I believe that what you have there will destroy $req when the execute sub exits. At that time, $req will go out of lexical scope, and the local $SIG{INT} will also go out of scope, so there will be no leftover references to $req and it will go away.

If you hadn't made $SIG{INT} local, $req would stay in scope until it was set to something else.

Here's a test program I wrote to confirm this.

#!/usr/bin/perl -w

use strict;

package TestObject;

sub new
{
  my $class = shift;
  my $self = {};
  bless $self,$class;
}

sub somesub
{
  my $self = shift;
  print "Called somesub\n";
}

sub DESTROY
{
  my $self = shift;
  print "DESTROY\n";
}

package main;

print "Entering execute\n";
&execute;
print "Execute completed\n";

sub execute
{
  my $req = TestObject->new
    or die "Couldn't create TestObject\n";
  print "Created TestObject\n";
  local $SIG{INT} = sub { $req->somesub };
  print "Set \$SIG{INT}\n";
  sleep(1);
  print "Done with execute\n";
}
[download]

It produces:

Entering execute
Created TestObject
Set $SIG{INT}
Done with execute
DESTROY
Execute completed
[download]

showing that the object is destroyed immediately after execute completes.

Update: Fix typo in shebang line.