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社区首页 >专栏 >MySQL主从复制之增强半同步（无损复制）、延迟复制和并行复制

MySQL主从复制之增强半同步（无损复制）、延迟复制和并行复制

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AiDBA宝典
发布于 2023-04-26 11:17:30
发布于 2023-04-26 11:17:30
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文章被收录于专栏：小麦苗的DB宝专栏小麦苗的DB宝专栏
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简介

MySQL主从复制过程：

主从复制方式

MySQL有四种同步方式： 1、异步复制（Async Replication） 2、同步复制（sync Replication） 3、半同步复制（Async Replication） 4、增强半同步复制（lossless Semi-Sync Replication）、无损复制

1、异步复制（Async Replication） 主库将更新写入Binlog日志文件后，不需要等待数据更新是否已经复制到从库中，就可以继续处理更多的请求。Master将事件写入binlog，但并不知道Slave是否或何时已经接收且已处理。在异步复制的机制的情况下，如果Master宕机，事务在Master上已提交，但很可能这些事务没有传到任何的Slave上。假设有Master->Salve故障转移的机制，此时Slave也可能会丢失事务。MySQL复制默认是异步复制，异步复制提供了最佳性能。

2、同步复制（Sync Replication） 主库将更新写入Binlog日志文件后，需要等待数据更新已经复制到从库中，并且已经在从库执行成功，然后才能返回继续处理其它的请求。同步复制提供了最佳安全性，保证数据安全，数据不会丢失，但对性能有一定的影响。

3、半同步复制（Semi-Sync Replication） 主库提交更新写入二进制日志文件后，等待数据更新写入了从服务器中继日志中，然后才能再继续处理其它请求。该功能确保至少有1个从库接收完主库传递过来的binlog内容已经写入到自己的relay log里面了，才会通知主库上面的等待线程，该操作完毕。 半同步复制，是最佳安全性与最佳性能之间的一个折中。 MySQL 5.5版本之后引入了半同步复制功能，主从服务器必须安装半同步复制插件，才能开启该复制功能。如果等待超时，超过rpl_semi_sync_master_timeout参数设置时间（默认值为10000，表示10秒），则关闭半同步复制，并自动转换为异步复制模式。当master dump线程发送完一个事务的所有事件之后，如果在rpl_semi_sync_master_timeout内，收到了从库的响应，则主从又重新恢复为增强半同步复制。 ACK (Acknowledge character）即是确认字符。

4、增强半同步复制（lossless Semi-Sync Replication、无损复制） 增强半同步是在MySQL 5.7引入，其实半同步可以看成是一个过渡功能，因为默认的配置就是增强半同步，所以，大家一般说的半同步复制其实就是增强的半同步复制，也就是无损复制。 增强半同步和半同步不同的是，等待ACK时间不同 rpl_semi_sync_master_wait_point = AFTER_SYNC（默认） 半同步的问题是因为等待ACK的点是Commit之后，此时Master已经完成数据变更，用户已经可以看到最新数据，当Binlog还未同步到Slave时，发生主从切换，那么此时从库是没有这个最新数据的，用户看到的是老数据。 增强半同步将等待ACK的点放在提交Commit之前，此时数据还未被提交，外界看不到数据变更，此时如果发送主从切换，新库依然还是老数据，不存在数据不一致的问题。

图示如下：

异步复制示例

MySQL主从复制之1主2从异步复制搭建及同步测试参考：https://www.xmmup.com/dbbao64mysqlzhucongzhi1zhu2congyibufuzhidajianjitongbuceshi.html

如何配置半同步复制

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1.分别在主从安装插件
  主： INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
  从： INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
2.主服务器开启半同步
  set global  rpl_semi_sync_master_enabled=on;
3.从服务器开启半同步
  set global  rpl_semi_sync_slave_enabled=on;

4.配置主从同步（GTID模式示例）
server-id=1   （从为2，保证唯一性）
log-bin=master-bin  
log-bin-index=master-bin.index
binlog-format=ROW
gtid-mode=on
enforce-gtid-consistency=true

