non blocking pipe

[Spocchio]

Hi, i'm writing a gui tool, I need to open a non blocking pipe in read
mode, to avoid the block of the gui when the stream become slow..
Is it possible to open a non blocking pipe in read mode whitout using
threads or fork()?
I like simple things, i only need something return me undef is there
is no input,

$smwID = open( STREAM, $command . '|');
Glib::Timeout->add(100,
        sub {

               if($line = nonblocking_read(STREAM)
               {
                   # process the line only if the program send
something,
                   # if i use a blocking reading like $line=<STREAM> ;
                   # the entry gui will get blocked until the output
come
               }
        }
    );