一.基本环境
主库1: 10.24.65.30 3306 MySQL 5.7.14
主库2: 10.24.65.30 3307 mysql 5.7.14
从库：10.24.65.33 3306 mysql 5.7.14
基于gtid的多源复制。

二.gtid-mode的几种状态说明：
off :不产生gtid，基于binlog+position，slave也不能接受gtid的日志;
off_permissive:不产生gtid，但做为slave可以识别gtid事务也可以识别非gtid事务;
on_permissive:产生gtid事务，slave可以处理gtid事务和非gtid事务;
on:产生gtid事务，slave只接受gtid事务。

三.在线切换
1.停掉channel 'master-65303306'的复制,禁止:master_auto_position
先停掉master-65303306的slave，并记录下master_log_file和position信息。
stop slave for channel 'master-65303306';
(product)root@localhost [test]> show slave status for channel 'master-65303306'\G
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 10.24.65.30
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000435
Read_Master_Log_Pos: 234
Relay_Log_File: relay-bin-master@002d65303306.000507
Relay_Log_Pos: 447
Relay_Master_Log_File: mysql-bin.000435
Slave_IO_Running: No
Slave_SQL_Running: No
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 234
Relay_Log_Space: 1835
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 65303306
Master_UUID: 58abaa9b-73dd-11e6-9690-0050568a704b
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: 58abaa9b-73dd-11e6-9690-0050568a704b:1-16,
ebdca3fd-6eb7-11e6-b20c-0050568a704b:1-32459
Executed_Gtid_Set: 58abaa9b-73dd-11e6-9690-0050568a704b:1-16,
ebdca3fd-6eb7-11e6-b20c-0050568a704b:1-32459,
ebdca3fd-6eb7-11e6-b20c-0050568a704c:1-2
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name: master-65303306
Master_TLS_Version:
1 row in set (0.00 sec)
根据以上信息编写change master:
change master to master_auto_position=0,master_log_file='mysql-bin.000435',\
master_log_pos='234' for channel 'master-65303306';
start slave for channel 'master-65303306';