延迟从库

延迟从库:从库落后于主库一段时间。 SQL线程延时:数据已经写入relaylog中了,只是让SQL线程"慢点"运行

MySQL延迟复制的好处主要有几点： 1.误删除时，能更快恢复数据。有时候手抖了，把线上数据给误删除了，或者误删除库、表、其他对象，或不加WHERE条件的更新、删除，都可以让延迟从库在误操作前的时间点停下，然后进行恢复。 2.把延迟从库作为专用的备份节点。虽然有一定的延迟，但并不影响利用该节点作为备份角色，也不影响生产节点数据库。 3.还可以把延迟从库当做一些问题、案例研究的对象。个别时候，可能有些Binlog Event在普通从库上会有问题（例如：早期版本中无主键会导致从库更新非常慢的经典问题），这时就有时间在延迟从库上慢慢琢磨研究了。

一般企业建议3-6小时，具体看公司运维人员对于故障的反应时间。

启用延迟从库的方法也挺简单的：

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#直接用CHANGE MASTER TO设置，后面的N单位是秒数：
STOP SLAVE SQL_THREAD;
CHANGE MASTER TO MASTER_DELAY = N;
START SLAVE SQL_THREAD;
查询：
show slave status\G
SQL_Delay: 0

并行复制

MySQL 5.6提供了并行复制，但是这种并行只是基于database的（slave-parallel-type=DATABASE）。如果用户的MySQL数据库实例中存在多个database，对于从库复制的速度的确可以有比较大的帮助。如果是基于单个database的复制依然无法做到真正的并行回放，这个阶段很多DBA将数据库进行垂直拆分，将一个database拆分成几个database，通过设置slave_parallel_workers=n，可以进行database级别的并行复制，但对于热点业务复制延迟依然无法解决。参数slave_parallel_workers默认值为0，表示禁用并行。

到了MySQL 5.7，才实现了真正的并行复制（slave-parallel-type=LOGICAL_CLOCK），复制效率提升很多。MySQL 5.7的并行复制，multi-threaded slave即MTS，期望最大化还原主库的并行度，实现方式是在binlog event中增加必要的信息，以便slave节点根据这些信息实现并行复制。

要开启 MySQL 5.7 并行复制需要以下2步： 1、首先在主库设置 binlog_group_commit_sync_delay 的值大于0 。

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set global binlog_group_commit_sync_delay=10;
set global binlog_group_commit_sync_no_delay_count=10;

binlog_group_commit_sync_delay 全局动态变量，单位微妙，默认0，范围：0～1000000（1秒）。 表示 binlog 提交后等待延迟多少时间再同步到磁盘，默认0 ，不延迟。当设置为 0 以上的时候，就允许多个事务的日志同时一起提交，也就是我们说的组提交。组提交是并行复制的基础，我们设置这个值的大于 0 就代表打开了组提交的功能。 binlog_group_commit_sync_no_delay_count 全局动态变量，单位个数，默认0，范围：0～1000000。 表示等待延迟提交的最大事务数，如果上面参数的时间没到，但事务数到了，则直接同步到磁盘。若 binlog_group_commit_sync_delay 没有开启，则该参数也不会开启。

2、其次要在 Slave 主机上设置如下几个参数：

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set global slave-parallel-type=LOGICAL_CLOCK;
set global slave-parallel-workers=16;

一、1主2从之增强半同步复制（无损复制）示例

半同步复制比异步复制多了如下步骤：

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-- 1.分别在主从安装插件
   主： INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
   从： INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
-- 2.主服务器开启半同步
 set global  rpl_semi_sync_master_enabled=on;
-- 3.从服务器开启半同步
 set global  rpl_semi_sync_slave_enabled=on;

1、MySQL环境初始化

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-- 设置主从的网络环境
docker pull mysql:5.7.36
docker network create --subnet=172.72.0.0/24 mysqln0


-- 删除之前的容器
docker rm -f MSS57M33650 MSS57S33651 MSS57S33652

-- 创建参数文件路径
mkdir -p /lhrmysqltest3/master/conf.d
mkdir -p /lhrmysqltest3/slave1/conf.d
mkdir -p /lhrmysqltest3/slave2/conf.d


-- 申请主库环境
docker run -d --name MSS57M33650 \
   -h master -p 33650:3306 --net=mysqln0 --ip 172.72.0.50 \
   -v /lhrmysqltest3/master/conf.d:/etc/mysql/conf.d  \
   -e MYSQL_ROOT_PASSWORD=lhr \
   mysql:5.7.36

