simultaneous graceful leaving of two nodes leaves one remaining in non-PC

Bug #1217225 reported by Teemu Ollakka on 2013-08-27
This bug affects 5 people
Affects Status Importance Assigned to Milestone
Status tracked in 3.x
Teemu Ollakka
Teemu Ollakka

Bug Description

Sometimes when two out of three nodes leave the cluster almost simultaneously, the remaining node may end up in non-PC even if the nodes left gracefully.

Here is what happens:

1) Node 1 leaves the cluster, nodes 2 and 3 get the notification from EVS layer that node 1 left
2) Nodes 2 and 3 exchange states to form new PC view, but node 2 decides to leave just before message exchange is complete
3) Because forming new PC view was interrupted, node 3 loses the information that node 1 left gracefully, so final quorum computation for singleton view results non-PC

Expected behavior would be that the status of node 1 leaving gracefully would be preserved over intermediate view changes.

Note that if nodes 1 and 2 leave cluster so simultaneously that node 3 gets the notification of it in single view change or if nodes 2 and 3 finish the message exchange for new PC view before node 2 leaves, the outcome is that node 3 ends up in PC as expected.

Changed in galera:
assignee: nobody → Teemu Ollakka (teemu-ollakka)
description: updated
Changed in galera:
importance: Undecided → Medium
milestone: none → 24.2.8
status: New → Confirmed
Changed in galera:
milestone: 25.2.8 → 25.2.9
Revision history for this message
Darren Birkett (darren-birkett) wrote :

Presumably this never got fixed, or at least not fixed in a current release?

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