[Emacs-diffs] /srv/bzr/emacs/trunk r111132: Avoid busy-waiting for child processes on Windows. (Bug#13086)

[Eli Zaretskii]

------------------------------------------------------------
revno: 111132
fixes bug: http://debbugs.gnu.org/13086
committer: Eli Zaretskii <address@hidden>
branch nick: trunk
timestamp: Thu 2012-12-06 20:36:22 +0200
message:
  Avoid busy-waiting for child processes on Windows.  (Bug#13086)
  
   src/w32proc.c (waitpid): Avoid busy-waiting when called with WNOHANG
   if the child process is still running.  Instead, exit the wait
   loop and return zero.
modified:
  src/ChangeLog
  src/w32proc.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2012-12-06 13:48:11 +0000
+++ b/src/ChangeLog     2012-12-06 18:36:22 +0000
@@ -1,3 +1,9 @@
+2012-12-06  Eli Zaretskii  <address@hidden>
+
+       * w32proc.c (waitpid): Avoid busy-waiting when called with WNOHANG
+       if the child process is still running.  Instead, exit the wait
+       loop and return zero.  (Bug#13086)
+
 2012-12-06  Dmitry Antipov  <address@hidden>
 
        * frame.h (x_char_width, x_char_height): Remove prototypes.

=== modified file 'src/w32proc.c'
--- a/src/w32proc.c     2012-12-03 21:42:12 +0000
+++ b/src/w32proc.c     2012-12-06 18:36:22 +0000
@@ -1220,13 +1220,22 @@
     {
       QUIT;
       active = WaitForMultipleObjects (nh, wait_hnd, FALSE, timeout_ms);
-    } while (active == WAIT_TIMEOUT);
+    } while (active == WAIT_TIMEOUT && !dont_wait);
 
   if (active == WAIT_FAILED)
     {
       errno = EBADF;
       return -1;
     }
+  else if (active == WAIT_TIMEOUT && dont_wait)
+    {
+      /* PID specifies our subprocess, but it didn't exit yet, so its
+        status is not yet available.  */
+#ifdef FULL_DEBUG
+      DebPrint (("Wait: PID %d not reap yet\n", cp->pid));
+#endif
+      return 0;
+    }
   else if (active >= WAIT_OBJECT_0
           && active < WAIT_OBJECT_0+MAXIMUM_WAIT_OBJECTS)
     {