-- 申请从库1环境
docker run -d --name MSS57S33651 \
   -h slave1 -p 33651:3306 --net=mysqln0 --ip 172.72.0.51 \
   -v /lhrmysqltest3/slave1/conf.d:/etc/mysql/conf.d \
   -e MYSQL_ROOT_PASSWORD=lhr \
   mysql:5.7.36

-- 申请从库2环境
docker run -d --name MSS57S33652 \
   -h slave2 -p 33652:3306 --net=mysqln0 --ip 172.72.0.52 \
   -v /lhrmysqltest3/slave2/conf.d:/etc/mysql/conf.d \
   -e MYSQL_ROOT_PASSWORD=lhr \
   mysql:5.7.36


-- 配置主库参数
cat > /lhrmysqltest3/master/conf.d/my.cnf <<"EOF"
[mysqld]
port=3306
character_set_server=utf8mb4
secure_file_priv=
server-id = 5733650
log-bin = 
binlog_format=row
skip-name-resolve
gtid-mode=ON
enforce-gtid-consistency=on
report_host=172.72.0.50
default-time-zone = '+8:00'
log_timestamps = SYSTEM
log_slave_updates = 1
master_info_repository='table'
relay_log_info_repository='table'
relay_log_recovery=1

EOF

-- 配置从库1参数
cat > /lhrmysqltest3/slave1/conf.d/my.cnf <<"EOF"
[mysqld]
port=3306
character_set_server=utf8mb4
secure_file_priv=
server-id = 5733651
log-bin = 
binlog_format=row
gtid-mode=ON
enforce-gtid-consistency=ON
skip_name_resolve
report_host=172.72.0.51
default-time-zone = '+8:00'
log_timestamps = SYSTEM
log_slave_updates = 1
master_info_repository='table'
relay_log_info_repository='table'
relay_log_recovery=1

EOF


-- 配置从库2参数
cat > /lhrmysqltest3/slave2/conf.d/my.cnf <<"EOF"
[mysqld]
user=mysql
port=3306
character_set_server=utf8mb4
secure_file_priv=
server-id = 5733652
log-bin = 
binlog_format=row
gtid-mode=ON
enforce-gtid-consistency=ON
skip_name_resolve
report_host=172.72.0.52
default-time-zone = '+8:00'
log_timestamps = SYSTEM
log_slave_updates = 1
master_info_repository='table'
relay_log_info_repository='table'
relay_log_recovery=1

EOF

-- 重启3台环境
docker restart MSS57M33650 MSS57S33651 MSS57S33652
docker ps

[root@docker35 ~]# docker ps
CONTAINER ID   IMAGE          COMMAND                  CREATED          STATUS          PORTS                                                    NAMES
b6311aac4c08   mysql:5.7.36   "docker-entrypoint.s…"   6 seconds ago    Up 3 seconds    33060/tcp, 0.0.0.0:33652->3306/tcp, :::33652->3306/tcp   MSS57S33652
b1f5f35c4fea   mysql:5.7.36   "docker-entrypoint.s…"   11 seconds ago   Up 8 seconds    33060/tcp, 0.0.0.0:33651->3306/tcp, :::33651->3306/tcp   MSS57S33651
9a9826423f2d   mysql:5.7.36   "docker-entrypoint.s…"   17 seconds ago   Up 15 seconds   33060/tcp, 0.0.0.0:33650->3306/tcp, :::33650->3306/tcp   MSS57M33650

-- 登陆
docker exec -it MSS57M33650 bash
docker exec -it MSS57M33650 mysql -uroot -plhr

-- 查询
mysql -uroot -plhr -h192.168.88.35 -P33650 -e "select @@hostname,@@server_id,@@server_uuid"
mysql -uroot -plhr -h192.168.88.35 -P33651 -e "select @@hostname,@@server_id,@@server_uuid"
mysql -uroot -plhr -h192.168.88.35 -P33652 -e "select @@hostname,@@server_id,@@server_uuid"

