The part relevant to implementing timing out and interrupting a mysql query can be condensed to:

use strict;
...
use warnings;
use DBI;
use Sys::SigAction;
...
        my $sth_o=$dbh_o->prepare($SQL_s);
        my $rows_s;
        eval { # Time out and interrupt work
            my $TimeOut=Sys::SigAction::set_sig_handler('ALRM',sub {
                $dbh_o->clone()->do("KILL QUERY ".$dbh_o->{"mysql_thre
+ad_id"});
                die "Timed Out!";
                 });
            local $SIG{INT}=sub {
                $dbh_o->clone()->do("KILL QUERY ".$dbh_o->{"mysql_thre
+ad_id"});
                die "Ctrl-C'd!";
                 };
            # Set alarm
            alarm(<max time allowed>);
            $rows_s=$sth_o->execute(@Argument_a);
            # Clear alarm
            alarm(0);
             };
        # Prevent race condition
        alarm(0);
        die
            if $@;
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My attempts to use a local $SIG{ALRM} in place of the Sys::SigAction::set_sig_handler weren't successful. I'll freely admit to not trying too hard as Sys::SigAction::set_sig_handler works fine.