Motivation

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When coordinator on phase 1 detects that particular nodes don't reply in time with their local partition maps, it may decide to forcibly stop these nodes to unblock exchange.

It should be possible for user to configure a minimal number of copies. If stopping these nodes leads to partition loss coordinator checks user-provided policy to make this decision. If user allowed such actions coordinator proceeds with stopping otherwise warning is printed to logs.

If there is no risk of partition loss then coordinator stops nodes without any additional checks.

would cause some partitions to have less copies, coordinator should print warning to logs and keep waiting.

2 Non-coordinator node not applying full partition map

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If coordinator informs that exchange has already been finished nodeA should stop itself as its partition map is out-of-date with the rest of the cluster.

3 Coordinator node not sending full partition map to other nodes

When coordinator node detects that it received all local partition maps but didn't send back full partition map it should stop itselfIf coordinator hasn't initiated exchange for a given topology version, non-coordinator nodes should kick it from cluster.

Risks and Assumptions

Proposal requires defining new policy in public API for scenario#1, new protocol should be developed for scenario#2 (non-coordinator node requests status of specific exchange from coordinator).

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