C:\Users\lhrxxt>mysql -uroot -plhr -h192.168.88.35 -P33650 -e "select @@hostname,@@server_id,@@server_uuid"
mysql: [Warning] Using a password on the command line interface can be insecure.
+------------+-------------+--------------------------------------+
| @@hostname | @@server_id | @@server_uuid                        |
+------------+-------------+--------------------------------------+
| master     |     5733650 | a5c6a094-dbf1-11ec-8f03-0242ac480032 |
+------------+-------------+--------------------------------------+

C:\Users\lhrxxt>mysql -uroot -plhr -h192.168.88.35 -P33651 -e "select @@hostname,@@server_id,@@server_uuid"
mysql: [Warning] Using a password on the command line interface can be insecure.
+------------+-------------+--------------------------------------+
| @@hostname | @@server_id | @@server_uuid                        |
+------------+-------------+--------------------------------------+
| slave1     |     5733651 | a99e5d38-dbf1-11ec-bfe9-0242ac480033 |
+------------+-------------+--------------------------------------+

C:\Users\lhrxxt>mysql -uroot -plhr -h192.168.88.35 -P33652 -e "select @@hostname,@@server_id,@@server_uuid"
mysql: [Warning] Using a password on the command line interface can be insecure.
+------------+-------------+--------------------------------------+
| @@hostname | @@server_id | @@server_uuid                        |
+------------+-------------+--------------------------------------+
| slave2     |     5733652 | ac918575-dbf1-11ec-b236-0242ac480034 |
+------------+-------------+--------------------------------------+

2、主库配置

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-- 主库创建复制用户repl
mysql -uroot -plhr -h192.168.88.35 -P33650
grant replication slave on *.* to repl@'%' identified by 'lhr';
select user,host,grant_priv,password_last_changed,authentication_string from mysql.user; 

create database lhrdb;
use lhrdb;
create table mytb1(id int,name varchar(30));
insert into mytb1 values(1,'a'),(2,'b');


-- 安装插件
INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
SELECT PLUGIN_NAME, PLUGIN_STATUS FROM INFORMATION_SCHEMA.PLUGINS  WHERE PLUGIN_NAME LIKE '%semi%';

-- 配置参数，后期需要配置到参数文件中去
set global  rpl_semi_sync_master_enabled=on;

-- 查询
show master status ;
show slave hosts;
select @@hostname,@@server_id,@@server_uuid;

执行过程：

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MySQL [lhrdb]> show master status ;
+-------------------+----------+--------------+------------------+------------------------------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                        |
+-------------------+----------+--------------+------------------+------------------------------------------+
| master-bin.000004 |     1085 |              |                  | 1bc15639-bc5b-11eb-b1eb-0242ac480032:1-9 |
+-------------------+----------+--------------+------------------+------------------------------------------+
1 row in set (0.06 sec)

MySQL [lhrdb]> show slave hosts;
Empty set (0.06 sec)

MySQL [lhrdb]> select @@hostname,@@server_id,@@server_uuid;
+------------+-------------+--------------------------------------+
| @@hostname | @@server_id | @@server_uuid                        |
+------------+-------------+--------------------------------------+
| master     |   5733650 | 1bc15639-bc5b-11eb-b1eb-0242ac480032 |
+------------+-------------+--------------------------------------+
1 row in set (0.05 sec)


MySQL [lhrdb]> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
Query OK, 0 rows affected (0.08 sec)

MySQL [(none)]> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
Query OK, 0 rows affected (0.08 sec)

MySQL [lhrdb]> SELECT PLUGIN_NAME, PLUGIN_STATUS FROM INFORMATION_SCHEMA.PLUGINS  WHERE PLUGIN_NAME LIKE '%semi%';
+----------------------+---------------+
| PLUGIN_NAME          | PLUGIN_STATUS |
+----------------------+---------------+
| rpl_semi_sync_master | ACTIVE        |
| rpl_semi_sync_slave  | ACTIVE        |
+----------------------+---------------+
2 rows in set (0.00 sec)

MySQL [lhrdb]> set global  rpl_semi_sync_master_enabled=on;
Query OK, 0 rows affected (0.05 sec)

