You can use the
system variable, which is available from MySQL 8.0.13, to allow
additional time between the creation of a suspicion and the
expulsion of the suspect member.
A group member is expelled when another member's suspicion of it
(or its own suspicion of itself) times out. By default,
is set to 0, meaning that there is no waiting period and a
suspected member is liable for expulsion immediately after the
5-second detection period ends. An additional short period of
time might elapse before the expelling mechanism detects and
implements the expulsion. If a group member is at an older MySQL
Server version that does not support this setting, this is its
behavior towards other members or itself.
To avoid unnecessary expulsions on slower networks, or in the
case of expected transient network failures or machine
slowdowns, you can specify a timeout value greater than zero, up
to a maximum of 3600 seconds (1 hour). Suspect members in this
state are listed as
UNREACHABLE, but are not
removed from the group's membership list. If a suspect member
becomes active again before the suspicion times out, it rejoins
the group, applies all the messages that were buffered by the
remaining group members, and enters
If the timeout is exceeded, the suspect member is liable for
expulsion immediately after the suspicion times out. If the
member is able to resume communications and receives a view
where it is expelled, it realises it was expelled. By default,
the expelled member then follows the exit action specified by
Alternatively you can use the
system variable, which is available from MySQL 8.0.16, to make
the member automatically try to rejoin the group.
The waiting period before expelling a member only applies to members that have previously been active in the group. Non-members that were never active in the group do not get this waiting period and are removed after the initial detection period because they took too long to join.
If any members in a group are currently under suspicion, the
group membership cannot be reconfigured (by adding or removing
members or electing a new leader). If group membership changes
need to be implemented while one or more members are under
suspicion, and you want the suspect members to remain in the
group, take any actions required to make the members active
again, if that is possible. If you cannot make the members
active again and you want them to be expelled from the group,
you can force the suspicions to time out immediately. Do this by
changing the value of
on any active members to a value lower than the time that has
already elapsed since the suspicions were created. The suspect
members then become liable for expulsion immediately.
For alternative mitigation strategies to avoid unnecessary
expulsions where the
system variable is not available, see
Section 18.9.2, “Group Replication Limitations”.