From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from [87.239.111.99] (localhost [127.0.0.1]) by dev.tarantool.org (Postfix) with ESMTP id 4EC446EC55; Thu, 17 Jun 2021 18:49:43 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org 4EC446EC55 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tarantool.org; s=dev; t=1623944983; bh=CF1zUXtI4XKlfUylUUtAW2w1mth7hMO8fGOXDpqinRU=; h=To:Date:In-Reply-To:References:Subject:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=VmwevJo+brSstRM9rZueMwuO2Riesye6skF6i1s+fAazQi/MB5qZ+aR9EhfTlLXIw s+j4hKXJOZ28oENoKm1zaW5hBmbAS6XcgIX53cSYyqnlZlxH9Bvfo08xz/qmCaWbwT IgJbNEq2FxI77v/gXoocuNxNnhRUQJSXuDqn1Zy8= Received: from mail-lf1-f44.google.com (mail-lf1-f44.google.com [209.85.167.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 0E8E36EC57 for ; Thu, 17 Jun 2021 18:49:04 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org 0E8E36EC57 Received: by mail-lf1-f44.google.com with SMTP id x24so11271147lfr.10 for ; Thu, 17 Jun 2021 08:49:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=pGEWzk3VJ/4VrMMkCQZgTiriFiE20i1d2m8sDmzosDM=; b=aEjyny6ExndAlbQD1UvqSiuS2HLXlxvWNXSZPgXKdVg1v0rGEW0txNUrHvyGoNOIeH JGonzahmljKNAiIlpnIZ6oHTv4+HPd9rO4uzWgJsqM3rPn45qVrSWRb5e7ljgMBlyg85 ESQmT2kft9rk2vagGj2zngtXaLQJisdGhsCts0EFQWMGsw/M48VA9Pf1XZW9v/pLpSl5 UWlhpEmaB/vTWCSNzE8zFffZQbJSw3gZfquSWbb0oeOfae0I5vq0iEY5ZXcC637/0cW5 6I5V18xr0cwLtf1VT40N9ryVZqn02YYluecaR3vuBP/Meb19N1XrT7rZEeZH2hC3qx/N F6eA== X-Gm-Message-State: AOAM530WEWZVz12CImAj9KTzMdbrZ9nDVAt2iWsZsQWc+S4pCIBRwSWH QtyZFJFLswGexDxCr08ATQV8AxebPe0= X-Google-Smtp-Source: ABdhPJy1xEe43GguQAMkUq8SVlcslGPSH7FgmBvYmhMqomMBKo73H6Kbl8r6ALpCsGjGTY1VVw3dYw== X-Received: by 2002:a05:6512:1290:: with SMTP id u16mr4822107lfs.144.1623944942700; Thu, 17 Jun 2021 08:49:02 -0700 (PDT) Received: from grain.localdomain ([5.18.171.94]) by smtp.gmail.com with ESMTPSA id v26sm674756lfp.0.2021.06.17.08.49.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Jun 2021 08:49:01 -0700 (PDT) Received: by grain.localdomain (Postfix, from userid 1000) id 210FC5A0041; Thu, 17 Jun 2021 18:48:37 +0300 (MSK) To: tml Date: Thu, 17 Jun 2021 18:48:35 +0300 Message-Id: <20210617154835.315576-3-gorcunov@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210617154835.315576-1-gorcunov@gmail.com> References: <20210617154835.315576-1-gorcunov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v9 2/2] relay: provide information about downstream lag X-BeenThere: tarantool-patches@dev.tarantool.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Cyrill Gorcunov via Tarantool-patches Reply-To: Cyrill Gorcunov Cc: Vladislav Shpilevoy Errors-To: tarantool-patches-bounces@dev.tarantool.org Sender: "Tarantool-patches" We already have `box.replication.upstream.lag` entry for monitoring sake. Same time in synchronous replication timeouts are key properties for quorum gathering procedure. Thus we would like to know how long it took of a transaction to traverse `initiator WAL -> network -> remote applier -> initiator ACK reception` path. Typical output is | tarantool> box.info.replication[2].downstream | --- | - status: follow | idle: 0.61753897101153 | vclock: {1: 147} | lag: 0 | ... | tarantool> box.space.sync:insert{69} | --- | - [69] | ... | | tarantool> box.info.replication[2].downstream | --- | - status: follow | idle: 0.75324084801832 | vclock: {1: 151} | lag: 0.0011014938354492 | ... Closes #5447 Signed-off-by: Cyrill Gorcunov @TarantoolBot document Title: Add `box.info.replication[n].downstream.lag` entry `replication[n].downstream.lag` represents a lag between the main node writes a certain transaction to it's own WAL and a moment it receives an ack for this transaction from a replica. --- .../unreleased/gh-5447-downstream-lag.md | 6 + src/box/lua/info.c | 3 + src/box/relay.cc | 94 ++++++++++++- src/box/relay.h | 6 + .../replication/gh-5447-downstream-lag.result | 128 ++++++++++++++++++ .../gh-5447-downstream-lag.test.lua | 57 ++++++++ 6 files changed, 290 insertions(+), 4 deletions(-) create mode 100644 changelogs/unreleased/gh-5447-downstream-lag.md create mode 100644 test/replication/gh-5447-downstream-lag.result create mode 100644 test/replication/gh-5447-downstream-lag.test.lua diff --git a/changelogs/unreleased/gh-5447-downstream-lag.md b/changelogs/unreleased/gh-5447-downstream-lag.md new file mode 100644 index 000000000..f937ce35e --- /dev/null +++ b/changelogs/unreleased/gh-5447-downstream-lag.md @@ -0,0 +1,6 @@ +#feature/replication + + * Introduced `box.info.replication[n].downstream.lag` field to monitor + state of replication. This member represents a lag between the main + node writes a certain transaction to it's own WAL and a moment it + receives an ack for this transaction from a replica (gh-5447). diff --git a/src/box/lua/info.c b/src/box/lua/info.c index 0eb48b823..f201b25e3 100644 --- a/src/box/lua/info.c +++ b/src/box/lua/info.c @@ -143,6 +143,9 @@ lbox_pushrelay(lua_State *L, struct relay *relay) lua_pushnumber(L, ev_monotonic_now(loop()) - relay_last_row_time(relay)); lua_settable(L, -3); + lua_pushstring(L, "lag"); + lua_pushnumber(L, relay_txn_lag(relay)); + lua_settable(L, -3); break; case RELAY_STOPPED: { diff --git a/src/box/relay.cc b/src/box/relay.cc index b1571b361..ed6dd193d 100644 --- a/src/box/relay.cc +++ b/src/box/relay.cc @@ -70,6 +70,18 @@ struct relay_status_msg { struct vclock vclock; }; +/** + * Cbus message to update relay reader fiber status in tx thread. + */ +struct relay_reader_msg { + /** Parent */ + struct cmsg msg; + /** Relay instance */ + struct relay *relay; + /** Transaction lag value. */ + double txn_lag; +}; + /** * Cbus message to update replica gc state in tx thread. */ @@ -151,6 +163,8 @@ struct relay { struct cpipe relay_pipe; /** Status message */ struct relay_status_msg status_msg; + /** Reader fiber message */ + struct relay_reader_msg reader_msg; /** * List of garbage collection messages awaiting * confirmation from the replica. @@ -158,6 +172,11 @@ struct relay { struct stailq pending_gc; /** Time when last row was sent to peer. */ double last_row_time; + /** + * Last timestamp observed from remote node to + * compute @a tx.txn_lag value. + */ + double txn_acked_tm; /** Relay sync state. */ enum relay_state state; @@ -166,6 +185,14 @@ struct relay { alignas(CACHELINE_SIZE) /** Known relay vclock. */ struct vclock vclock; + /** + * A time difference between the moment when we + * wrote a transaction to the local WAL and when + * this transaction has been replicated to remote + * node (ie written to node's WAL) so that ACK get + * received. + */ + double txn_lag; /** * True if the relay needs Raft updates. It can live fine * without sending Raft updates, if it is a relay to an @@ -217,6 +244,12 @@ relay_last_row_time(const struct relay *relay) return relay->last_row_time; } +double +relay_txn_lag(const struct relay *relay) +{ + return relay->tx.txn_lag; +} + static void relay_send(struct relay *relay, struct xrow_header *packet); static void @@ -284,6 +317,15 @@ relay_start(struct relay *relay, int fd, uint64_t sync, relay->state = RELAY_FOLLOW; relay->row_count = 0; relay->last_row_time = ev_monotonic_now(loop()); + /* + * We assume that previously written rows in WAL + * are older than current node real time which allows + * to simplify @a tx.txn_lag calculation. In worst + * scenario when runtime has been adjusted backwards + * between restart we simply get some big value in + * @a tx.txn_lag until next transaction get replicated. + */ + relay->txn_acked_tm = ev_now(loop()); } void @@ -336,6 +378,12 @@ relay_stop(struct relay *relay) * upon cord_create(). */ relay->cord.id = 0; + /* + * If relay is stopped then lag statistics should + * be