sub somefunction{

# somehow incorporate an alarm or a loop
# to run a "return" or "goto END" 
.......
if ( $shared_flag ==1 ){ return }
#or
if( $shared_flag == 1 ){ goto END }
......
......

END:
}

##</code><code>##

sub somefunction{
  local $SIG{ALRM} = sub { goto END };
  alarm 10; # wait 10 seconds before interrupting 

  while (1){sleep}

END:
}