Hi, Colin,
First, since we are changing the format of LeaderAndIsrRequest, which is an
inter broker request, it seems that we will need IBP during rolling
upgrade. Could we add that to the compatibility section?
Regarding UnsupportedVersionException, even without ZK node version bump,
we probably want to only use the new ZK value fields after all brokers have
been upgraded to the new binary. Otherwise, the reassignment task may not
be completed if the controller changes to a broker still on the old binary.
IBP is one way to achieve that. The main thing is that we need some way for
the controller to deal with the new ZK fields. Dealing with the additional
ZK node version bump seems a small thing on top of that?
Thanks,
Jun
On Thu, Aug 1, 2019 at 3:05 PM Colin McCabe <cmcc...@apache.org> wrote:
> On Thu, Aug 1, 2019, at 12:00, Jun Rao wrote:
> > Hi, Colin,
> >
> > 10. Sounds good.
> >
> > 13. Our current convention is to bump up the version of ZK value if there
> > is any format change. For example, we have bumped up the version of the
> > value in /brokers/ids/nnn multiple times and all of those changes are
> > compatible (just adding new fields). This has the slight benefit that it
> > makes it clear there is a format change. Rolling upgrades and downgrades
> > can still be supported with the version bump. For example, if you
> downgrade
> > from a compatible change, you can leave the new format in ZK and the old
> > code will only pick up fields relevant to the old version. Upgrade will
> be
> > controlled by inter broker protocol.
>
> Hmm. If we bump that ZK node version, we will need a new inter-broker
> protocol version. We also need to return UnsupportedVersionException from
> the alterPartitionReassignments and listPartitionReassignments APIs when
> the IBP is too low. This sounds doable, although we might need a release
> note that upgrading the IBP is necessary to allow reassignment operations
> after an upgrade.
>
> best,
> Colin
>
> >
> > Thanks,
> >
> > Jun
> >
> > On Wed, Jul 31, 2019 at 1:22 PM Colin McCabe <cmcc...@apache.org> wrote:
> >
> > > Hi Jun,
> > >
> > > Thanks for taking another look at this.
> > >
> > > On Wed, Jul 31, 2019, at 09:22, Jun Rao wrote:
> > > > Hi, Stan,
> > > >
> > > > Thanks for the explanation.
> > > >
> > > > 10. If those new fields in LeaderAndIsr are only needed for future
> work,
> > > > perhaps they should be added when we do the future work instead of
> now?
> > >
> > > I think this ties in with one of the big goals of this KIP, making it
> > > possible to distinguish reassigning replicas from normal replicas.
> This is
> > > the key to follow-on work like being able to ensure that partitions
> with a
> > > reassignment don't get falsely flagged as under-replicated in the
> metrics,
> > > or implementing reassignment quotas that don't accidentally affect
> normal
> > > replication traffic when a replica falls out of the ISR.
> > >
> > > For these follow-on improvements, we need to have that information in
> > > LeaderAndIsrRequest. We could add the information in a follow-on KIP,
> of
> > > course, but then all the improvements are blocked on that follow-on
> KIP.
> > > That would slow things down for all of the downstream KIPs that are
> blocked
> > > on this.
> > >
> > > Also, to keep things consistent, I think it would be best if the
> format of
> > > the data in the LeaderAndIsrRequest matched the format of the data in
> > > ZooKeeper. Since we're deciding on the ZK format in this KIP, I think
> it
> > > makes sense to also decide on the format in the LeaderAndIsrRequest.
> > >
> > > > > > Should we include those two fields in UpdateMetadata and
> potentially
> > > > > > Metadata requests too?
> > >
> > > We had some discussion earlier about how metadata responses to clients
> are
> > > getting too large, in part because they include a lot of information
> that
> > > most clients don't need (such as the ISR). I think reassignment
> > > information definitely falls in the category of something a client
> doesn't
> > > need to know, so we shouldn't include it.
> > >
> > > A program like CruiseControl, or the command-line reassignment program,
> > > just wants to get the most up-to-date information about the state of
> > > reassigning partitions. The MetadataRequest API wouldn't deliver that,
> > > because there are inherently delays in how we propagate metadata to
> > > brokers. That's why the ListPartitionReassignments API is a better
> choice
> > > for those programs. So I think if we added this information to the
> > > MetadataResponse, nobody would actually use it, and it would just use
> up
> > > more bandwidth.
