--- libev/ev_kqueue.c	2012/02/12 08:39:38	1.53
+++ libev/ev_kqueue.c	2012/04/02 18:39:54	1.54
@@ -155,7 +155,8 @@
 int inline_size
 kqueue_init (EV_P_ int flags)
 {
-  /* Initialize the kernel queue */
+  /* initialize the kernel queue */
+  kqueue_fd_pid = getpid ();
   if ((backend_fd = kqueue ()) < 0)
     return 0;
 
@@ -185,8 +186,20 @@
 void inline_size
 kqueue_fork (EV_P)
 {
-  close (backend_fd);
+  /* some BSD kernels don't just destroy the kqueue itself,
+   * but also close the fd, which isn't documented, and
+   * impossible to support properly.
+   * we remember the pid of the kqueue call and only close
+   * the fd if the pid is still the same.
+   * this leaks fds on sane kernels, but BSD interfaces are
+   * notoriously buggy and rarely get fixed.
+   */
+  pid_t newpid = getpid ();
 
+  if (newpid == kqueue_fd_pid)
+    close (backend_fd);
+
+  kqueue_fd_pid = newpid;
   while ((backend_fd = kqueue ()) < 0)
     ev_syserr ("(libev) kqueue");