MySQL [lhrdb]> show variables like '%semi%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 10000      |
| rpl_semi_sync_master_trace_level          | 32         |
| rpl_semi_sync_master_wait_for_slave_count | 1          |
| rpl_semi_sync_master_wait_no_slave        | ON         |
| rpl_semi_sync_master_wait_point           | AFTER_SYNC |
| rpl_semi_sync_slave_enabled               | OFF        |
| rpl_semi_sync_slave_trace_level           | 32         |
+-------------------------------------------+------------+
8 rows in set (0.01 sec)

3、从库1配置

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-- 从库1
mysql -uroot -plhr -h192.168.88.35 -P33651

-- 安装插件
INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
SELECT PLUGIN_NAME, PLUGIN_STATUS FROM INFORMATION_SCHEMA.PLUGINS  WHERE PLUGIN_NAME LIKE '%semi%';


-- 配置参数，后期需要配置到参数文件中去
set global  rpl_semi_sync_slave_enabled=on;


-- 修改参数
change master to
master_host='172.72.0.50',
master_port=3306,
master_user='repl',
master_password='lhr',
master_auto_position=1;

-- 启动复制进程
start slave; 
show slave status \G;

SELECT * FROM lhrdb.mytb1;

-- 主库：
insert into mytb1 values(3,'c'),(4,'d');

4、从库2配置

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-- S2
mysql -uroot -plhr -h192.168.88.35 -P33652



-- 安装插件
INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
SELECT PLUGIN_NAME, PLUGIN_STATUS FROM INFORMATION_SCHEMA.PLUGINS  WHERE PLUGIN_NAME LIKE '%semi%';

-- 配置参数，后期需要配置到参数文件中去
set global  rpl_semi_sync_slave_enabled=on;


-- 修改参数
change master to master_host='172.72.0.50',
master_port=3306,
master_user='repl',
master_password='lhr',
master_auto_position=1;

start slave; 
show slave status \G;

SELECT * FROM lhrdb.mytb1;

5、主从查询

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-- 主库
show slave hosts;
show master status;
show global status like 'rpl_semi%';
show variables like '%Rpl%';

-- 从库
show slave status;
show variables like '%Rpl%';



-- 线程查询
SELECT *
FROM performance_schema.threads a
WHERE a.`NAME` IN ( 'thread/sql/slave_IO', 'thread/sql/slave_sql' ) or a.PROCESSLIST_COMMAND in ('Binlog Dump','Binlog Dump GTID') ;

SELECT * FROM  information_schema.`PROCESSLIST` a where a.USER='system user' or a.command  in ('Binlog Dump','Binlog Dump GTID') ;

半同步复制查询：

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-- 主库
MySQL [lhrdb]> show global status like 'rpl_semi%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 2     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 1     |
| Rpl_semi_sync_master_no_times              | 0     |
| Rpl_semi_sync_master_no_tx                 | 0     |
| Rpl_semi_sync_master_status                | ON    |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 747   |
| Rpl_semi_sync_master_tx_wait_time          | 747   |
| Rpl_semi_sync_master_tx_waits              | 1     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 1     |
| Rpl_semi_sync_slave_status                 | OFF   |
+--------------------------------------------+-------+
15 rows in set (0.01 sec)

MySQL [lhrdb]> show variables like '%Rpl%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 10000      |
| rpl_semi_sync_master_trace_level          | 32         |
| rpl_semi_sync_master_wait_for_slave_count | 1          |
| rpl_semi_sync_master_wait_no_slave        | ON         |
| rpl_semi_sync_master_wait_point           | AFTER_SYNC |
| rpl_semi_sync_slave_enabled               | OFF        |
| rpl_semi_sync_slave_trace_level           | 32         |
| rpl_stop_slave_timeout                    | 31536000   |
+-------------------------------------------+------------+
9 rows in set (0.09 sec)

-- 从库
MySQL [(none)]> show global status like 'Rpl_semi_sync_slave_status%';
+----------------------------+-------+
| Variable_name              | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON    |
+----------------------------+-------+
1 row in set (0.05 sec)

