Orchestrator源码解读2-故障失败发现

目录

前言

核心流程函数调用路径

GetReplicationAnalysis

故障类型和对应的处理函数

与MHA相比

前言

Orchestrator另外一个重要的功能是监控集群，发现故障。根据从复制拓扑本身获得的信息，它可以识别各种故障场景。Orchestrator介绍四-失败/故障检测_orchestrator 心跳-CSDN博客

核心流程函数调用路径

ContinuousDiscovery
--> CheckAndRecover // 检查恢复的入口函数
--> GetReplicationAnalysis  // 查询SQL，根据实例的状态确定故障或者警告类型。检查复制问题  (dead master; unreachable master; 等)
--> executeCheckAndRecoverFunction  // 根据分析结果选择正确的检查和恢复函数。然后会同步执行该函数。
--> getCheckAndRecoverFunction // 根据分析结果选择正确的检查和恢复函数。然后会同步执行该函数。
--> runEmergentOperations // 
--> checkAndExecuteFailureDetectionProcesses //   尝试往数据库中插入这个故障发现记录，然后执行故障发现阶段所需的操作，执行 OnFailureDetectionProcesses （故障发现阶段的）钩子脚本
--> AttemptFailureDetectionRegistration //  尝试往数据库中插入故障发现记录 ，如果失败 意味着这个问题可能已经被发现了，
--> checkAndRecoverDeadMaster  // 根据故障情况 执行恢复，这里选择DeadMaster 故障类型举例 
--> AttemptRecoveryRegistration // 尝试往数据库中插入一条恢复记录；如果这一尝试失败，那么意味着恢复已经在进行中。
--> recoverDeadMaster //  用于恢复DeadMaster故障类型的函数，其中包含了完整的逻辑。会执行PreFailoverProcesses 钩子脚本

