Hi,
just checking one more time: is anyone looking after PoCo::Child, or is
it orphaned?
TIA,
Tony.
On Wed, 15 Apr 2009, Tony Wildish wrote:
> Hi,
>
> I sent this to the bug-poe-component-ch...@rt.cpan.org list some time ago
> but it looks like that list is dead. Is there someone here managing
> PoCo::Child?
>
> Cheers,
> Tony.
>
> ---------- Forwarded message ----------
> Date: Tue, 24 Mar 2009 12:56:33 +0100 (CET)
> From: Tony Wildish <wild...@mail.cern.ch>
> To: bug-poe-component-ch...@rt.cpan.org
> Subject: Bug in PoCo::Child when PID wraps round
>
> Hi,
>
> we have been using PoCo::Child in a project for a while now and have just
> uncovered a bug. The internal bookkeeping for the association of wheelIDs
> and PIDs is wrong, with the result that when the OS PID wraps round, the
> wrong wheelID will be given to the 'done' event.
>
> I'm using PoCo::Child version 1.39, perl 5.8.5, kernel
> 2.6.9-78.0.8.EL.cernsmp.
>
> You can see the bug by inspection of the code. At line 192 we have:
>
> my $id = $wheel->ID;
> $self->debug(qq/run(): "@$cmd", wheel=$id, pid=/ . $wheel->PID);
>
> $self->{$PKG}{pids}{$wheel->PID} = $id;
>
> so the {pids} are inserted keyed on $wheel->PID. But at line 268, the
> clean up deletes as follows:
>
> delete $self->{$PKG}{wheels}{$id};
> delete $self->{$PKG}{pids}{$id};
>
> so it's deleting keyed on wheel->ID, not $wheel->PID.
>
> When the PIDs wrap round, the protection in sig_child is broken by this:
>
> sub sig_child {
> my ($kernel, $self, $pid, $rc) = @_[KERNEL, OBJECT, ARG1, ARG2];
>
> my $id = $self->{$PKG}{pids}{$pid} || "";
>
> # child death signals are issued by the OS and sent to all
> # sessions; we want to handle only our own children
>
> return unless $id;
>
> Because the {pids} hash had the wrong entry deleted in the cleanup, when
> the PIDs wrap, an old $id will be found where none should be. So sig_child
> will not return here, and will cause 'done' to be fired with the old
> wheelID, which is plainly wrong.
>
> Also, the cleanup around line 268/269 should remove {CLOSED} and
> {SIGCHLD} entries for the wheel too. That's less serious because it won't
> cause a problem until wheel-IDs wrap round, which will take a lot longer,
> but it's still a leak.
>
> Cheers,
> Tony.
>
