From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 745E9287B3 for ; Wed, 1 Aug 2018 08:36:37 -0400 (EDT) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id l7eJRhOwQMz1 for ; Wed, 1 Aug 2018 08:36:37 -0400 (EDT) Received: from smtp57.i.mail.ru (smtp57.i.mail.ru [217.69.128.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTPS id 3132F287AF for ; Wed, 1 Aug 2018 08:36:37 -0400 (EDT) Subject: [tarantool-patches] Re: [PATCH 1/4] Fix races related to object outdating References: <18f2ede05fa4a77bf0bd2abb64c25df0e3c574d6.1532940401.git.avkhatskevich@tarantool.org> <4a8e9e20-561d-6896-ea8c-8517add2bc50@tarantool.org> <1eeb6917-0153-919d-de56-c21052ea42f9@tarantool.org> From: Vladislav Shpilevoy Message-ID: <39dccfbe-8d6a-ffe7-b841-efa0c5352697@tarantool.org> Date: Wed, 1 Aug 2018 15:36:34 +0300 MIME-Version: 1.0 In-Reply-To: <1eeb6917-0153-919d-de56-c21052ea42f9@tarantool.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: tarantool-patches-bounce@freelists.org Errors-to: tarantool-patches-bounce@freelists.org Reply-To: tarantool-patches@freelists.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: tarantool-patches List-subscribe: List-owner: List-post: List-archive: To: tarantool-patches@freelists.org, Alex Khatskevich Hi! Thanks for the patch! See 2 comments below. > diff --git a/vshard/router/init.lua b/vshard/router/init.lua > index 142ddb6..1a0ed2f 100644 > --- a/vshard/router/init.lua > +++ b/vshard/router/init.lua > @@ -88,15 +94,18 @@ local function bucket_discovery(bucket_id) > log.verbose("Discovering bucket %d", bucket_id) > local last_err = nil > local unreachable_uuid = nil > - for uuid, replicaset in pairs(M.replicasets) do > - local _, err = > - replicaset:callrw('vshard.storage.bucket_stat', {bucket_id}) > - if err == nil then > - bucket_set(bucket_id, replicaset) > - return replicaset > - elseif err.code ~= lerror.code.WRONG_BUCKET then > - last_err = err > - unreachable_uuid = uuid > + for uuid, _ in pairs(M.replicasets) do > + -- Handle reload/reconfigure. > + replicaset = M.replicasets[uuid] 1. Please, explain, how is it possible, that before this line M.replicasets[uuid] can become nil. You iterate here over M.replicasets and on the previous line in '_' you have stored replicaset. How can here 'replicaset' differ from '_'? It has nothing in common with 'reload/reconfigure' case since you always iterate over M.replicasets - the most actual list of replicasets. Maybe you thought that pairs() stores its first argument into a temporary variable but looks like it is not. I checked it with a simple test: a = {} a.objs = {1, 2, 3, 4, 5} for k, v in pairs(a.objs) do print(a.objs[k]) if k == 2 then a.objs = {6, 7, 8, 9, 10} end end Output: 1 2 8 9 10 --- ... > + if replicaset then > + local _, err = > + replicaset:callrw('vshard.storage.bucket_stat', {bucket_id}) > + if err == nil then > + return bucket_set(bucket_id, replicaset.uuid) > + elseif err.code ~= lerror.code.WRONG_BUCKET then > + last_err = err > + unreachable_uuid = uuid > + end > end > end > local err = nil > @@ -513,27 +522,28 @@ local function router_cfg(cfg) > end > box.cfg(box_cfg) > log.info("Box has been configured") > - M.connection_outdate_delay = cfg.connection_outdate_delay > - M.total_bucket_count = total_bucket_count > - M.collect_lua_garbage = collect_lua_garbage > - M.current_cfg = new_cfg > -- Move connections from an old configuration to a new one. > -- It must be done with no yields to prevent usage both of not > -- fully moved old replicasets, and not fully built new ones. > - lreplicaset.rebind_replicasets(new_replicasets, M.replicasets, > - M.connection_outdate_delay) > - M.replicasets = new_replicasets > + lreplicaset.rebind_replicasets(new_replicasets, M.replicasets) > -- Now the new replicasets are fully built. Can establish > -- connections and yield. > for _, replicaset in pairs(new_replicasets) do > replicaset:connect_all() > end > + lreplicaset.wait_masters_connect(new_replicasets) > + lreplicaset.outdate_replicasets(M.replicasets, cfg.connection_outdate_delay) > + M.connection_outdate_delay = cfg.connection_outdate_delay > + M.total_bucket_count = total_bucket_count > + M.collect_lua_garbage = collect_lua_garbage > + M.current_cfg = cfg > + M.replicasets = new_replicasets > -- Update existing route map in-place. > - for bucket, rs in pairs(M.route_map) do > + local old_route_map = M.route_map > + M.route_map = {} > + for bucket, rs in pairs(old_route_map) do > M.route_map[bucket] = M.replicasets[rs.uuid] 2. Why do you need to save old_route_map into a separate variable? You can update M.route_map in place like it was done before. It is not? You fill the new route_map with exactly the same keys (maybe with different values, but it does not affect 'for' iteration). Moreover, when you create a new route_map instead of resetting the old, you double the memory. For huge bucket count it can be noticeable. > end > - > - lreplicaset.wait_masters_connect(new_replicasets) > if M.failover_fiber == nil then > lfiber.create(util.reloadable_fiber_f, M, 'failover_f', 'Failover') > end