Hi PengHui, Thank you for your questions. Please find my answers inline. On Wed, Aug 2, 2023 at 3:47 AM PengHui Li <peng...@apache.org> wrote:
> Hi Heesung, > > I'm sorry for not getting back to you sooner. > The motivation and the solution look good to me. > > I just want to leave some comments to make the proposal clear > for users and developers. > > > ---------------------------------------------------------------------------------------------------- > > We should have a section to describe the values that will be added > by this proposal. > > - Reduced the publish latency spike and e2e latency spike during the > reconnecting > - Mitigated bottleneck(lookup) of a large number of topics in a cluster > > Maybe more, I can only think about the above two values. > > Good point. I will clarify this part in the PIP. ---------------------------------------------------------------------------------------------------- > > For the proto changes, the client side can also use the HTTP lookup > service. > We should also mention it in this proposal. Instead of adding four new > fields to > the CommandCloseProducer and CommandCloseConsumer, maybe adding a new > message BrokerIdentifier, or others is better. > I am worried about the backward compatibility if we add a new proto message -- how can the old versions of clients handle this new proto message? One of the advantages of this proposal (add these optional dstBrokerUrl fields in the existing CommandCloseProducer and CommandCloseConsumer) is the backward compatibility -- older clients can still work in the older way by going through the lookup requests. Ref: https://protobuf.dev/overview/#updating-defs Updating Proto Definitions Without Updating Code <https://protobuf.dev/overview/#updating-defs> It’s standard for software products to be backward compatible, but it is less common for them to be forward compatible. As long as you follow some simple practices <https://protobuf.dev/programming-guides/proto3/#updating> when updating .proto definitions, old code will read new messages without issues, ignoring any newly added fields. ... > > ---------------------------------------------------------------------------------------------------- > > There are two points we need to clarify in the proposal. > > - If the client reconnects before the new owner takes ownership. If the > producer closed > after the new broker took ownership, would it be a potential consistency > issue? - If the owner changed again before the client reconnection. How did Pulsar > handle this case? > As I understand, it's fine because the broker will check the ownership > again when handling > producer and consumer creation. If it can be explained in the proposal, > it should be great > for developers to understand it deeply. > After the client connects to the destination broker, the next command(e.g. ProducerCommand) requires the destination broker to check the ownership again against its local table view of the bundle state channel. Upon this local ownership check, there could be the following scenarios: Happy case: - If the ownership state is `owned ` and the current broker is indeed the owner, the command completes. Unhappy cases: - If the ownership state is `owned ` and the current broker is not the owner, the command fails (the broker returns an error to the client), and the client tries to find the true new owner by lookups. The global bundle state channel is eventually consistent, and the lookups should eventually converge. - if the ownership change is still in progress(`releasing`, `assigning`), this check will be deferred until the state becomes `owned` with a timeout. > Regards, > Penghui > > On Wed, Aug 2, 2023 at 1:18 AM Heesung Sohn > <heesung.s...@streamnative.io.invalid> wrote: > > > Hi, > > > > It has been over three weeks since this discussion started, and I replied > > to the questions in the PIP. > > I will send out a vote email tomorrow if looking good. > > > > Thanks, > > Heesung > > > > On Tue, Jul 25, 2023 at 1:12 PM Heesung Sohn < > heesung.s...@streamnative.io > > > > > wrote: > > > > > Hi, > > > > > > I replied to the comments from Kai and Ran in the PIP. > > > > > > Please review the PIP by any chance. > > > > > > Thank you, > > > Heesung > > > > > > On Thu, Jul 6, 2023 at 4:32 PM Heesung Sohn < > > heesung.s...@streamnative.io> > > > wrote: > > > > > >> Hi dev, > > >> > > >> I proposed this PIP, https://github.com/apache/pulsar/pull/20748, to > > >> make unloaded clients directly and gracefully connect to new owner > > brokers > > >> without lookups. > > >> > > >> Please take a look and let me know what you think. > > >> > > >> Regards, > > >> Heesung > > >> > > > > > >
