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 0E05A6EC55; Fri, 7 May 2021 00:42:41 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org 0E05A6EC55 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tarantool.org; s=dev; t=1620337361; bh=Nu6fG1FMVaDsnG1Dt3MpTfZRPqkSefLPnQfwfR/VKJU=; 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=qa0m7IfYT5deD7FCcfMXIhtjxvIl5j9rH4YmwksGduDHxW5BO7wxgYft5mwgRRuDu hxwLteoBCLYp889cAwhe4IAo3QMKQljdOI50oS8XrEpI0I39KdoptjvbnxBZ6ZMZgw MFnrU57es24AgXXmoH1/vpPH5CQC6SShQdEYTyOA= Received: from mail-lj1-f177.google.com (mail-lj1-f177.google.com [209.85.208.177]) (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 471EC6EC56 for ; Fri, 7 May 2021 00:42:02 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 dev.tarantool.org 471EC6EC56 Received: by mail-lj1-f177.google.com with SMTP id b21so8935002ljf.11 for ; Thu, 06 May 2021 14:42:02 -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=QhelILd1CDUwXSyku8P5+00n+DBGuYNtzIlfX8r0s84=; b=eQ8bSRdjHdf9D6ABgkGV424vzBhpH+4Q/HEuVoEduXdA7c3YbmB6J1bvFrP/cV4LVk HL50P+mecoPDycEWauFS05WxTL5G1LzMIpxjfQIcVXwNzl5hrYrgRheDmUMalH4eD9C0 w0erW08zECKZ29BrtjoOUooSuRxnkBxTmf0kKYMrrWpTWfDSdutEgGUE2YmrBO5N1loN xOLcUKAcDHDNgfREhWBoAxur+9NSP3Wu7ySSef0VTInntdE2X1LtskIp985dV78F+Bcx aNjgvbVDKGQ8fhQ7iy3X+KPSTg/bNiz8QqfP6GSC0x4TUONAF3WSXuQCQ3e8QkTgCdn6 XeTA== X-Gm-Message-State: AOAM5335Z/GZZ+l97hoMzwzN+SdsdqnBWsfOJVlULnKJG82N+8YjRTDf XVR3bWgMGYw9lSlsKKDYDFL+9bvw09k= X-Google-Smtp-Source: ABdhPJwOL9fiW6BkzOh7s5CTNuXll9KFqS2JrA2ond/DVj4MnlHJ++apF7OEKoDfgltBz9w8Eptz9A== X-Received: by 2002:a2e:7c16:: with SMTP id x22mr5165103ljc.357.1620337321139; Thu, 06 May 2021 14:42:01 -0700 (PDT) Received: from grain.localdomain ([5.18.171.94]) by smtp.gmail.com with ESMTPSA id o5sm1272318ljj.103.2021.05.06.14.42.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 May 2021 14:42:00 -0700 (PDT) Received: by grain.localdomain (Postfix, from userid 1000) id EAD3F560213; Fri, 7 May 2021 00:41:33 +0300 (MSK) To: tml Date: Fri, 7 May 2021 00:41:32 +0300 Message-Id: <20210506214132.533913-3-gorcunov@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210506214132.533913-1-gorcunov@gmail.com> References: <20210506214132.533913-1-gorcunov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Tarantool-patches] [PATCH v4 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 -> ACK` path. Typical ouput 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` is the time difference between last transactions been written to the WAL journal of the transaction initiator and the transaction written to WAL on the `n` replica. In other words this is a lag in seconds between the main node writes data to own WAL and replica `n` get this data replicated to the own WAL journal. This value is not a constant and if there is no data to replicate (ie when nodes are sitting in idle cycle, or new heartbeat message obtained) then it get set back to zero. --- .../unreleased/gh-5447-downstream-lag.md | 6 ++ src/box/lua/info.c | 3 + src/box/relay.cc | 18 ++++ src/box/relay.h | 6 ++ .../replication/gh-5447-downstream-lag.result | 93 +++++++++++++++++++ .../gh-5447-downstream-lag.test.lua | 41 ++++++++ 6 files changed, 167 insertions(+) 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..3b11c50ee --- /dev/null +++ b/changelogs/unreleased/gh-5447-downstream-lag.md @@ -0,0 +1,6 @@ +#feature/replication + + * Introduce `box.info.replication[n].downstream.lag` to monitor state + of replication which is especially important for synchronous spaces + where malfunctioning replicas may prevent quorum from gathering votes + to commit a transaction. diff --git a/src/box/lua/info.c b/src/box/lua/info.c index 0eb48b823..5b7c25f28 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_lag(relay)); + lua_settable(L, -3); break; case