GetReplicationAnalysis

该函数将检查复制问题 (dead master; unreachable master; 等），根据实例的状态确定故障或者警告类型。

该函数会运行一个复杂SQL ,该SQL会每秒执行一次 ，执行间隔是由定时器 recoveryTick决定 ，SQL如下

SELECT
		master_instance.hostname,
		master_instance.port,
		master_instance.read_only AS read_only,
		MIN(master_instance.data_center) AS data_center,
		MIN(master_instance.region) AS region,
		MIN(master_instance.physical_environment) AS physical_environment,
		MIN(master_instance.master_host) AS master_host,
		MIN(master_instance.master_port) AS master_port,
		MIN(master_instance.cluster_name) AS cluster_name,
		MIN(master_instance.binary_log_file) AS binary_log_file,
		MIN(master_instance.binary_log_pos) AS binary_log_pos,
		MIN(
			IFNULL(
				master_instance.binary_log_file = database_instance_stale_binlog_coordinates.binary_log_file
				AND master_instance.binary_log_pos = database_instance_stale_binlog_coordinates.binary_log_pos
				AND database_instance_stale_binlog_coordinates.first_seen < NOW() - interval 10 second,
				0
			)
		) AS is_stale_binlog_coordinates,
		MIN(
			IFNULL(
				cluster_alias.alias,
				master_instance.cluster_name
			)
		) AS cluster_alias,
		MIN(
			IFNULL(
				cluster_domain_name.domain_name,
				master_instance.cluster_name
			)
		) AS cluster_domain,
		MIN(
			master_instance.last_checked <= master_instance.last_seen
			and master_instance.last_attempted_check <= master_instance.last_seen + interval 6 second
		) = 1 AS is_last_check_valid,
		/* To be considered a master, traditional async replication must not be present/valid AND the host should either */
		/* not be a replication group member OR be the primary of the replication group */
		MIN(master_instance.last_check_partial_success) as last_check_partial_success,
		MIN(
			(
				master_instance.master_host IN ('', '_')
				OR master_instance.master_port = 0
				OR substr(master_instance.master_host, 1, 2) = '//'
			)
			AND (
				master_instance.replication_group_name = ''
				OR master_instance.replication_group_member_role = 'PRIMARY'
			)
		) AS is_master,
		MIN(
			master_instance.replication_group_name != ''
			AND master_instance.replication_group_member_state != 'OFFLINE'
		) AS is_replication_group_member,
		MIN(master_instance.is_co_master) AS is_co_master,
		MIN(
			CONCAT(
				master_instance.hostname,
				':',
				master_instance.port
			) = master_instance.cluster_name
		) AS is_cluster_master,
		MIN(master_instance.gtid_mode) AS gtid_mode,
		COUNT(replica_instance.server_id) AS count_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
			),
			0
		) AS count_valid_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.slave_io_running != 0
				AND replica_instance.slave_sql_running != 0
			),
			0
		) AS count_valid_replicating_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.slave_io_running = 0
				AND replica_instance.last_io_error like '%error %connecting to master%'
				AND replica_instance.slave_sql_running = 1
			),
			0
		) AS count_replicas_failing_to_connect_to_master,
		MIN(master_instance.replication_depth) AS replication_depth,
		GROUP_CONCAT(
			concat(
				replica_instance.Hostname,
				':',
				replica_instance.Port
			)
		) as slave_hosts,
		MIN(
			master_instance.slave_sql_running = 1
			AND master_instance.slave_io_running = 0
			AND master_instance.last_io_error like '%error %connecting to master%'
		) AS is_failing_to_connect_to_master,
		MIN(
			master_downtime.downtime_active is not null
			and ifnull(master_downtime.end_timestamp, now()) > now()
		) AS is_downtimed,
		MIN(
			IFNULL(master_downtime.end_timestamp, '')
		) AS downtime_end_timestamp,
		MIN(
			IFNULL(
				unix_timestamp() - unix_timestamp(master_downtime.end_timestamp),
				0
			)
		) AS downtime_remaining_seconds,
		MIN(
			master_instance.binlog_server
		) AS is_binlog_server,
		MIN(master_instance.pseudo_gtid) AS is_pseudo_gtid,
		MIN(
			master_instance.supports_oracle_gtid
		) AS supports_oracle_gtid,
		MIN(
			master_instance.semi_sync_master_enabled
		) AS semi_sync_master_enabled,
		MIN(
			master_instance.semi_sync_master_wait_for_slave_count
		) AS semi_sync_master_wait_for_slave_count,
		MIN(
			master_instance.semi_sync_master_clients
		) AS semi_sync_master_clients,
		MIN(
			master_instance.semi_sync_master_status
		) AS semi_sync_master_status,
		SUM(replica_instance.is_co_master) AS count_co_master_replicas,
		SUM(replica_instance.oracle_gtid) AS count_oracle_gtid_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.oracle_gtid != 0
			),
			0
		) AS count_valid_oracle_gtid_replicas,
		SUM(
			replica_instance.binlog_server
		) AS count_binlog_server_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.binlog_server != 0
			),
			0
		) AS count_valid_binlog_server_replicas,
		SUM(
			replica_instance.semi_sync_replica_enabled
		) AS count_semi_sync_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.semi_sync_replica_enabled != 0
			),
			0
		) AS count_valid_semi_sync_replicas,
		MIN(
			master_instance.mariadb_gtid
		) AS is_mariadb_gtid,
		SUM(replica_instance.mariadb_gtid) AS count_mariadb_gtid_replicas,
		IFNULL(
			SUM(
				replica_instance.last_checked <= replica_instance.last_seen
				AND replica_instance.mariadb_gtid != 0
			),
			0
		) AS count_valid_mariadb_gtid_replicas,
		IFNULL(
			SUM(
				replica_instance.log_bin
				AND replica_instance.log_slave_updates
			),
			0
		) AS count_logging_replicas,
		IFNULL(
			SUM(
				replica_instance.log_bin
				AND replica_instance.log_slave_updates
				AND replica_instance.binlog_format = 'STATEMENT'
			),
			0
		) AS count_statement_based_logging_replicas,
		IFNULL(
			SUM(
				replica_instance.log_bin
				AND replica_instance.log_slave_updates
				AND replica_instance.binlog_format = 'MIXED'
			),
			0
		) AS count_mixed_based_logging_replicas,
		IFNULL(
			SUM(
				replica_instance.log_bin
				AND replica_instance.log_slave_updates
				AND replica_instance.binlog_format = 'ROW'
			),
			0
		) AS count_row_based_logging_replicas,
		IFNULL(
			SUM(replica_instance.sql_delay > 0),
			0
		) AS count_delayed_replicas,
		IFNULL(
			SUM(replica_instance.slave_lag_seconds > 10),
			0
		) AS count_lagging_replicas,
		IFNULL(MIN(replica_instance.gtid_mode), '') AS min_replica_gtid_mode,
		IFNULL(MAX(replica_instance.gtid_mode), '') AS max_replica_gtid_mode,
		IFNULL(
			MAX(
				case when replica_downtime.downtime_active is not null
				and ifnull(replica_downtime.end_timestamp, now()) > now() then '' else replica_instance.gtid_errant end
			),
			''
		) AS max_replica_gtid_errant,
		IFNULL(
			SUM(
				replica_downtime.downtime_active is not null
				and ifnull(replica_downtime.end_timestamp, now()) > now()
			),
			0
		) AS count_downtimed_replicas,
		COUNT(
			DISTINCT case when replica_instance.log_bin
			AND replica_instance.log_slave_updates then replica_instance.major_version else NULL end
		) AS count_distinct_logging_major_versions
	FROM
		database_instance master_instance
		LEFT JOIN hostname_resolve ON (
			master_instance.hostname = hostname_resolve.hostname
		)
		LEFT JOIN database_instance replica_instance ON (
			COALESCE(
				hostname_resolve.resolved_hostname,
				master_instance.hostname
			) = replica_instance.master_host
			AND master_instance.port = replica_instance.master_port
		)
		LEFT JOIN database_instance_maintenance ON (
			master_instance.hostname = database_instance_maintenance.hostname
			AND master_instance.port = database_instance_maintenance.port
			AND database_instance_maintenance.maintenance_active = 1
		)
		LEFT JOIN database_instance_stale_binlog_coordinates ON (
			master_instance.hostname = database_instance_stale_binlog_coordinates.hostname
			AND master_instance.port = database_instance_stale_binlog_coordinates.port
		)
		LEFT JOIN database_instance_downtime as master_downtime ON (
			master_instance.hostname = master_downtime.hostname
			AND master_instance.port = master_downtime.port
			AND master_downtime.downtime_active = 1
		)
		LEFT JOIN database_instance_downtime as replica_downtime ON (
			replica_instance.hostname = replica_downtime.hostname
			AND replica_instance.port = replica_downtime.port
			AND replica_downtime.downtime_active = 1
		)
		LEFT JOIN cluster_alias ON (
			cluster_alias.cluster_name = master_instance.cluster_name
		)
		LEFT JOIN cluster_domain_name ON (
			cluster_domain_name.cluster_name = master_instance.cluster_name
		)
	WHERE
		database_instance_maintenance.database_instance_maintenance_id IS NULL
		AND '' IN ('', master_instance.cluster_name)
	GROUP BY
		master_instance.hostname,
		master_instance.port

