Hi Kirk, Thanks for your feedback. 1. The clientInstanceId is just a UUID. If client ID is non-null, it's a string and could be quite chunky. I do accept that the change to client ID in this KIP is probably the most contentious part because it's not necessary for the principal intent of this KIP.
2. In Kafka Streams, each of the embedded clients (producer, consumer, admin) will have its own clientInstanceId. There is no separate clientInstanceId for the "logical" client which pulls them together. There could be, but that's not currently part of the KIP. 3. Because clientInstanceId is a tagged field in v2 of the request header, it applies to the latest versions of almost all of the RPCs. If you look at o.a.k.common.message.ApiMessageType.requestHeaderVersion(short), you'll see the mapping. The alternative of defining v3 of the RequestHeader would have necessitated a version bump of every RPC we wanted to have the new header version. Thanks, Andrew On 2026/04/17 23:50:50 Kirk True wrote: > Thanks for the KIP Andrew! > > Some questions: > > 1. Why is it preferable to send the client ID only on the initial request > but the client instance ID on every request? > 2. Are "logical" clients (e.g. Kafka Streams) also assigned a client > instance ID? If so, how does its client instance ID relate to the embedded > clients’ instance IDs? > 3. Is there any advice on "adoption" of the new client instance ID on the > broker side? I could see a situation where some RPCs end up using the client > instance ID, but not others. > Thanks, > Kirk > > On Fri, Apr 3, 2026, at 9:17 AM, Andrew Schofield wrote: > > Hi, > > I would like to start the discussion on KIP-1313. This adds a unique client > > instance ID to the request header of all Kafka protocol requests to give a > > unique identifier which can be used to correlate the requests from each > > client for the purposes of problem determination. > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1313%3A+Client+instance+ID+in+all+request+headers > > > > Thanks, > > Andrew > > >