> > >
> > > Of course, we can always revisit this later if we find a scenario
> where a
> > > producer or consumer would actually care about this. But I think we
> should
> > > default to not adding stuff to the metadata response if we don't have a
> > > good use case in mind.
> > >
> > > > > > 11. "If a new reassignment is issued during an on-going one, we
> > > cancel the
> > > > > > current one by emptying out both AR and RR, constructing them
> from
> > > (the
> > > > > > updated from the last-reassignment) R and TR, and starting
> anew." In
> > > this
> > > > > > case, it seems that the controller needs to issue a StopReplica
> > > request to
> > > > > > remove those unneeded replicas.
> > >
> > > Good catch. Yes, we should document this in the KIP.
> > >
> > > > > > 12. "Essentially, once a cancellation is called we subtract AR
> from
> > > R,
> > > > > > empty out both AR and RR, and send LeaderAndIsr requests to
> cancel
> > > the
> > > > > > replica movements that have not yet completed." Similar to the
> > > above, it
> > > > > > seems the controller needs to issue a StopReplica request to
> remove
> > > those
> > > > > > unneeded replicas.
> > >
> > > Right. Let's add this.
> > >
> > > > > > 13. Since we changed the format of the topics/[topic] zNode,
> should
> > > we bump
> > > > > > up the version number in the json value?
> > >
> > > The change to the zNode is backwards compatible, though. Older brokers
> > > will continue to work, but just ignore the new fields. If we bump that
> > > version number, then downgrades will require hand-editing zookeeper.
> (Of
> > > course downgrade isn't officially supported, but it would be nice not
> to
> > > break it if we don't need to...) Changing the version number would
> also
> > > create problems during a rolling upgrade.
> > >
> > > best,
> > > Colin
> > >
> > > > > >
> > > > > > Jun
> > > > > >
> > > > > > On Mon, Jul 22, 2019 at 8:38 AM Colin McCabe <cmcc...@apache.org
> >
> > > wrote:
> > > > > >
> > > > > > > Hi all,
> > > > > > >
> > > > > > > With three non-binding +1 votes from Viktor Somogyi-Vass,
> Robert
> > > > > Barrett,
> > > > > > > and George Li, and 3 binding +1 votes from Gwen Shapira, Jason
> > > > > Gustafson,
> > > > > > > and myself, the vote passes. Thanks, everyone!
> > > > > > >
> > > > > > > best,
> > > > > > > Colin
> > > > > > >
> > > > > > > On Fri, Jul 19, 2019, at 08:55, Robert Barrett wrote:
> > > > > > > > +1 (non-binding). Thanks for the KIP!
> > > > > > > >
> > > > > > > > On Thu, Jul 18, 2019 at 5:59 PM George Li <
> > > sql_consult...@yahoo.com
> > > > > > > .invalid>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > +1 (non-binding)
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Thanks for addressing the comments.
> > > > > > > > > George
> > > > > > > > >
> > > > > > > > > On Thursday, July 18, 2019, 05:03:58 PM PDT, Gwen
> Shapira <
> > > > > > > > > g...@confluent.io> wrote:
> > > > > > > > >
> > > > > > > > > Renewing my +1, thank you Colin and Stan for working
> through
> > > all
> > > > > the
> > > > > > > > > questions, edge cases, requests and alternatives. We ended
> up
> > > with
> > > > > a
> > > > > > > > > great protocol.
> > > > > > > > >
> > > > > > > > > On Thu, Jul 18, 2019 at 4:54 PM Jason Gustafson <
> > > > > ja...@confluent.io>
> > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > +1 Thanks for the KIP. Really looking forward to this!
> > > > > > > > > >
> > > > > > > > > > -Jason
> > > > > > > > > >
> > > > > > > > > > On Wed, Jul 17, 2019 at 1:41 PM Colin McCabe <
> > > cmcc...@apache.org
> > > > > >
> > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > > Thanks, Stanislav. Let's restart the vote to reflect
> the
> > > fact
> > > > > > that
> > > > > > > > > we've
> > > > > > > > > > > made significant changes. The new vote will go for 3
> days
> > > as
> > > > > > > usual.
