On Thu, Jan 25, 2018, at 02:23, Mickael Maison wrote: > I'm late to the party but +1 and thanks for the KIP
Thanks > > On Thu, Jan 25, 2018 at 12:36 AM, Ismael Juma <ism...@juma.me.uk> wrote: > > Agreed, Jun. > > > > Ismael > > > > On Wed, Jan 24, 2018 at 4:08 PM, Jun Rao <j...@confluent.io> wrote: > > > >> Since this is a server side metric, it's probably better to use Yammer Rate > >> (which has count) for consistency. Good point. best, Colin > >> > >> Thanks, > >> > >> Jun > >> > >> On Tue, Jan 23, 2018 at 10:17 PM, Colin McCabe <co...@cmccabe.xyz> wrote: > >> > >> > On Tue, Jan 23, 2018, at 21:47, Ismael Juma wrote: > >> > > Colin, > >> > > > >> > > You get a cumulative count for rates since we added > >> > > https://cwiki.apache.org/confluence/display/KAFKA/KIP- > >> > 187+-+Add+cumulative+count+metric+for+all+Kafka+rate+metrics> > >> > > >> > Oh, good point. > >> > > >> > > >> > > >> > > >> > > Ismael > >> > > > >> > > On Tue, Jan 23, 2018 at 4:21 PM, Colin McCabe > >> > > <cmcc...@apache.org> wrote:> > >> > > > On Tue, Jan 23, 2018, at 11:57, Jun Rao wrote: > >> > > > > Hi, Collin, > >> > > > > > >> > > > > Thanks for the updated KIP. +1. Just a minor comment. It seems > >> > > > > that it's> > > better for TotalIncrementalFetchSessionsEvicted to > >> > be a rate, > >> > > > > instead of> > > just an ever-growing count. > >> > > > > >> > > > Thanks. Perhaps we can add the rate in addition to the total > >> > > > eviction> > count? > >> > > > > >> > > > best, > >> > > > Colin > >> > > > > >> > > > > > >> > > > > Jun > >> > > > > > >> > > > > On Mon, Jan 22, 2018 at 4:35 PM, Jason Gustafson > >> > > > > <ja...@confluent.io>> > wrote: > >> > > > > > >> > > > > > > > >> > > > > > > What if we want to have fetch sessions for non-incremental > >> > > > > > > fetches> > in the > >> > > > > > > future, though? Also, we don't expect this configuration to > >> > > > > > > be> > changed > >> > > > > > > often, so it doesn't really need to be short. > >> > > > > > > >> > > > > > > >> > > > > > Hmm.. But in that case, I'm not sure we'd need to distinguish > >> > > > > > the two> > > > cases. If the non-incremental sessions are > >> > occupying space > >> > > > proportional to > >> > > > > > the fetched partitions, using the same config for both would be> > >> > > >> > reasonable. > >> > > > > > If they are not (which is more likely), we probably wouldn't > >> > > > > > need a> > config > >> > > > > > at all. Given that, I'd probably still opt for the more concise > >> > > > > > name.> > It's > >> > > > > > not a blocker for me though. > >> > > > > > > >> > > > > > +1 on the KIP. > >> > > > > > > >> > > > > > -Jason > >> > > > > > > >> > > > > > On Mon, Jan 22, 2018 at 3:56 PM, Colin McCabe > >> > > > > > <cmcc...@apache.org>> > wrote: > >> > > > > > > >> > > > > > > On Mon, Jan 22, 2018, at 15:42, Jason Gustafson wrote: > >> > > > > > > > Hi Colin, > >> > > > > > > > > >> > > > > > > > This is looking good to me. A few comments: > >> > > > > > > > > >> > > > > > > > 1. The fetch type seems unnecessary in the request and > >> > > > > > > > response> > schemas > >> > > > > > > > since it can be inferred by the sessionId/epoch. > >> > > > > > > > >> > > > > > > Hi Jason, > >> > > > > > > > >> > > > > > > Fair enough... if we need it later, we can always bump the RPC> > >> > > version. > >> > > > > > > > >> > > > > > > > 2. I agree with Jun that a separate array for partitions to > >> > > > > > > > remove> > > > would > >> > > > > > > be > >> > > > > > > > more intuitive. > >> > > > > > > > >> > > > > > > OK. I'll switch it to using a separate array. > >> > > > > > > > >> > > > > > > > 3. I'm not super thrilled with the cache configuration since > >> > > > > > > > it> > seems > >> > > > > > to > >> > > > > > > > tie us a bit too closely to the implementation. You've > >> > > > > > > > mostly> > convinced > >> > > > > > > me > >> > > > > > > > on the need for the slots config, but I wonder if we can at > >> > > > > > > > least> > do > >> > > > > > > > without "min.incremental.fetch.session.eviction.ms"? For > >> > > > > > > > one, I> > think > >> > > > > > > the > >> > > > > > > > broker should reserve the right to evict sessions at will. > >> > > > > > > > We> > shouldn't > >> > > > > > > be > >> > > > > > > > stuck maintaining a small session at the expense of a much > >> > > > > > > > larger> > one > >> > > > > > > just > >> > > > > > > > to enforce this timeout. Internally, I think having some > >> > > > > > > > cache> > > > stickiness > >> > > > > > > > to avoid thrashing makes sense, but I think static values > >> > > > > > > > are> > likely to > >> > > > > > > be > >> > > > > > > > good enough and that lets us retain some flexibility to > >> > > > > > > > change the> > > > > behavior > >> > > > > > > > in the future. > >> > > > > > > > >> > > > > > > OK. > >> > > > > > > > >> > > > > > > > 4. I think the word "incremental" is redundant in the config > >> > > > > > > > names.> > > > Maybe > >> > > > > > > > it could just be "max.fetch.session.cache.slots" for > >> > > > > > > > example?> > > > > > >> > > > > > > What if we want to have fetch sessions for non-incremental > >> > > > > > > fetches> > in the > >> > > > > > > future, though? Also, we don't expect this configuration to > >> > > > > > > be> > changed > >> > > > > > > often, so it doesn't really need to be short. > >> > > > > > > > >> > > > > > > best, > >> > > > > > > Colin > >> > > > > > > > >> > > > > > > > > >> > > > > > > > Thanks, > >> > > > > > > > Jason > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > On Sat, Jan 20, 2018 at 12:54 PM, Colin McCabe > >> > > > > > > > <cmcc...@apache.org> > > > >> > > > > > > wrote: > >> > > > > > > > > >> > > > > > > > > On Fri, Jan 19, 2018, at 15:02, Jun Rao wrote: > >> > > > > > > > > > Hi, Colin, > >> > > > > > > > > > > >> > > > > > > > > > Thanks for the KIP. Looks good to me overall. Just a > >> > > > > > > > > > couple of> > more > >> > > > > > > > > > comments. > >> > > > > > > > > > > >> > > > > > > > > > 1. As I mentioned earlier, it might be useful to add > >> > > > > > > > > > some> > metrics > >> > > > > > for > >> > > > > > > > > > monitoring the usage of the session cache. For example, > >> > > > > > > > > > it> > would be > >> > > > > > > > > useful > >> > > > > > > > > > to know how many slots are being used (or unused), # of > >> > > > > > > > > > total> > > > > partitions > >> > > > > > > > > in > >> > > > > > > > > > the cached slots (to understand space), the eviction > >> > > > > > > > > > rate (to> > see > >> > > > > > if > >> > > > > > > > > there > >> > > > > > > > > > is any churn), etc. > >> > > > > > > > > > >> > > > > > > > > Thanks, Jun. Sorry-- I meant to address this earlier, but > >> > > > > > > > > I> > forgot > >> > > > > > > about > >> > > > > > > > > it. I just added some proposed metrics to the KIP wiki. > >> > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > 2. Using