Re: busyloop in sigchld_handler

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

The following change (without a ChangeLog entry) made operations using
subprocesses really sluggish on Mac OS X.  Is it possible to restrict
the workaround to the relevant platforms?

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

===================================================================
RCS file: /sources/emacs/emacs/src/process.c,v
retrieving revision 1.505
retrieving revision 1.506
diff -c -r1.505 -r1.506
*** emacs/src/process.c	2007/03/20 08:51:03	1.505
--- emacs/src/process.c	2007/03/25 03:03:40	1.506
***************
*** 6501,6517 ****
  #define WUNTRACED 0
  #endif /* no WUNTRACED */
        /* Keep trying to get a status until we get a definitive result.  */
!       while (1)
! 	{
  	  errno = 0;
  	  pid = wait3 (&w, WNOHANG | WUNTRACED, 0);
- 	  if (! (pid < 0 && errno == EINTR))
- 	    break;
- 	  /* Avoid a busyloop: wait3 is a system call, so we do not want
- 	     to prevent the kernel from actually sending SIGCHLD to emacs
- 	     by asking for it all the time.  */
- 	  sleep (1);
  	}
  
        if (pid <= 0)
  	{
--- 6501,6517 ----
  #define WUNTRACED 0
  #endif /* no WUNTRACED */
        /* Keep trying to get a status until we get a definitive result.  */
!       do
!         {
! 	  /* For some reason, this sleep() prevents Emacs from sending
!              loadavg to 5-8(!) for ~10 seconds.
!              See http://thread.gmane.org/gmane.emacs.devel/67722 or
!              http://www.google.com/search?q=busyloop+in+sigchld_handler */
!           sleep (1);
  	  errno = 0;
  	  pid = wait3 (&w, WNOHANG | WUNTRACED, 0);
  	}
+       while (pid < 0 && errno == EINTR);
  
        if (pid <= 0)
  	{