RELAY_STOPPED: { diff --git a/src/box/relay.cc b/src/box/relay.cc index ff43c2fc7..1501e53c7 100644 --- a/src/box/relay.cc +++ b/src/box/relay.cc @@ -158,6 +158,12 @@ struct relay { struct stailq pending_gc; /** Time when last row was sent to peer. */ double last_row_time; + /** + * A time difference between moment when we + * wrote a row in the local WAL and received + * an ACK that peer has it replicated. + */ + double lag; /** Relay sync state. */ enum relay_state state; @@ -217,6 +223,12 @@ relay_last_row_time(const struct relay *relay) return relay->last_row_time; } +double +relay_lag(const struct relay *relay) +{ + return relay->lag; +} + static void relay_send(struct relay *relay, struct xrow_header *packet); static void @@ -621,6 +633,12 @@ 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); + if (xrow.tm != 0) { + double delta = ev_now(loop()) - xrow.tm; + relay->lag = delta; + } else { + relay->lag = 0; + } fiber_cond_signal(&relay->reader_cond); } } catch (Exception *e) { diff --git a/src/box/relay.h b/src/box/relay.h index b32e2ea2a..0f7d8d1bc 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 lag. + */ +double +relay_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..8586d0ed3 --- /dev/null +++ b/test/replication/gh-5447-downstream-lag.result @@ -0,0 +1,93 @@ +-- test-run result file version 2 +-- +-- gh-5447: Test for box.info.replication[n].downstream.lag. +-- We need to be sure that if replica start been back of +-- master node reports own lagging and cluster admin would +-- be able to detect such situation. +-- + +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 + | ... + +s = box.schema.space.create('test', {engine = engine}) + | --- + | ... +_ = s:create_index('pk') + | --- + | ... + +-- +-- The replica should wait some time (wal delay is 1 second +-- by default) so we would be able to detect the lag, since +-- on local instances the lag is minimal and usually transactions +-- are handled instantly. +test_run:switch('replica') + | --- + | - true + | ... +box.error.injection.set("ERRINJ_WAL_DELAY", true) + | --- + | - ok + | ... + +test_run:switch('default') + | --- + | - true + | ... +box.space.test:insert({1}) + | --- + | - [1] + | ... +test_run:wait_cond(function() return box.info.replication[2].downstream.lag ~= 0 end, 10) + | --- + | - true + | ... + +test_run:switch('replica') + | --- + | - true + | ... +box.error.injection.set("ERRINJ_WAL_DELAY", false) + | --- + | - ok + | ... +-- +-- Cleanup everything. +test_run:switch('default') + | --- + | - true + | ... + +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..650e8e215 --- /dev/null +++ b/test/replication/gh-5447-downstream-lag.test.lua @@ -0,0 +1,41 @@ +-- +-- gh-5447: Test for box.info.replication[n].downstream.lag. +-- We need to be sure that if replica start been back of +-- master node reports own lagging and cluster admin would +-- be able to detect such situation. +-- + +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') + +s = box.schema.space.create('test', {engine = engine}) +_ = s:create_index('pk') + +-- +-- The replica should wait some time (wal delay is 1 second +-- by default) so we would be able to detect the lag, since +-- on local instances the lag is minimal and usually transactions +-- are handled instantly. +test_run:switch('replica') +box.error.injection.set("ERRINJ_WAL_DELAY", true) + +test_run:switch('default') +box.space.test:insert({1}) +test_run:wait_cond(function() return box.info.replication[2].downstream.lag ~= 0 end, 10) + +test_run:switch('replica') +box.error.injection.set("ERRINJ_WAL_DELAY", false) +-- +-- Cleanup everything. +test_run:switch('default') + +test_run:cmd('stop server replica') +test_run:cmd('cleanup server replica') +test_run:cmd('delete server replica') -- 2.30.2