Out of curiousity I tried testing these out and neither seem to work ?

use DBI;
use DBD::Oracle;

$dsn = "dbi:Oracle:MYSID";
$dbuser = "myuser/mypass";
my $dbh = DBI->connect($dsn, $dbuser, '', { AutoCommit => 1, PrintErro
+r => 0 });

unless($dbh) {
   die "Unable to connect ($DBI::errstr)\n";
   exit 1;
}

@procs{ @{ $dbh->selectall_arrayref( "select spid from v\$process" ) }
+ } = ();

my $xpid = 16405;
if ( exists $procs{ $xpid } ) {
      print "Pid in use : $xpid\n";
}
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The $xpid definitely exists in the v$process view. Is there something missing from this ?