Rpl_semi_sync_master_clients表示记录支持半同步的slave的个数

Rpl_semi_sync_master_status标记master现在是否是半同步复制状态

6、测试半同步复制

测试过程：

1、关闭从库io线程，模拟网络卡顿 2、主库插入数据，等待10秒，同步方式自动转换为异步模式 3、从库启动io线程 4、同步方式变为半同步模式

先关闭一个从库，我们测试1主1从的情况。

二、配置延迟复制示例

我们把从库2配置为延迟从库，如下所示：

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STOP SLAVE SQL_THREAD;
CHANGE MASTER TO MASTER_DELAY = 120;
START SLAVE SQL_THREAD;

show slave status \G
返回：SQL_Delay: 120


-- 主库插入数据
insert into mytb1 values(5,'e'),(6,'f');
select * from mytb1;

-- 从库2查询
show slave status \G

Seconds_Behind_Master: 110
SQL_Remaining_Delay: 46
Slave_SQL_Running_State: Waiting until MASTER_DELAY seconds after master executed event

三、配置并行复制示例

3.1、主库配置

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set global binlog_group_commit_sync_delay=10;
set global binlog_group_commit_sync_no_delay_count=10;
show variables like 'binlog_group_commit_sync_%';

3.2、从库2配置并行复制

只在从库2做配置，从库1不做配置。

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STOP SLAVE SQL_THREAD;
set global slave_parallel_type=LOGICAL_CLOCK;
set global slave_parallel_workers=4;

show variables like 'slave_parallel%';

start SLAVE SQL_THREAD;

-- 线程查询
SELECT *
FROM performance_schema.threads a
WHERE a.`NAME` IN ( 'thread/sql/slave_IO', 'thread/sql/slave_sql','thread/sql/slave_worker' ) or a.PROCESSLIST_COMMAND in ('Binlog Dump','Binlog Dump GTID') ;

SELECT * FROM  information_schema.`PROCESSLIST` a where a.USER='system user' or a.command  in ('Binlog Dump','Binlog Dump GTID') ;


MySQL [(none)]> SELECT *
    -> FROM performance_schema.threads a
    -> WHERE a.`NAME` IN ( 'thread/sql/slave_IO', 'thread/sql/slave_sql','thread/sql/slave_worker' ) or a.PROCESSLIST_COMMAND in ('Binlog Dump','Binlog Dump GTID') ;
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
| THREAD_ID | NAME                    | TYPE       | PROCESSLIST_ID | PROCESSLIST_USER | PROCESSLIST_HOST | PROCESSLIST_DB | PROCESSLIST_COMMAND | PROCESSLIST_TIME | PROCESSLIST_STATE                                      | PROCESSLIST_INFO | PARENT_THREAD_ID | ROLE | INSTRUMENTED | HISTORY | CONNECTION_TYPE | THREAD_OS_ID |
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
|        33 | thread/sql/slave_io     | FOREGROUND |              8 | root             | 172.72.0.1       | NULL           | Connect             |             1203 | Waiting for master to send event                       | NULL             |               30 | NULL | YES          | YES     | NULL            |           79 |
|        36 | thread/sql/slave_sql    | FOREGROUND |             11 | root             | 172.72.0.1       | NULL           | Connect             |              312 | Slave has read all relay log; waiting for more updates | NULL             |               30 | NULL | YES          | YES     | NULL            |           82 |
|        37 | thread/sql/slave_worker | FOREGROUND |             12 | root             | 172.72.0.1       | NULL           | Connect             |              312 | Waiting for an event from Coordinator                  | NULL             |               36 | NULL | YES          | YES     | NULL            |           83 |
|        38 | thread/sql/slave_worker | FOREGROUND |             13 | root             | 172.72.0.1       | NULL           | Connect             |              312 | Waiting for an event from Coordinator                  | NULL             |               36 | NULL | YES          | YES     | NULL            |           84 |
|        39 | thread/sql/slave_worker | FOREGROUND |             14 | root             | 172.72.0.1       | NULL           | Connect             |              312 | Waiting for an event from Coordinator                  | NULL             |               36 | NULL | YES          | YES     | NULL            |           85 |
|        40 | thread/sql/slave_worker | FOREGROUND |             15 | root             | 172.72.0.1       | NULL           | Connect             |              312 | Waiting for an event from Coordinator                  | NULL             |               36 | NULL | YES          | YES     | NULL            |           86 |
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
6 rows in set (0.05 sec)