max_bytes to 0 represent the removal of a > >> > > > > > > > > > partition> > seems > >> > > > > > > > > > unintuitive. Perhaps it's better to either add a flag > >> > > > > > > > > > per> > partition > >> > > > > > > or > >> > > > > > > > > add > >> > > > > > > > > > a removed partition list. > >> > > > > > > > > > >> > > > > > > > > Perhaps if we use max_bytes -1 to represent removal, it > >> > > > > > > > > will be> > more > >> > > > > > > > > intuitive? After all, -1 bytes is clearly not a valid > >> > > > > > > > > amount of> > > > bytes > >> > > > > > > to > >> > > > > > > > > fetch. Or should be have a separate array of removed > >> > > > > > TopicPartitions? > >> > > > > > > > > > >> > > > > > > > > On a related note, in the FetchResponse#PartitionData, we > >> > > > > > > > > have an> > > > > "error" > >> > > > > > > > > field, plus highWatermark, lastStableOffset, > >> > > > > > > > > logStartOffset, etc.> > > > But > >> > > > > > > when > >> > > > > > > > > the "error" field is set, those other fields are not used.> > >> > > Perhaps > >> > > > > > we > >> > > > > > > > > could save some space by just having a separate array of > >> > > > "partitions > >> > > > > > > with > >> > > > > > > > > errors." In the common case where there are no errors, > >> > > > > > > > > this> > would > >> > > > > > > save 2 > >> > > > > > > > > bytes per partition, which could be quite significant in > >> > > > > > > > > large> > > > > responses. > >> > > > > > > > > > >> > > > > > > > > best, > >> > > > > > > > > Colin > >> > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > Jun > >> > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > On Thu, Jan 18, 2018 at 6:15 PM, Colin McCabe < > >> > > > cmcc...@apache.org> > >> > > > > > > > > wrote: > >> > > > > > > > > > > >> > > > > > > > > > > Hi all, > >> > > > > > > > > > > > >> > > > > > > > > > > I updated the KIP. There is also an implementation of > >> > > > > > > > > > > this> > KIP > >> > > > > > > here: > >> > > > > > > > > > > https://github.com/apache/kafka/pull/4418 > >> > > > > > > > > > > > >> > > > > > > > > > > The updated implementation simplifies a few things, > >> > > > > > > > > > > and adds> > the > >> > > > > > > > > ability > >> > > > > > > > > > > to incrementally add or remove individual partitions > >> > > > > > > > > > > in an> > > > > incremental > >> > > > > > > > > > > fetch request. > >> > > > > > > > > > > > >> > > > > > > > > > > best, > >> > > > > > > > > > > Colin > >> > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > On Tue, Dec 19, 2017, at 19:28, Colin McCabe wrote: > >> > > > > > > > > > > > Hi all, > >> > > > > > > > > > > > > >> > > > > > > > > > > > I'd like to start the vote on KIP-227: Incremental > >> > > > > > > > > > > > Fetch> > > > > Requests. > >> > > > > > > > > > > > > >> > > > > > > > > > > > The KIP is here: > >> > > > > > > > > > > > https://cwiki.apache.org/ > >> confluence/display/KAFKA/KIP-> > >> > > > > > > > > > 227%3A+Introduce+Incremental+FetchRequests+to+Increas- > >> > > > > > > > > > > e+> > > > > > > > > Partition+Scalability > >> > > > > > > > > > > > > >> > > > > > > > > > > > and discussion thread earlier: > >> > > > > > > > > > > > https://www.mail-archive.com/ > >> > dev@kafka.apache.org/msg83115> > . > >> > > > > > html > >> > > > > > > > > > > > > >> > > > > > > > > > > > thanks, > >> > > > > > > > > > > > Colin > >> > > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > >> > > >> > > >>