> > > > > > > > > > >
> > > > > > > > > > > I'll start with my +1 (binding).
> > > > > > > > > > >
> > > > > > > > > > > best,
> > > > > > > > > > > Colin
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > On Wed, Jul 17, 2019, at 08:56, Stanislav Kozlovski
> wrote:
> > > > > > > > > > > > Hey everybody,
> > > > > > > > > > > >
> > > > > > > > > > > > We have further iterated on the KIP in the
> accompanying
> > > > > > > discussion
> > > > > > > > > thread
> > > > > > > > > > > > and I'd like to propose we resume the vote.
> > > > > > > > > > > >
> > > > > > > > > > > > Some notable changes:
> > > > > > > > > > > > - we will store reassignment information in the
> > > > > > > > > `/brokers/topics/[topic]`
> > > > > > > > > > > > - we will internally use two collections to
> represent a
> > > > > > > reassignment
> > > > > > > > > -
> > > > > > > > > > > > "addingReplicas" and "removingReplicas".
> LeaderAndIsr has
> > > > > been
> > > > > > > > > updated
> > > > > > > > > > > > accordingly
> > > > > > > > > > > > - the Alter API will still use the "targetReplicas"
> > > > > collection,
> > > > > > > but
> > > > > > > > > the
> > > > > > > > > > > > List API will now return three separate collections
> - the
> > > > > full
> > > > > > > > > replica
> > > > > > > > > > > set,
> > > > > > > > > > > > the replicas we are adding as part of this
> reassignment
> > > > > > > > > > > ("addingReplicas")
> > > > > > > > > > > > and the replicas we are removing ("removingReplicas")
> > > > > > > > > > > > - cancellation of a reassignment now means a proper
> > > rollback
> > > > > of
> > > > > > > the
> > > > > > > > > > > > assignment to its original state prior to the API
> call
> > > > > > > > > > > >
> > > > > > > > > > > > As always, you can re-read the KIP here
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-455%3A+Create+an+Administrative+API+for+Replica+Reassignment
> > > > > > > > > > > >
> > > > > > > > > > > > Best,
> > > > > > > > > > > > Stanislav
> > > > > > > > > > > >
> > > > > > > > > > > > On Wed, May 22, 2019 at 6:12 PM Colin McCabe <
> > > > > > cmcc...@apache.org
> > > > > > > >
> > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > > Hi George,
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks for taking a look. I am working on getting
> a PR
> > > > > done
> > > > > > > as a
> > > > > > > > > > > > > proof-of-concept. I'll post it soon. Then we'll
> > > finish up
> > > > > > the
> > > > > > > > > vote.
> > > > > > > > > > > > >
> > > > > > > > > > > > > best,
> > > > > > > > > > > > > Colin
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Tue, May 21, 2019, at 17:33, George Li wrote:
> > > > > > > > > > > > > > Hi Colin,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Great! Looking forward to these features. +1
> > > > > > > (non-binding)
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > What is the estimated timeline to have this
> > > implemented?
