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From: tiemann@mcc-pp.UUCP (Michael Tiemann)
Newsgroups: net.emacs
Subject: Inferior process violates gnuemacs 1st ammendment?
Message-ID: <1508@mcc-pp.UUCP>
Date: Wed, 13-Aug-86 20:57:51 EDT
Article-I.D.: mcc-pp.1508
Posted: Wed Aug 13 20:57:51 1986
Date-Received: Thu, 14-Aug-86 08:23:34 EDT
Organization: MCC, Austin, TX
Lines: 54
Keywords: hot-shots, pipes, send-region, @$**&!

So we *know* we're talking the same language, here's some simple
gnuemacs lisp code:

(defun setup-process (a &rest b)
  (interactive)
  (setq cat (eval (cons 'start-process (append (list a a a) b))))
  )

(defun send-process-region () 
  (interactive)
  (send-region cat (point) (mark))
  )

(defun cat ()
  (interactive)
  (setup-process "cat")
  (switch-to-buffer "cat")
)

(defun x-cat ()
  (interactive)
  (kill-buffer "cat")
)

(global-set-key "\e$" 'send-process-region)

Here's the problem: we set up at "cat" process (copy input to output),
find a big file, set point and mark to be 1000 characters apart, and
they repeatedly type "ESC-$" . 

On our SUN-3 about the 4th "ESC-4" the error message "writing to process:
operation would block, cat" pops up. If we continue to type "ESC-$",
the error sometimes comes up, and sometimes does not. On our VAX
11/750 "running" (walking) BDS 4.2, there is no error message, but the
gnuemacs shows up as Idle in ps -ux. (A few ^G's wake it into
abortion-land).

Clues? Look in process.c for the error-causing routine
(send_process_1). The problem gets worse: if I want to send a 10k
region, not even one call will go through. The code looks easy, so
either
	(1) I understand nothing about pipes.
	(2) The authors of GNU understand nothing about pipes
	(3) Our friends at Berkely understands nothing about pipes.
And its not "cat"'s fault: I wrote a program that just says "hello"
and then proceedes to read (and only read) the keyboard. Same result.

It seems to me that if I want to write a zillion bytes to a pipe, and
somebody else wants to read it, that the OS should wake and sleep us
until those zillion bytes have zipped through the pipe. If this is an
incorrect interpretation, please tell me how to pretend this is
happening.

Michael "God I wish I had shared memory" Tiemann