make sure we don't chew too much CPU when the outgoing fd is full

io.c

@@ -372,6 +372,7 @@ static void writefd_unbuffered(int fd,char *buf,int len)
 
 			if (ret == -1 && 
 			    (errno == EWOULDBLOCK || errno == EAGAIN)) {
+				msleep(1);
 				continue;
 			}
 
@@ -463,6 +464,17 @@ void io_end_buffering(int fd)
 	}
 }
 
+/* some OSes have a bug where an exit causes the pending writes on
+   a socket to be flushed. Do an explicit shutdown to try to prevent this */
+void io_shutdown(void)
+{
+	if (multiplex_out_fd != -1) close(multiplex_out_fd);
+	if (io_error_fd != -1) close(io_error_fd);
+	multiplex_out_fd = -1;
+	io_error_fd = -1;
+}
+
+
 static void writefd(int fd,char *buf,int len)
 {
 	stats.total_written += len;