Re: [bug-gawk] Problem with printing 5000 lines to a coprocess

[Andrew J. Schorr]

Hi,

On Mon, Dec 22, 2014 at 12:24:29PM -0200, Hermann Peifer wrote:
> On 2014-12-21 12:50, Andrew J. Schorr wrote:
> >
> >Hmmm.  The "pty" trick is just a way to solve the flushing problem.
> 
> Which is exactly the one I wanted to solve, as the flushing problem made my
> initial code (send 1 line, then read 1 result) either hang or terribly slow
> (after forcing the coprocess to flush its output via close().
> 
> Another "trick" would be to use a 2-way pipe and request line-buffering like
> this, as I learned from [0]:
> command = "stdbuf -o L " subprogram

Thanks for the tip; I was not familiar with the stdbuf program.  That's
a clever hack to use LD_PRELOAD to fix the buffering, and it should certainly
perform a bit better than using ptys, as you noted.  Of course, it depends
on the application's using stdio for its output.  In most cases, that's
an OK assumption.

I have almost always used coprocesses that I've written myself, and in such
cases, I add a command-line option to force line-buffering.

Regards,
Andy