			HAVING
				(
					MIN(
						master_instance.last_checked <= master_instance.last_seen
						and master_instance.last_attempted_check <= master_instance.last_seen + interval 6 second
					) = 1
					/* AS is_last_check_valid */
				) = 0
				OR (
					IFNULL(
						SUM(
							replica_instance.last_checked <= replica_instance.last_seen
							AND replica_instance.slave_io_running = 0
							AND replica_instance.last_io_error like '%error %connecting to master%'
							AND replica_instance.slave_sql_running = 1
						),
						0
					)
					/* AS count_replicas_failing_to_connect_to_master */
					> 0
				)
				OR (
					IFNULL(
						SUM(
							replica_instance.last_checked <= replica_instance.last_seen
						),
						0
					)
					/* AS count_valid_replicas */
					< COUNT(replica_instance.server_id)
					/* AS count_replicas */
				)
				OR (
					IFNULL(
						SUM(
							replica_instance.last_checked <= replica_instance.last_seen
							AND replica_instance.slave_io_running != 0
							AND replica_instance.slave_sql_running != 0
						),
						0
					)
					/* AS count_valid_replicating_replicas */
					< COUNT(replica_instance.server_id)
					/* AS count_replicas */
				)
				OR (
					MIN(
						master_instance.slave_sql_running = 1
						AND master_instance.slave_io_running = 0
						AND master_instance.last_io_error like '%error %connecting to master%'
					)
					/* AS is_failing_to_connect_to_master */
				)
				OR (
					COUNT(replica_instance.server_id)
					/* AS count_replicas */
					> 0
				)

	ORDER BY
		is_master DESC,
		is_cluster_master DESC,
		count_replicas DESC\G

故障类型和对应的处理函数

与MHA相比