Hi Jun,
Thanks for pointing it out. It makes sense to me. We can have the following
metrics instead. What do you think?
- remote-(fetch|copy)-throttle-time-avg (The average time in ms remote
fetches/copies was throttled by a broker)
- remote-(fetch|copy)-throttle-time--max (The maximum time in ms remote
fetches/copies was throttled by a broker)
These are similar to fetch-throttle-time-avg and fetch-throttle-time-max
metrics we have for Kafak Consumers?
The Avg and Max are computed over the (sliding) window as defined by the
configuration metrics.sample.window.ms on the server.
(Also, I will update the config and metric names to be consistent)
Regards.
On Thu, Feb 29, 2024 at 2:51 AM Jun Rao <j...@confluent.io.invalid> wrote:
> Hi, Abhijeet,
>
> Thanks for the reply.
>
> The issue with recording the throttle time as a gauge is that it's
> transient. If the metric is not read immediately, the recorded value could
> be reset to 0. The admin won't realize that throttling has happened.
>
> For client quotas, the throttle time is tracked as the average
> throttle-time per user/client-id. This makes the metric less transient.
>
> Also, the configs use read/write whereas the metrics use fetch/copy. Could
> we make them consistent?
>
> Jun
>
> On Wed, Feb 28, 2024 at 6:49 AM Abhijeet Kumar <abhijeet.cse....@gmail.com
> >
> wrote:
>
> > Hi Jun,
> >
> > Clarified the meaning of the two metrics. Also updated the KIP.
> >
> > kafka.log.remote:type=RemoteLogManager, name=RemoteFetchThrottleTime ->
> The
> > duration of time required at a given moment to bring the observed fetch
> > rate within the allowed limit, by preventing further reads.
> > kafka.log.remote:type=RemoteLogManager, name=RemoteCopyThrottleTime ->
> The
> > duration of time required at a given moment to bring the observed remote
> > copy rate within the allowed limit, by preventing further copies.
> >
> > Regards.
> >
> > On Wed, Feb 28, 2024 at 12:28 AM Jun Rao <j...@confluent.io.invalid>
> wrote:
> >
> > > Hi, Abhijeet,
> > >
> > > Thanks for the explanation. Makes sense to me now.
> > >
> > > Just a minor comment. Could you document the exact meaning of the
> > following
> > > two metrics? For example, is the time accumulated? If so, is it from
> the
> > > start of the broker or over some window?
> > >
> > > kafka.log.remote:type=RemoteLogManager, name=RemoteFetchThrottleTime
> > > kafka.log.remote:type=RemoteLogManager, name=RemoteCopyThrottleTime
> > >
> > > Jun
> > >
> > > On Tue, Feb 27, 2024 at 1:39 AM Abhijeet Kumar <
> > abhijeet.cse....@gmail.com
> > > >
> > > wrote:
> > >
> > > > Hi Jun,
> > > >
> > > > The existing quota system for consumers is designed to throttle the
> > > > consumer if it exceeds the allowed fetch rate.
> > > > The additional quota we want to add works on the broker level. If the
> > > > broker-level remote read quota is being
> > > > exceeded, we prevent additional reads from the remote storage but do
> > not
> > > > prevent local reads for the consumer.
> > > > If the consumer has specified other partitions to read, which can be
> > > served
> > > > from local, it can continue to read those
> > > > partitions. To elaborate more, we make a check for quota exceeded if
> we
> > > > know a segment needs to be read from
> > > > remote. If the quota is exceeded, we simply skip the partition and
> move
> > > to
> > > > other segments in the fetch request.
> > > > This way consumers can continue to read the local data as long as
> they
> > > have
> > > > not exceeded the client-level quota.
