Re: Not seeing anything back out of STDOUT

Yes, plain text looks like a very large data structure to  
POE::Filter::Reference.  It is busy buffering data until it has enough  
to thaw().  That behavior appears to the application as if the filter  
has stalled.

-- 
Rocco Caputo - [email protected]


On Nov 10, 2009, at 04:29, Simon Taylor wrote:

> 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
>>
>>
>>
>