> > > > > > If
> > > > > > > any
> > > > > > > > > help
> > > > > > > > > > > > > > is needed in the implementation of cancelling
> > > > > > > reassignments, I
> > > > > > > > > can
> > > > > > > > > > > > > > help if there is spare cycle.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > George
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Thursday, May 16, 2019, 9:48:56 AM PDT,
> Colin
> > > > > McCabe
> > > > > > > > > > > > > > <cmcc...@apache.org> wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Hi George,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Yes, KIP-455 allows the reassignment of
> individual
> > > > > > > partitions to
> > > > > > > > > be
> > > > > > > > > > > > > > cancelled. I think it's very important for these
> > > > > > operations
> > > > > > > to
> > > > > > > > > be at
> > > > > > > > > > > > > > the partition level.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > best,
> > > > > > > > > > > > > > Colin
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Tue, May 14, 2019, at 16:34, George Li wrote:
> > > > > > > > > > > > > > > Hi Colin,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks for the updated KIP. It has very good
> > > > > > improvements
> > > > > > > of
> > > > > > > > > Kafka
> > > > > > > > > > > > > > > reassignment operations.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > One question, looks like the KIP includes the
> > > > > > Cancellation
> > > > > > > of
> > > > > > > > > > > > > > > individual pending reassignments as well when
> the
> > > > > > > > > > > > > > > AlterPartitionReasisgnmentRequest has empty
> > > replicas
> > > > > for
> > > > > > > the
> > > > > > > > > > > > > > > topic/partition. Will you also be implementing
> the
> > > the
> > > > > > > > > partition
> > > > > > > > > > > > > > > cancellation/rollback in the PR ? If yes,
> it
> > > will
> > > > > > make
> > > > > > > > > KIP-236
> > > > > > > > > > > (it
> > > > > > > > > > > > > > > has PR already) trivial, since the cancel all
> > > pending
> > > > > > > > > > > reassignments,
> > > > > > > > > > > > > > > one just needs to do a
> > > ListPartitionRessignmentRequest,
> > > > > > > then
> > > > > > > > > submit
> > > > > > > > > > > > > > > empty replicas for all those topic/partitions
> in
> > > > > > > > > > > > > > > one AlterPartitionReasisgnmentRequest.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > George
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Friday, May 10, 2019, 8:44:31 PM PDT,
> Colin
> > > > > McCabe
> > > > > > > > > > > > > > > <cmcc...@apache.org> wrote:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Fri, May 10, 2019, at 17:34, Colin McCabe
> > > wrote:
> > > > > > > > > > > > > > > > On Fri, May 10, 2019, at 16:43, Jason
> Gustafson
> > > > > wrote:
> > > > > > > > > > > > > > > > > Hi Colin,
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I think storing reassignment state at the
> > > partition
> > > > > > > level
> > > > > > > > > is
> > > > > > > > > > > the
> > > > > > > > > > > > > right move
> > > > > > > > > > > > > > > > > and I also agree that replicas should
> > > understand
> > > > > that
> > > > > > > > > there is
> > > > > > > > > > > a
> > > > > > > > > > > > > > > > > reassignment in progress. This makes
> KIP-352 a
> > > > > > trivial
> > > > > > > > > > > follow-up
> > > > > > > > > > > > > for
> > > > > > > > > > > > > > > > > example. The only doubt I have is whether
> the
> > > > > leader
> > > > > > > and
> > > > > > > > > isr
> > > > > > > > > > > znode
> > > > > > > > > > > > > is the
> > > > > > > > > > > > > > > > > right place to store the target
> reassignment.
> > > It
> > > > > is a
> > > > > > > bit
> > > > > > > > > odd
> > > > > > > > > > > to
> > > > > > > > > > > > > keep the
> > > > > > > > > > > > > > > > > target assignment in a separate place from
> the
> > > > > > current
> > > > > > > > > > > assignment,
> > > > > > > > > > > > > right? I
> > > > > > > > > > > > > > > > > assume the thinking is probably that
> although
> > > the
> > > > > > > current
> > > > > > > > > > > > > assignment should
> > > > > > > > > > > > > > > > > probably be in the leader and isr znode as
> > > well, it
> > > > > > is
> > > > > > > > > hard to
> > > > > > > > > > > > > move the
> > > > > > > > > > > > > > > > > state in a compatible way. Is that right?
> But
> > > if we
> > > > > > > have no
> > > > > > > > > > > plan
> > > > > > > > > > > > > to remove
> > > > > > > > > > > > > > > > > the assignment znode, do you see a
> downside to
> > > > > > storing
> > > > > > > the
> > > > > > > > > > > target
> > > > > > > > > > > > > > > > > assignment there as well?
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Hi Jason,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > That's a good point -- it's probably better
> to
> > > keep
> > > > > the
> > > > > > > > > target
> > > > > > > > > > > > > > > > assignment in the same znode as the current
> > > > > assignment,
> > > > > > > for
> > > > > > > > > > > > > > > > consistency. I'll change the KIP.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi Jason,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks again for the review.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I took another look at this, and I think we
> should
> > > > > stick
> > > > > > > with
> > > > > > > > > the
> > > > > > > > > > > > > > > initial proposal of putting the reassignment
> state
> > > into
> > > > > > > > > > > > > > >
> > > /brokers/topics/[topic]/partitions/[partitionId]/state.
