RE: Not seeing anything back out of STDOUT

Thanks Rocco you are right.
I came across the solution myself last night after discovering all the
POE ASSERT settings.
Trawled the stats at the end - could see many POE::Wheel::Run "select
stdout" activities but nothing that was calling the StdOut Event
Handler.
So I removed the StdoutFilter and now I'm getting to see all the output
from the child process.
Now I just have to work out why POE::Filter::Reference was being
stalled.

Am I right in thinking that if the child sends anything on STDOUT that
isn't POE::Filter::Reference text then it stalls the comms for the
lifetime of that child process not just that instance of POE::Wheel::Run
"select stdout"??
If this is the case then I maybe have some untrapped output I need to
chase down. Which I guess I can do by leaving the filter off.

Simon


Simon Taylor
Development Team Lead NMS Applications
Network Managed Services
Nortel Networks

(e) [email protected]
(p) +44  1279 402291 ESN 6 742 2291
(m) +44 7740 533743 ESN 6 748 3743 
(yim) setuk_nortel

-----Original Message-----
From: Rocco Caputo [mailto:[email protected]] 
Sent: 09 November 2009 23:04
To: POE Mailing List
Subject: Re: Not seeing anything back out of STDOUT

This can happen with POE::Filter::Reference if the child process  
displays some non-POE::Filter::Reference text.  POE::Filter::Reference  
does its best to interpret the child process' output as legal data,  
and it patiently awaits the completion of a bad record.

The socket connection is made by creating the socket in the parent  
process, then sharing it between the parent and child after the fork()  
duplicates it.  No client/server shenanigans are performed to set up  
the connection.

It could be something else, but I can't tell without seeing more  
code. :)

-- 
Rocco Caputo - [email protected]


On Nov 9, 2009, at 06:05, Simon Taylor wrote:

> Using POE::Wheel::Run to create forked children.
>
> As soon as i fork them off I try and send some output back to the  
> parent
> but i never see it arrive.
>
> At this point STDOUT in the child is not a TTY and lsof indicates  
> its a
> socket connection.
>
>
>
> new_batch 30624 sdu 0u unix 0x00000100376a7680 9949033 socket
> new_batch 30624 sdu 1u unix 0x00000100376a7680 9949033 socket
> new_batch 30624 sdu 11u unix 0x00000100376a7680 9949033 socket
>
>
>
> I'm thinking this is possibly how POE is connecting the child output
> with that of the parent.
>
>
>
> I've run POE in Debug mode and im not seeing any calls into the Event
> Handler for STDOUT.
>
>
>
> Setup as follows - STDERR seems to be working ok.
>
> Any assistance appreciated.
>
>
>
>
>
> sub StartTasks {
>
> =Head3 _start
>
> Function called when POE wants to start tasks
>
> Shouldnt start any more than MAX_CONCURRENT_TASKS
>
> When it does it spawns children
>
> Event handlers allow information to be passed back to the parent  
> process
>
> Mapping between state and function is done in the object states line  
> in
> the POE::Session->create in _IterateChildrenParallel
>
>
>
> =cut
>
>  my ($kernel, $self, $heap) = @_[KERNEL, OBJECT];
>
>  my ($child, $task);
>
>  $self->{_logger}->debug("Enter/Reentry");
>
>  while (keys(%{$heap->{task}}) < MAX_CONCURRENT_TASKS) {
>
>      if (ref($self->{_children}) eq "ARRAY"){
>
>          $child = shift @{$self->{_children}};
>
>          last unless defined $child;
>
>          $self->{_logger}->debug("ARRAY "."Child = $child");
>
>          $task = POE::Wheel::Run->new(
>
>              Program      => sub {local *__ANON__ =
> "_StartTasksProgramSub";
>
>                                   $self->_CreateChild($child);
>
>                                   },
>
>              StdoutFilter => POE::Filter::Reference->new(),
>
>              StdoutEvent  => "TaskResult",
>
>              StderrEvent  => "TaskError",
>
>              CloseEvent   => "TaskDone",
>
>            );
>
>            $heap->{task}->{$task->ID} = $task;
>
>            $self->{_logger}->info("Created child Task/PID
> ".$task->ID."/".$task->PID);
>
>            $_[KERNEL]->sig_child($task->PID, 'sig_child');
>
>
>
>            # Wheel events include the wheel's ID.
>
>            $_[HEAP]{children_by_wid}{$task->ID} = $task;
>
>
>
>            # Signal events include the process ID.
>
>            $_[HEAP]{children_by_pid}{$task->PID} = $task;
>
>
>
>
>
>
>
>     } elsif (ref($self->{_children}) eq "HASH") {
>
>              $self->{_logger}->debug("HASH "."Child = $child");
>
>              $self->_CreateChild($child);
>
>     } else {
>
>              $self->{_logger}->debug("SCALAR "."Child = $child");
>
>              $self->_CreateChild($child);
>
>     } # If end
>
>  } # While end
>
> }
>
>
>
> sub TaskResult {
>
>  my ($self,$result) = @_[OBJECT, ARG0];
>
>  $self->{_logger}->info("ID/PID/Result ID: $result->{taskid} :
> $result->{pid} :$result->{status}\n");
>
>
>
>  my %sec_status = %{$result->{section_status}};
>
>
>
>  foreach my $key (%sec_status){
>
>    $self->{_logger}->info("$sec_status{$key}\n");
>
>  }
>
>
>
> }
>
>
>
>
>
> Simon Taylor
>
> Development Team Lead NMS Applications
>
> Network Managed Services
>
> Nortel Networks
>
>
>
> (e) [email protected]
>
> (p) +44  1279 402291 ESN 6 742 2291
>
> (m) +44 7740 533743 ESN 6 748 3743
>
> (yim) setuk_nortel
>
>
>