Thanks Luke, I meant in pre 3.9.x, like 3.6.x or 3.7.x branch for example.
ttyl Dima On Wed, Aug 28, 2024 at 7:36 PM Luke Chen <show...@gmail.com> wrote: > Hi Dima, > > > I assume that unclean leader election exists as a static config in kafka > kraft, but is still unavailable dynamically? Or is it unavailable in > general? > > Let me make it clear. In v3.9.0, the `unclean.leader.election.enable` in > KRaft will work, either static config or dynamic config. > It's just the behavior changes when dynamically enabling the > `unclean.leader.election.enable`, which will not trigger unclean leader > election immediately after config change. The detailed behavior change is > as described above. > > Let me know if it's still not clear. > > Thanks. > Luke > > > On Thu, Aug 29, 2024 at 1:58 AM Dima Brodsky <ddbrod...@gmail.com> wrote: > > > Hi Luke, > > > > I assume that unclean leader election exists as a static config in kafka > > kraft, but is still unavailable dynamically? Or is it unavailable in > > general? > > > > Thanks! > > ttyl > > Dima > > > > > > On Wed, Aug 28, 2024 at 3:45 AM Luke Chen <show...@gmail.com> wrote: > > > > > Hi all, > > > > > > In v3.9.0, we're planning to support the > `unclean.leader.election.enable` > > > config in KRaft. Currently, the implementation PR > > > <https://github.com/apache/kafka/pull/16866> is under review now. But > > I'd > > > like to raise the discussion to let you know there will be one behavior > > > change when enabling `unclean.leader.election.enable` config > dynamically > > in > > > KRaft. > > > > > > scenario: > > > 1. broker [0, 1] config are all set > > `unclean.leader.election.enable=false`. > > > 2. topic A is created with 1 partition, 2 replication factors and > > > `unclean.leader.election.enable=false`. Leader of the partition 0 is 0. > > ISR > > > is [0]. > > > 3. broker 0 is down, which leaves ISR to empty [ ], and leader none. > > > 4. dynamically alter config using admin API to set > > > `unclean.leader.election.enable=true`, no matter it changes to the > topic > > A, > > > or to broker 1, or default broker. > > > > > > In ZK mode, with this scenario, it'll trigger unclean leader election > > > immediately, and broker 1 will be elected as the leader, which brings > the > > > availability of the partition back. > > > In KRaft mode, with this scenario, the unclean leader election will be > > > triggered in an unclean election thread, which is scheduled every 5 > mins > > by > > > default. That is, this partition might still be unavailable even if it > > > enables `unclean.leader.election.enable`. If users want to elect a > leader > > > for this partition, run `kafka-leader-election.sh` with `unclean` > option > > to > > > trigger the unclean leader election immediately. > > > > > > The main reason we didn't implement what ZK did is because of this > > > complication > > > <https://github.com/apache/kafka/pull/16284#discussion_r1635410206> we > > > faced. > > > > > > Other behaviors keep the same. Ex: When the topic config, or broker > > config, > > > or default broker config set `unclean.leader.election.enable=true`, and > > > later, a partition has leader down with empty ISR [ ], and having some > > > alive non-ISR replicas, in this case, the unclean leader election will > be > > > triggered, as long as the config was set earlier. > > > > > > But since the PR is still under review, any comments or thoughts are > > > welcomed. > > > > > > Thank you. > > > Luke > > > > > > > > > -- > > ddbrod...@gmail.com > > > > "The price of reliability is the pursuit of the utmost simplicity. > > It is a price which the very rich find the most hard to pay." > > (Sir > > Antony Hoare, 1980) > > > -- ddbrod...@gmail.com "The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich find the most hard to pay." (Sir Antony Hoare, 1980)