> > > >
> > > > Also, when we choose the appropriate consumer-level quota, we would
> > > > typically look at what kind of local fetch
> > > > throughput is supported. If we were to reuse the same consumer quota,
> > we
> > > > should also consider the throughput
> > > > the remote storage supports. The throughput supported by remote may
> be
> > > > less/more than the throughput supported
> > > > by local (when using a cloud provider, it depends on the plan opted
> by
> > > the
> > > > user). The consumer quota has to be carefully
> > > > set considering both local and remote throughput. Instead, if we
> have a
> > > > separate quota, it makes things much simpler
> > > > for the user, since they already know what throughput their remote
> > > storage
> > > > supports.
> > > >
> > > > (Also, thanks for pointing out. I will update the KIP based on the
> > > > discussion)
> > > >
> > > > Regards,
> > > > Abhijeet.
> > > >
> > > > On Tue, Feb 27, 2024 at 2:49 AM Jun Rao <j...@confluent.io.invalid>
> > > wrote:
> > > >
> > > > > Hi, Abhijeet,
> > > > >
> > > > > Sorry for the late reply. It seems that you haven't updated the KIP
> > > based
> > > > > on the discussion? One more comment.
> > > > >
> > > > > 11. Currently, we already have a quota system for both the
> producers
> > > and
> > > > > consumers. I can understand why we need an additional
> > > > > remote.log.manager.write.quota.default quota. For example, when
> tier
> > > > > storage is enabled for the first time, there could be a lot of
> > segments
> > > > > that need to be written to the remote storage, even though there is
> > no
> > > > > increase in the produced data. However, I am not sure about an
> > > > > additional remote.log.manager.read.quota.default. The KIP says that
> > the
> > > > > reason is "This may happen when the majority of the consumers start
> > > > reading
> > > > > from the earliest offset of their respective Kafka topics.".
> However,
> > > > this
> > > > > can happen with or without tier storage and the current quota
> system
> > > for
> > > > > consumers is designed for solving this exact problem. Could you
> > explain
> > > > the
> > > > > usage of this additional quota?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Jun
> > > > >
> > > > > On Mon, Feb 12, 2024 at 11:08 AM Abhijeet Kumar <
> > > > > abhijeet.cse....@gmail.com>
> > > > > wrote:
> > > > >
> > > > > > Comments inline
> > > > > >
> > > > > > On Wed, Dec 6, 2023 at 1:12 AM Jun Rao <j...@confluent.io.invalid
> >
> > > > wrote:
> > > > > >
> > > > > > > Hi, Abhijeet,
> > > > > > >
> > > > > > > Thanks for the KIP. A few comments.
> > > > > > >
> > > > > > > 10. remote.log.manager.write.quota.default:
> > > > > > > 10.1 For other configs, we
> > > > > > > use replica.alter.log.dirs.io.max.bytes.per.second. To be
> > > consistent,
> > > > > > > perhaps this can be sth like
> > > > > > remote.log.manager.write.max.bytes.per.second.
> > > > > > >
> > > > > >
> > > > > > This makes sense, we can rename the following configs to be
> > > consistent.
> > > > > >
> > > > > > Remote.log.manager.write.quota.default ->
> > > > > > remote.log.manager.write.max.bytes.per.second
> > > > > >
> > > > > > Remote.log.manager.read.quota.default ->
> > > > > > remote.log.manager.read.max.bytes.per.second.
> > > > > >
> > > > > >
> > > > > >
> > > > > > > 10.2 Could we list the new metrics associated with the new
> quota.
> > > > > > >
> > > > > >
> > > > > > We will add the following metrics as mentioned in the other
> > response.
> > > > > > *RemoteFetchThrottleTime* - The amount of time needed to bring
> the
> > > > > observed
> > > > > > remote fetch rate within the read quota
> > > > > > *RemoteCopyThrottleTime *- The amount of time needed to bring the
> > > > > observed
> > > > > > remote copy rate with the copy quota.
> > > > > >
> > > > > > 10.3 Is this dynamically configurable? If so, could we document
> the
> > > > > impact
> > > > > > > to tools like kafka-configs.sh and AdminClient?
> > > > > > >
> > > > > >
> > > > > > Yes, the quotas are dynamically configurable. We will add them as
> > > > Dynamic
> > > > > > Broker Configs. Users will be able to change
> > > > > > the following configs using either kafka-configs.sh or
> AdminClient
> > by
> > > > > > specifying the config name and new value. For eg.
