--- a/net/server_epoll.lua	Sun Oct 07 03:48:13 2018 +0200
+++ b/net/server_epoll.lua	Sun Oct 07 17:40:13 2018 +0200
@@ -714,7 +714,7 @@
 				poll:del(fd);
 			end
 		elseif r ~= "timeout" then
-			log("debug", "epoll_wait error: %s", tostring(r));
+			log("debug", "epoll_wait error: %s[%d]", r, w);
 		end
 	until once or (quitting and next(fds) == nil);
 	return quitting;