The problem is the order in which the handle's destructor and the END block are executed. If the file handle is destroyed first, you have a problem. When destroying a file handle, perl closes it, and closing a file handle opened with open '...|' causes perl to wait until the child process exits. Seeing as the kill command hasn't been executed, that won't happen.

You don't have that problem with open3 since you control when waitpid is called.

use IPC::Open3 qw( open3 );

my @tail_pids;

END {
   for my $tail_pid (@tail_pids) {
      kill TERM => $tail_pid;
      waitpid($tail_pid, 0);
   }
}

sub start_tail {
   my ($mw, $file) = @_;

   my ($from_tail, $tail_err);
   push @tail_pids, open3(undef, $from_tail, $tail_err, qw( tail -1lf 
+), $file);

   $mw->fileevent($from_tail, 'readable' => [ \&input_from_tail, $mw, 
+$file ]);
   $mw->fileevent($tail_err,  'readable' => [ \&sink,            $mw, 
+$file ]);
}
[download]

Notes:

• Placing END in start_tail won't work.
• You need a simple sink function that simply reads and discards the data waiting in the file handle.
• It now handles file names containing special characters.
• It doesn't handle SIGPIPE from tail ending prematurely.
• Untested.

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