> > > > > >
> > > > > > Using kafka-configs.sh
> > > > > >
> > > > > > bin/kafka-configs.sh --bootstrap-server <bootstrap-server>
> > > > --entity-type
> > > > > > brokers --entity-default --alter --add-config
> > > > > > remote.log.manager.write.max.bytes.per.second=52428800
> > > > > >
> > > > > > Using AdminClient
> > > > > >
> > > > > > ConfigEntry configEntry = new
> > > > > > ConfigEntry("remote.log.manager.write.max.bytes.per.second",
> > > > "5242800");
> > > > > > AlterConfigOp alterConfigOp = new AlterConfigOp(configEntry,
> > > > > > AlterConfigOp.OpType.SET);
> > > > > > List<AlterConfigOp> alterConfigOps =
> > > > > > Collections.singletonList(alterConfigOp);
> > > > > >
> > > > > > ConfigResource resource = new
> > > > ConfigResource(ConfigResource.Type.BROKER,
> > > > > > "");
> > > > > > Map<ConfigResource, Collection<AlterConfigOp>> updateConfig =
> > > > > > ImmutableMap.of(resource, alterConfigOps);
> > > > > > adminClient.incrementalAlterConfigs(updateConfig);
> > > > > >
> > > > > >
> > > > > > >
> > > > > > > Jun
> > > > > > >
> > > > > > > On Tue, Nov 28, 2023 at 2:19 AM Luke Chen <show...@gmail.com>
> > > wrote:
> > > > > > >
> > > > > > > > Hi Abhijeet,
> > > > > > > >
> > > > > > > > Thanks for the KIP!
> > > > > > > > This is an important feature for tiered storage.
> > > > > > > >
> > > > > > > > Some comments:
> > > > > > > > 1. Will we introduce new metrics for this tiered storage
> > quotas?
> > > > > > > > This is important because the admin can know the throttling
> > > status
> > > > by
> > > > > > > > checking the metrics while the remote write/read are slow,
> like
> > > the
> > > > > > rate
> > > > > > > of
> > > > > > > > uploading/reading byte rate, the throttled time for
> > > upload/read...
> > > > > etc.
> > > > > > > >
> > > > > > > > 2. Could you give some examples for the throttling algorithm
> in
> > > the
> > > > > KIP
> > > > > > > to
> > > > > > > > explain it? That will make it much clearer.
> > > > > > > >
> > > > > > > > 3. To solve this problem, we can break down the RLMTask into
> > two
> > > > > > smaller
> > > > > > > > tasks - one for segment upload and the other for handling
> > expired
> > > > > > > segments.
> > > > > > > > How do we handle the situation when a segment is still
> waiting
> > > for
> > > > > > > > offloading while this segment is expired and eligible to be
> > > > deleted?
> > > > > > > > Maybe it'll be easier to not block the RLMTask when quota
> > > exceeded,
> > > > > and
> > > > > > > > just check it each time the RLMTask runs?
> > > > > > > >
> > > > > > > > Thank you.
> > > > > > > > Luke
> > > > > > > >
> > > > > > > > On Wed, Nov 22, 2023 at 6:27 PM Abhijeet Kumar <
> > > > > > > abhijeet.cse....@gmail.com
> > > > > > > > >
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > Hi All,
> > > > > > > > >
> > > > > > > > > I have created KIP-956 for defining read and write quota
> for
> > > > tiered
> > > > > > > > > storage.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-956+Tiered+Storage+Quotas
> > > > > > > > >
> > > > > > > > > Feedback and suggestions are welcome.
> > > > > > > > >
> > > > > > > > > Regards,
> > > > > > > > > Abhijeet.
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Abhijeet.
> > > > > >
> > > > >
> > > >
> > > >
> > > > --
> > > > Abhijeet.
> > > >
> > >
> >
> >
> > --
> > Abhijeet.
> >
>
--
Abhijeet.
