Description:
mysql ha environment have three node Group Membership
a member to go offline for a short time, then attempt to rejoin the group again. not success.
1）mysql_error.log detail:
2019-10-10T21:06:54.560209+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707128145198210.'
2019-10-10T21:08:04.462954+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707128844370170.'
2019-10-10T21:09:14.443355+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707129544133390.'
2019-10-10T21:10:24.333606+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707130243001550.'
2019-10-10T21:11:34.675202+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707130946302240.'
2019-10-10T21:12:44.577184+08:00 0 [Note] Plugin group_replication reported: 'Old incarnation found while trying to add node 21.106.97.239:33061 15707131645508930.'
2）pstack find XCom check：
Thread 37 (Thread 0x2b6a1733f700 (LWP 19245)):
#0 0x00002b6873be0995 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002b6a14784e43 in Gcs_xcom_engine::process (this=0x2b6a441084a0) at /export/home/pb2/build/sb_0-33648028-1555164244.06/mysql-5.7.26/rapid/plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_xcom_notification.cc:210
#2 0x00002b6a14784ec9 in process_notification_thread (ptr_object=<optimized out>) at /export/home/pb2/build/sb_0-33648028-1555164244.06/mysql-5.7.26/rapid/plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_xcom_notification.cc:159
#3 0x00002b6873bdce25 in start_thread () from /lib64/libpthread.so.0
4）MySQL 5.7 Reference Manual
from MySQL 5.7.22, servers are given a unique identifier when they join a group. This enables Group Replication to be aware of the situation where a new incarnation of the same server (with the same address but a new identifier) is trying to join the group while its old incarnation is still listed as a member. The new incarnation is blocked from joining the group until the old incarnation can be removed by a reconfiguration. If Group Replication is stopped and restarted on the server, the member becomes a new incarnation and cannot rejoin until the suspicion times out
5）find this variables "group_replication_member_expel_timeout" can fix this problem
【8.0 have】https://dev.mysql.com/doc/refman/8.0/en/group-replication-options.html#sysvar_group_replic...
【5.7 no have】https://dev.mysql.com/doc/refman/5.7/en/group-replication-options.html
How to repeat:
The environment：
centos7.4
mysql version 5.7.26
member:three
one master
scene ：
networt problem leave group
Suggested fix:
5.7 version add 8.0 mgr parameter "group_replication_member_expel_timeout"
or
automic fix this scene problem