> > > > > > > The
> > > > > > > > > > > reason is
> > > > > > > > > > > > > > > because we'll want to bump the leader epoch
> for the
> > > > > > > partition
> > > > > > > > > when
> > > > > > > > > > > > > > > changing the reassignment state, and the leader
> > > epoch
> > > > > > > resides
> > > > > > > > > in
> > > > > > > > > > > that
> > > > > > > > > > > > > > > znode anyway. I agree there is some
> inconsistency
> > > > > here,
> > > > > > > but
> > > > > > > > > so be
> > > > > > > > > > > it:
> > > > > > > > > > > > > > > if we were to greenfield these zookeeper data
> > > > > structures,
> > > > > > > we
> > > > > > > > > might
> > > > > > > > > > > do
> > > > > > > > > > > > > > > it differently, but the proposed scheme will
> work
> > > fine
> > > > > > and
> > > > > > > be
> > > > > > > > > > > > > > > extensible for the future.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > A few additional questions:
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 1. Should `alterPartitionReassignments` be
> > > > > > > > > > > > > `alterPartitionAssignments`?
> > > > > > > > > > > > > > > > > It's the current assignment we're altering,
> > > right?
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > That's fair. AlterPartitionAssigments reads
> a
> > > little
> > > > > > > > > better, and
> > > > > > > > > > > > > I'll
> > > > > > > > > > > > > > > > change it to that.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > +1. I've changed the RPC and API name in the
> wiki.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 2. Does this change affect the Metadata
> API? In
> > > > > other
> > > > > > > > > words,
> > > > > > > > > > > are
> > > > > > > > > > > > > clients
> > > > > > > > > > > > > > > > > aware of reassignments? If so, then we
> probably
> > > > > need
> > > > > > a
> > > > > > > > > change
> > > > > > > > > > > to
> > > > > > > > > > > > > > > > > UpdateMetadata as well. The only
> alternative I
> > > can
> > > > > > > think of
> > > > > > > > > > > would
> > > > > > > > > > > > > be to
> > > > > > > > > > > > > > > > > represent the replica set in the Metadata
> > > request
> > > > > as
> > > > > > > the
> > > > > > > > > union
> > > > > > > > > > > of
> > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > > current and target replicas, but I can't
> think
> > > of
> > > > > any
> > > > > > > > > benefit
> > > > > > > > > > > to
> > > > > > > > > > > > > hiding
> > > > > > > > > > > > > > > > > reassignments. Note that if we did this, we
> > > > > probably
> > > > > > > > > wouldn't
> > > > > > > > > > > need
> > > > > > > > > > > > > a
> > > > > > > > > > > > > > > > > separate API to list reassignments.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > I thought about this a bit... and I think on
> > > balance,
> > > > > > > you're
> > > > > > > > > > > right.
> > > > > > > > > > > > > We
> > > > > > > > > > > > > > > > should keep this information together with
> the
> > > > > replica
> > > > > > > > > nodes, isr
> > > > > > > > > > > > > > > > nodes, and offline replicas, and that
> > > information is
> > > > > > > > > available in
> > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > MetadataResponse.
> > > > > > > > > > > > > > > > However, I do think in order to do this,
> we'll
> > > need
> > > > > a
> > > > > > > flag
> > > > > > > > > in
> > > > > > > > > > > the
> > > > > > > > > > > > > > > > MetadataRequest that specifiies "only show me
> > > > > > reassigning
> > > > > > > > > > > > > partitions".
> > > > > > > > > > > > > > > > I'll add this.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I revisited this, and I think we should stick
> with
> > > the
> > > > > > > original
> > > > > > > > > > > > > > > proposal of having a separate
> > > > > ListPartitionReassignments
> > > > > > > API.