updated on next new ACK packets obtained. + */ + relay->txn_acked_tm = 0; + relay->tx.txn_lag = 0; } void @@ -466,11 +514,10 @@ relay_final_join(int fd, uint64_t sync, struct vclock *start_vclock, } /** - * The message which updated tx thread with a new vclock has returned back - * to the relay. + * The message which updated tx thread returns to the relay thread. */ static void -relay_status_update(struct cmsg *msg) +tx_update_complete(struct cmsg *msg) { msg->route = NULL; } @@ -500,7 +547,7 @@ tx_status_update(struct cmsg *msg) trigger_run(&replicaset.on_ack, &ack); static const struct cmsg_hop route[] = { - {relay_status_update, NULL} + {tx_update_complete, NULL} }; cmsg_init(msg, route); cpipe_push(&status->relay->relay_pipe, msg); @@ -607,6 +654,20 @@ relay_process_wal_event(struct wal_watcher *watcher, unsigned events) } } +static void +tx_reader_update(struct cmsg *msg) +{ + struct relay_reader_msg *rmsg = (struct relay_reader_msg *)msg; + rmsg->relay->tx.txn_lag = rmsg->txn_lag; + + static const struct cmsg_hop route[] = { + {tx_update_complete, NULL} + }; + + cmsg_init(msg, route); + cpipe_push(&rmsg->relay->relay_pipe, msg); +} + /* * Relay reader fiber function. * Read xrow encoded vclocks sent by the replica. @@ -616,6 +677,7 @@ relay_reader_f(va_list ap) { struct relay *relay = va_arg(ap, struct relay *); struct fiber *relay_f = va_arg(ap, struct fiber *); + struct relay_reader_msg *rmsg = &relay->reader_msg; struct ibuf ibuf; struct ev_io io; @@ -629,6 +691,30 @@ relay_reader_f(va_list ap) /* vclock is followed while decoding, zeroing it. */ vclock_create(&relay->recv_vclock); xrow_decode_vclock_xc(&xrow, &relay->recv_vclock); + /* + * Replica send us last replicated transaction + * timestamp which is needed for relay lag + * monitoring. Note that this transaction has + * been written to WAL with our current realtime + * clock value, thus when it get reported back we + * can compute time spent regardless of the clock + * value on remote replica. Since the communication + * goes between thread make sure the previous update + * to TX is complete. + */ + if (relay->txn_acked_tm < xrow.tm && + rmsg->msg.route == NULL) { + relay->txn_acked_tm = xrow.tm; + + static const struct cmsg_hop route[] = { + {tx_reader_update, NULL} + }; + + cmsg_init(&rmsg->msg, route); + rmsg->txn_lag = ev_now(loop()) - xrow.tm; + rmsg->relay = relay; + cpipe_push(&relay->tx_pipe, &rmsg->msg); + } fiber_cond_signal(&relay->reader_cond); } } catch (Exception *e) { diff --git a/src/box/relay.h b/src/box/relay.h index b32e2ea2a..615ffb75d 100644 --- a/src/box/relay.h +++ b/src/box/relay.h @@ -93,6 +93,12 @@ relay_vclock(const struct relay *relay); double relay_last_row_time(const struct relay *relay); +/** + * Returns relay's transaction's lag. + */ +double +relay_txn_lag(const struct relay *relay); + /** * Send a Raft update request to the relay channel. It is not * guaranteed that it will be delivered. The connection may break. diff --git a/test/replication/gh-5447-downstream-lag.result b/test/replication/gh-5447-downstream-lag.result new file mode 100644 index 000000000..2cc020451 --- /dev/null +++ b/test/replication/gh-5447-downstream-lag.result @@ -0,0 +1,128 @@ +-- test-run result file version 2 +-- +-- gh-5447: Test for box.info.replication[n].downstream.lag. +-- We need to be sure that slow ACKs delivery might be +-- caught by monitoring tools. +-- + +fiber = require('fiber') + | --- + | ... +test_run = require('test_run').new() + | --- + | ... +engine = test_run:get_cfg('engine') + | --- + | ... + +box.schema.user.grant('guest', 'replication') + | --- + | ... + +test_run:cmd('create server replica with rpl_master=default, \ + script="replication/replica.lua"') + | --- + | - true + | ... +test_run:cmd('start server replica') + | --- + | - true + | ... + +replica_id = test_run:get_server_id('replica') + | --- + | ... + +-- +-- Upon replica startup there is no ACKs to process. +assert(box.info.replication[replica_id].downstream.lag == 0) + | --- + | - true + | ... + +s = box.schema.space.create('test', {engine = engine}) + | --- + | ... +_ = s:create_index('pk') + | --- + | ... + +-- +-- The replica should wait some time before writing data +-- to the WAL, otherwise we might not even notice the lag +-- if media is too fast. Before disabling WAL we need to +-- wait the space get propagated. +test_run:switch('replica') + | --- + | - true + | ... +test_run:wait_lsn('replica', 'default') + | --- + | ... +box.error.injection.set("ERRINJ_WAL_DELAY", true) + | --- + | - ok + | ... + +-- +-- Insert a record and wakeup replica's WAL to process data. +test_run:switch('default') + | --- + | - true + | ... +lsn = box.info.lsn + | --- + | ... +box.space.test:insert({1}) + | --- + | - [1] + | ... +test_run:wait_cond(function() return box.info.lsn > lsn end) + | --- + | - true + | ... +-- The record is written on the master node. +test_run:switch('replica') + | --- + | - true + | ... +box.error.injection.set("ERRINJ_WAL_DELAY", false) + | --- + | - ok + | ... + +-- +-- Wait the record to be ACKed, the lag value should be nonzero. +test_run:switch('default') + | --- + | - true + | ... +test_run:wait_lsn('replica', 'default') + | --- + | ... +assert(box.info.replication[replica_id].downstream.lag > 0) + | --- + | - true + | ... + +-- +-- Cleanup everything. +test_run:switch('default') + | --- + | - true + | ... +box.schema.user.revoke('guest', 'replication') + | --- + | ... +test_run:cmd('stop server replica') + | --- + | - true + | ... +test_run:cmd('cleanup server replica') + | --- + | - true + | ... +test_run:cmd('delete server replica') + | --- + | - true + | ... diff --git a/test/replication/gh-5447-downstream-lag.test.lua b/test/replication/gh-5447-downstream-lag.test.lua new file mode 100644 index 000000000..3096e2ac3 --- /dev/null +++ b/test/replication/gh-5447-downstream-lag.test.lua @@ -0,0 +1,57 @@ +-- +-- gh-5447: Test for box.info.replication[n].downstream.lag. +-- We need to be sure that slow ACKs delivery might be +-- caught by monitoring tools. +-- + +fiber = require('fiber') +test_run = require('test_run').new() +engine = test_run:get_cfg('engine') + +box.schema.user.grant('guest', 'replication') + +test_run:cmd('create server replica with rpl_master=default, \ + script="replication/replica.lua"') +test_run:cmd('start server replica') + +replica_id = test_run:get_server_id('replica') + +-- +-- Upon replica startup there is no ACKs to process. +assert(box.info.replication[replica_id].downstream.lag == 0) + +s = box.schema.space.create('test', {engine = engine}) +_ = s:create_index('pk') + +-- +-- The replica should wait some time before writing data +-- to the WAL, otherwise we might not even notice the lag +-- if media is too fast. Before disabling WAL we need to +-- wait the space get propagated. +test_run:switch('replica') +test_run:wait_lsn('replica', 'default') +box.error.injection.set("ERRINJ_WAL_DELAY", true) + +-- +-- Insert a record and wakeup replica's WAL to process data. +test_run:switch('default') +lsn = box.info.lsn +box.space.test:insert({1}) +test_run:wait_cond(function() return box.info.lsn > lsn end) +-- The record is written on the master node. +test_run:switch('replica') +box.error.injection.set("ERRINJ_WAL_DELAY", false) + +-- +-- Wait the record to be ACKed, the lag value should be nonzero. +test_run:switch('default') +test_run:wait_lsn('replica', 'default') +assert(box.info.replication[replica_id].downstream.lag > 0) + +-- +-- Cleanup everything. +test_run:switch('default') +box.schema.user.revoke('guest', 'replication') +test_run:cmd('stop server replica') +test_run:cmd('cleanup server replica') +test_run:cmd('delete server replica') -- 2.31.1