Re: Non blocking IO during an AJAX request

On May 29, 2010, at 1:39 PM, Zundra Daniel wrote:

> I realize this is a Ruby mailing list but I have a Ruby/Rails question =
that
> seems to fall more on the Ruby side of the fence.  I have a library =
file
> that creates a named pipe and writes the results of ping to the pipe.  =
This
> method is called via a get AJAX request to kick off the process.
>=20
>  def self.run(address)
>    Fifo.open(PINGFIFO)
>=20
>    Thread.new  {
>      IO.popen "ping -c 10 localhost" do |f|
>        until f.eof?
>          Fifo.write(f.gets, PINGFIFO)
>        end
>      end
>    }
>    end
>=20
> The problem is the 2nd AJAX request simply hangs indefinitely.  If I =
tail
> the pipe I can see data being written to it.  Does anyone have any =
insight
> into why this is happening?  It seemed like a simple enough problem =
but this
> one is throwing me for a loop (har!).


My first thought is buffering. I'm not sure what the semantics of =
Fifo.open and Fifo.write are in your code since 'Fifo' isn't a standard =
Ruby class. It also seems strange that you are calling Fifo.open but not =
capturing a return value to be used anywhere. Perhaps you need to call =
flush somewhere after Fifo.write to ensure the data is actually written =
to the fifo?  That might explain why your send request is blocking since =
the data isn't in the fifo yet.

Gary Wright=