> > > > > > > > > > > There
> > > > > > > > > > > > > > > really is no use case where the Producer or
> > > Consumer
> > > > > > needs
> > > > > > > to
> > > > > > > > > know
> > > > > > > > > > > > > > > about a reassignment. They should just be
> notified
> > > > > when
> > > > > > > the
> > > > > > > > > set of
> > > > > > > > > > > > > > > partitions changes, which doesn't require
> changes
> > > to
> > > > > > > > > > > > > > > MetadataRequest/Response. The Admin client
> only
> > > cares
> > > > > if
> > > > > > > > > someone
> > > > > > > > > > > is
> > > > > > > > > > > > > > > managing the reassignment. So adding this
> state
> > > to the
> > > > > > > > > > > > > > > MetadataResponse adds overhead for no real
> > > benefit. In
> > > > > > the
> > > > > > > > > common
> > > > > > > > > > > > > case
> > > > > > > > > > > > > > > where there is no ongoing reassignment, it
> would
> > > be 4
> > > > > > > bytes per
> > > > > > > > > > > > > > > partition of extra overhead in the
> > > MetadataResponse.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > In general, I think we have a problem of
> > > oversharing in
> > > > > > the
> > > > > > > > > > > > > > > MetadataRequest/Response. As we 10x or 100x
> the
> > > number
> > > > > > of
> > > > > > > > > > > partitions
> > > > > > > > > > > > > > > we support, we'll need to get stricter about
> giving
> > > > > > clients
> > > > > > > > > only
> > > > > > > > > > > the
> > > > > > > > > > > > > > > information they actually need, about the
> > > partitions
> > > > > they
> > > > > > > > > actually
> > > > > > > > > > > > > care
> > > > > > > > > > > > > > > about. Reassignment state clearly falls in the
> > > > > category
> > > > > > of
> > > > > > > > > state
> > > > > > > > > > > that
> > > > > > > > > > > > > > > isn't needed by clients (except very
> specialized
> > > > > > > rebalancing
> > > > > > > > > > > programs).
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Another important consideration here is that
> > > someone
> > > > > > > managing
> > > > > > > > > an
> > > > > > > > > > > > > > > ongoing reassignment wants the most up-to-date
> > > > > > information,
> > > > > > > > > which
> > > > > > > > > > > is
> > > > > > > > > > > > > to
> > > > > > > > > > > > > > > be found on the controller. Therefore adding
> this
> > > > > state
> > > > > > to
> > > > > > > > > > > listTopics
> > > > > > > > > > > > > > > or describeTopics, which could contact any
> node in
> > > the
> > > > > > > > > cluster, is
> > > > > > > > > > > > > > > sub-optimal.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Finally, adding this to listTopics or
> > > describeTopics
> > > > > > feels
> > > > > > > > > like a
> > > > > > > > > > > > > warty
> > > > > > > > > > > > > > > API. It's an extra boolean which interacts
> with
> > > other
> > > > > > > extra
> > > > > > > > > > > booleans
> > > > > > > > > > > > > > > like "show internal", etc. in weird ways. I
> think
> > > a
> > > > > > > separate
> > > > > > > > > API
> > > > > > > > > > > is
> > > > > > > > > > > > > > > cleaner.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 3. As replicas come into sync, they will
> join
> > > the
> > > > > > ISR.
> > > > > > > > > Will we
> > > > > > > > > > > > > await all
> > > > > > > > > > > > > > > > > target replicas joining the ISR before
> taking
> > > the
> > > > > > > replica
> > > > > > > > > out
> > > > > > > > > > > of
> > > > > > > > > > > > > the target
> > > > > > > > > > > > > > > > > replicas set? Also, I assume that target
> > > replicas
> > > > > can
> > > > > > > > > still be
> > > > > > > > > > > > > elected as
> > > > > > > > > > > > > > > > > leader?
