die and the program control gets
back to the code after the eval{}; the subs get interrupted, but I don't know
the gory details about the exact interruption point etc.
> I get one 'alarm' and then nothing, the sql runs for a long time. I'm
> intentially trying to test it to make sure it will 'alarm' more than
> once..
Not quite shure what you mean.
[Could it be that your system's signal handlers get lost between invocations?]
> The problem is the database server gets overloaded so I want to
> try, wait, try, wait, try, die with each wait period being on the order
> of an hour. It would be convenient to do this if I could.
Sounds like much, one hour! I'm not experienced with big databases, but is
there no possibility to tune the server a bit? How can it be useful with
waiting periods up to 1 hour?
> The alternative would be to run two shell scripts. The first to create
> a pidfile and the second to run only if that pidfile exists. Successful
> completion of the program would remove the pidfile.
>
> But that's not as 'cool' or very perl-ish. I was hoping to be able to
> use the alarm.
One of the gurus surely has an IPC or whatever solution :-)
Sorry for not providing more help.
joe
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