MySQL [(none)]> SELECT * FROM  information_schema.`PROCESSLIST` a where a.USER='system user' or a.command  in ('Binlog Dump','Binlog Dump GTID') ;
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
| ID | USER        | HOST | DB   | COMMAND | TIME | STATE                                                  | INFO |
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
| 14 | system user |      | NULL | Connect |   37 | Waiting for an event from Coordinator                  | NULL |
| 15 | system user |      | NULL | Connect |   37 | Waiting for an event from Coordinator                  | NULL |
| 12 | system user |      | NULL | Connect |   37 | Waiting for an event from Coordinator                  | NULL |
| 13 | system user |      | NULL | Connect |   37 | Waiting for an event from Coordinator                  | NULL |
| 11 | system user |      | NULL | Connect |   37 | Slave has read all relay log; waiting for more updates | NULL |
|  8 | system user |      | NULL | Connect |  928 | Waiting for master to send event                       | NULL |
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
6 rows in set (0.05 sec)

3.3、主库压测测试并行复制

因为这里的架构为1主2从，我只配置了从库2为并行复制，从库1不是并行复制，那么接下来测试并行复制的效果。

首先，取消从库2的延迟复制功能：

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STOP SLAVE SQL_THREAD;
CHANGE MASTER TO MASTER_DELAY = 0;
START SLAVE SQL_THREAD;

show slave status \G
返回：SQL_Delay: 0

首先，主库进行压测生成数据：

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-- 主库修改
set GLOBAL max_connections=10000; 
set global max_prepared_stmt_count=65536;

-- 做压测
sysbench /usr/share/sysbench/oltp_common.lua --time=300 --mysql-host=172.72.0.50 --mysql-port=3306 \
--mysql-user=root --mysql-password=lhr --mysql-db=lhrdb --table-size=100000 --tables=10 \
--threads=16 --events=999999999   prepare


sysbench /usr/share/sysbench/oltp_read_write.lua --time=300 --mysql-host=172.72.0.50 --mysql-port=3306 \
--mysql-user=root --mysql-password=lhr --mysql-db=lhrdb --table-size=1000000 --tables=10 --threads=16 \
--events=999999999  --report-interval=10 --db-ps-mode=disable --forced-shutdown=1 run



-- 查询从库
mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master

结果：

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[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 126
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 62
[root@docker35 ~]# 
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 139
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 65
[root@docker35 ~]# 
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 214
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 78

可以看到，从库2比从库1能至少快一倍。

若是将从库的slave_parallel_workers配置为16，则配置了并行复制的库基本无延迟，而没有配置并行复制的库，延迟会越来越严重：

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STOP SLAVE SQL_THREAD;
set global slave_parallel_workers=16;

show variables like 'slave_parallel%';

start SLAVE SQL_THREAD;

-- 线程查询
SELECT *
FROM performance_schema.threads a
WHERE a.`NAME` IN ( 'thread/sql/slave_IO', 'thread/sql/slave_sql','thread/sql/slave_worker' ) or a.PROCESSLIST_COMMAND in ('Binlog Dump','Binlog Dump GTID') ;

SELECT * FROM  information_schema.`PROCESSLIST` a where a.USER='system user' or a.command  in ('Binlog Dump','Binlog Dump GTID') ;


