Re: non blocking issue ?

`Zidane Tribal a écrit :
> On 28/05/2008, Isabelle Cabrera <isabelle.cabrera@inria.fr> wrote:
>   
>> Hi,
>>
>> I have a problem using the Event module.
>>
>> My goal: I have several sentences that I need to parse. For a faster
>> process, I have a dispatcher which sends the sentences to several hosts
>> so that the processes are distributed.
>>
>> In my dispatcher, I register every host. For each host I create a watcher :
>>
>>     $self->{hosts}{$host}{watcher} =
>>     Event->var(desc =>"Process sentence on $host",
>>            var  => \$client->{free},
>>            poll => 'w',
>>            cb   => $self->next_dag($host),
>>            debug => 4,
>>     );
>>
>> The callback next_dag is called every time all the process of parsing
>> the sentence and sending back the results is done (more precisely when
>> the host says it's ready to receive a new sentence, with variable
>> $client->{free}).
>>
>> Of course, I would like that every host can work at the same time
>> (that's the point...), but my problem is that they do the job
>> subsequently, one sentence at the time.
>>
>> The created event mainly does the following:
>> - get the next sentence from a file
>> - send this sentence to the parser on the free host (through a server of
>> parser accessed with Net::Telnet)
>> - get the result of the parsing (yes or no) (still through Net::Telnet...)
>> - if yes, connect again to the server of parser to generate one or
>> several outputs and write them into one or several files
>> - says "I'm ready to get a new sentence to parse", triggering the
>> variable 'free'
>>
>> I thought that creating an event was automatically non blocking and
>> several events could happen at the same time. Does the problem come from
>> the I/O interactions ? If so, do I need to separate all these stages and
>> watch for every I/O interactions ? And do I need to specify somewhere
>> that I want non blocking I/O ?
>>
>> Best regards,
>> Isabelle
>>
>> --
>> Isabelle Cabrera
>> Projet Alpage - INRIA Rocquencourt
>> http://alpage.inria.fr
>> Tel : 01 3963 5270
>>
>>
>>     
>
> it sounds like each event is blocking, waiting for the computation to
> return a result, and then releasing to allow EV to continue it's loop.
>  i have had a similar problem recently, (a multi-server irc bot), and
> found i have a similar problem, each time the event was blocking and
> waiting for a reply.
>
> how i solved it was to create a readable event for each socket, so
> rather than send-wait-receive as you have, its send, then assign a
> receive callback to trigger when a result is returned.   thus, send
> commands down each socket, and allow EV to loop until each one
> returns, and as each result is returned, send another query, then let
> EV wait on the result again, ad infinitum.
>
> i suspect this is a horribly confusing answer, and unfortunately i'm
> away from home for a few days so i cant provide a code example, but
> feel free to ask anything further.
>
> James Clark.
>   
Thank you James. Finally my problem comes from the fact that my I/O 
interactions are blocking. So instead of using Net::Telnet I'm trying to 
use IO::Socket to do non blocking I/O.
One other problem is that I had a huge callback, so I'm going to split 
up my code in smaller peaces.

Best regards,
Isabelle Cabrera

-- 
Isabelle Cabrera
Equipe-Projet Alpage - INRIA Paris-Rocquencourt
http://alpage.inria.fr
Tel : 01 3963 5270

• non blocking issue ? by Isabelle Cabrera
• Re: non blocking issue ? by `Zidane Tribal
• Re: non blocking issue ? by Isabelle Cabrera