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > We'll take a replica out of the target
> replicas
> > > set
> > > > > as
> > > > > > > soon
> > > > > > > > > as
> > > > > > > > > > > that
> > > > > > > > > > > > > > > > replica is in the ISR. Let me clarify this
> in
> > > the
> > > > > KIP.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 4. Probably useful to mention permissions
> for
> > > the
> > > > > new
> > > > > > > APIs.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Good point. I think
> alterPartitionAssignments
> > > should
> > > > > > > require
> > > > > > > > > > > ALTER
> > > > > > > > > > > > > on
> > > > > > > > > > > > > > > > CLUSTER. MetadataRequest permissions will be
> > > > > > unchanged.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I added permission information.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > best,
> > > > > > > > > > > > > > > Colin
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > best,
> > > > > > > > > > > > > > > > Colin
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > > > Jason
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > On Fri, May 10, 2019 at 9:30 AM Gwen
> Shapira <
> > > > > > > > > > > g...@confluent.io>
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > +1 (binding)
> > > > > > > > > > > > > > > > > > Looks great, and will be awesome to have
> > > this new
> > > > > > > > > capability.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > On Wed, May 8, 2019 at 10:23 PM Colin
> McCabe
> > > <
> > > > > > > > > > > cmcc...@apache.org>
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Hi all,
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > I'd like to start the vote for KIP-455:
> > > Create
> > > > > an
> > > > > > > > > > > > > Administrative API for
> > > > > > > > > > > > > > > > > > > Replica Reassignment. I think this
> KIP is
> > > > > > > important
> > > > > > > > > since
> > > > > > > > > > > it
> > > > > > > > > > > > > will unlock
> > > > > > > > > > > > > > > > > > > many follow-on improvements to Kafka
> > > > > reassignment
> > > > > > > (see
> > > > > > > > > the
> > > > > > > > > > > > > "Future work"
> > > > > > > > > > > > > > > > > > > section, plus a lot of the other
> > > discussions
> > > > > > we've
> > > > > > > had
> > > > > > > > > > > > > recently about
> > > > > > > > > > > > > > > > > > > reassignment). It also furthers the
> > > important
> > > > > > > KIP-4
> > > > > > > > > goal
> > > > > > > > > > > of
> > > > > > > > > > > > > removing
> > > > > > > > > > > > > > > > > > > direct access to ZK.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > I made a few changes based on the
> > > discussion in
> > > > > > the
> > > > > > > > > > > [DISCUSS]
> > > > > > > > > > > > > thread. As
> > > > > > > > > > > > > > > > > > > Robert suggested, I removed the need to
> > > > > > explicitly
> > > > > > > > > cancel a
> > > > > > > > > > > > > reassignment
> > > > > > > > > > > > > > > > > > > for a partition before setting up a
> > > different
> > > > > > > > > reassignment
> > > > > > > > > > > for
> > > > > > > > > > > > > that
> > > > > > > > > > > > > > > > > > > specific partition. I also simplified
> the
> > > API
> > > > > a
> > > > > > > bit by
> > > > > > > > > > > adding
> > > > > > > > > > > > > a
> > > > > > > > > > > > > > > > > > > PartitionReassignment class which is
> used
> > > by
> > > > > both
> > > > > > > the
> > > > > > > > > alter
> > > > > > > > > > > > > and list
> > > > > > > > > > > > > > > > > > APIs.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > I modified the proposal so that we now
> > > > > deprecate
> > > > > > > the
> > > > > > > > > old
> > > > > > > > > > > > > znode-based API
> > > > > > > > > > > > > > > > > > > rather than removing it completely.
> That
> > > > > should
> > > > > > > give
> > > > > > > > > > > external
> > > > > > > > > > > > > > > > > > rebalancing
> > > > > > > > > > > > > > > > > > > tools some time to transition to the
> new
> > > API.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > To clarify a question Viktor asked, I
> > > added a
> > > > > > note
> > > > > > > > > that the
> > > > > > > > > > > > > > > > > > > kafka-reassign-partitions.sh will now
> use a
> > > > > > > > > > > --bootstrap-server
> > > > > > > > > > > > > argument
> > > > > > > > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > > > contact the admin APIs.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > thanks,
> > > > > > > > > > > > > > > > > > > Colin
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > --
> > > > > > > > > > > > > > > > > > *Gwen Shapira*
> > > > > > > > > > > > > > > > > > Product Manager | Confluent
> > > > > > > > > > > > > > > > > > 650.450.2760 | @gwenshap
> > > > > > > > > > > > > > > > > > Follow us: Twitter <
> > > > > > https://twitter.com/ConfluentInc>
> > > > > > > |
> > > > > > > > > blog
> > > > > > > > > > > > > > > > > > <http://www.confluent.io/blog>
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --
> > > > > > > > > Gwen Shapira
> > > > > > > > > Product Manager | Confluent
> > > > > > > > > 650.450.2760 | @gwenshap
> > > > > > > > > Follow us: Twitter | blog
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