MySQL [lhrdb]> -- 线程查询
MySQL [lhrdb]> SELECT *
    -> FROM performance_schema.threads a
    -> WHERE a.`NAME` IN ( 'thread/sql/slave_IO', 'thread/sql/slave_sql','thread/sql/slave_worker' ) or a.PROCESSLIST_COMMAND in ('Binlog Dump','Binlog Dump GTID') ;
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
| THREAD_ID | NAME                    | TYPE       | PROCESSLIST_ID | PROCESSLIST_USER | PROCESSLIST_HOST | PROCESSLIST_DB | PROCESSLIST_COMMAND | PROCESSLIST_TIME | PROCESSLIST_STATE                                      | PROCESSLIST_INFO | PARENT_THREAD_ID | ROLE | INSTRUMENTED | HISTORY | CONNECTION_TYPE | THREAD_OS_ID |
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
|        29 | thread/sql/slave_io     | FOREGROUND |              4 | root             | 192.168.88.64    | NULL           | Connect             |             1780 | Waiting for master to send event                       | NULL             |               28 | NULL | YES          | YES     | NULL            |          154 |
|       106 | thread/sql/slave_sql    | FOREGROUND |             81 | root             | 192.168.88.64    | NULL           | Connect             |               24 | Slave has read all relay log; waiting for more updates | NULL             |               28 | NULL | YES          | YES     | NULL            |          168 |
|       107 | thread/sql/slave_worker | FOREGROUND |             82 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          169 |
|       108 | thread/sql/slave_worker | FOREGROUND |             83 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          170 |
|       109 | thread/sql/slave_worker | FOREGROUND |             84 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          171 |
|       110 | thread/sql/slave_worker | FOREGROUND |             85 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          172 |
|       111 | thread/sql/slave_worker | FOREGROUND |             86 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          173 |
|       112 | thread/sql/slave_worker | FOREGROUND |             87 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          174 |
|       113 | thread/sql/slave_worker | FOREGROUND |             88 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          175 |
|       114 | thread/sql/slave_worker | FOREGROUND |             89 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          176 |
|       115 | thread/sql/slave_worker | FOREGROUND |             90 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          177 |
|       116 | thread/sql/slave_worker | FOREGROUND |             91 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          178 |
|       117 | thread/sql/slave_worker | FOREGROUND |             92 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          179 |
|       118 | thread/sql/slave_worker | FOREGROUND |             93 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          180 |
|       119 | thread/sql/slave_worker | FOREGROUND |             94 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          181 |
|       120 | thread/sql/slave_worker | FOREGROUND |             95 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          182 |
|       121 | thread/sql/slave_worker | FOREGROUND |             96 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          183 |
|       122 | thread/sql/slave_worker | FOREGROUND |             97 | root             | 192.168.88.64    | NULL           | Connect             |              322 | Waiting for an event from Coordinator                  | BEGIN            |              106 | NULL | YES          | YES     | NULL            |          184 |
+-----------+-------------------------+------------+----------------+------------------+------------------+----------------+---------------------+------------------+--------------------------------------------------------+------------------+------------------+------+--------------+---------+-----------------+--------------+
18 rows in set (0.01 sec)

MySQL [lhrdb]>
MySQL [lhrdb]> SELECT * FROM  information_schema.`PROCESSLIST` a where a.USER='system user' or a.command  in ('Binlog Dump','Binlog Dump GTID') ;
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
| ID | USER        | HOST | DB   | COMMAND | TIME | STATE                                                  | INFO |
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
| 96 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 97 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 94 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 95 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 92 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 93 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 90 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 91 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 88 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 89 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 86 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 87 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 84 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 82 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 85 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 83 | system user |      | NULL | Connect |  322 | Waiting for an event from Coordinator                  | NULL |
| 81 | system user |      | NULL | Connect |   24 | Slave has read all relay log; waiting for more updates | NULL |
|  4 | system user |      | NULL | Connect | 1780 | Waiting for master to send event                       | NULL |
+----+-------------+------+------+---------+------+--------------------------------------------------------+------+
18 rows in set (0.01 sec)

重新测试，可以看到从库2基本无延迟了：

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[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 50
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 0
[root@docker35 ~]# 
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
        Seconds_Behind_Master: 131
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 1

[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 210
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 1
[root@docker35 ~]# 
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33651 -e "show slave status \G" | grep Seconds_Behind_Master
mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Mastermysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 381
[root@docker35 ~]# mysql -uroot -plhr -h192.168.88.35 -P33652 -e "show slave status \G" | grep Seconds_Behind_Master
mysql: [Warning] Using a password on the command line interface can be insecure.
        Seconds_Behind_Master: 1
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原始发表：2022-06-20，如有侵权请联系 cloudcommunity@tencent.com 删除
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目录
  • 简介
    • 主从复制方式
    • 异步复制示例
    • 如何配置半同步复制
    • 延迟从库
    • 并行复制
  • 一、1主2从之增强半同步复制（无损复制）示例
    • 1、MySQL环境初始化
    • 2、主库配置
    • 3、从库1配置
    • 4、从库2配置
    • 5、主从查询
    • 6、测试半同步复制
  • 二、配置延迟复制示例
  • 三、配置并行复制示例
    • 3.1、主库配置
    • 3.2、从库2配置并行复制
    • 3.3、主库压测测试并行复制
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