Colin, I will keep the title for now, since all the previous discussions and links are tied to this title.
I can change the title at the end or add a clarification note in the doc. Xiongqi (Wesley) Wu On Tue, Sep 4, 2018 at 5:47 PM xiongqi wu <xiongq...@gmail.com> wrote: > Colin, > Thank you for comments. > see my inline reply below. > > Xiongqi (Wesley) Wu > > > On Tue, Sep 4, 2018 at 5:24 PM Colin McCabe <cmcc...@apache.org> wrote: > >> Hi Xiongqi, >> >> Thanks for this KIP. >> >> The name seems a bit ambiguous. Our compaction policies are already >> time-based, after all. It seems like this change is focused around adding >> a “max.compaction.lag.ms." Perhaps the KIP title should be something >> like "add maximum compaction lag time"? >> >> ==========> sure. I will change the title. > > > The active segment is forced to roll when either "max.compaction.lag.ms" >> > or "segment.ms" (log.roll.ms and log.roll.hours) has reached. >> >> If the max.compaction.lag.ms is low, it seems like segments will be >> rolled very frequently. This can be a source of problems in the cluster, >> since creating many different small log segments consumes a huge amount of >> cluster resources. Therefore, I would suggest adding a broker-level >> configuration which allows us to set a minimum value for >> max.compaction.lag.ms. If we let users set it on a per-topic basis, >> someone could set a value of 1 ms or something, and cause chaos. >> >> =========> this applies to segment.ms as well. Today users can set " > segment.ms" to a very low value, and cause a frequent rolling of active > segments. In my option, the minimum of "max.compaction.lag.ms" should be > based on the minimum of "segment.ms". Since today the minimum of > segment.ms is 1, "max.compaction.lag.ms" also starts with 1. "0" means > disable. I can use -1 as disable, but it is hard to define the meaning of > 0 because we cannot just roll the active segment immediately. > > > -- Note that an alternative configuration is to use -1 as "disabled" >> and 0 >> > as "immediate compaction". Because compaction lag is still determined >> > based on min.compaction.lag and how long to roll an active segment, >> the >> > actual lag for compaction is undetermined if we use "0". On the other >> > hand, we can already set "min.cleanable.dirty.ratio" to achieve the >> same >> > goal. So here we choose "0" as "disabled". >> >> I would prefer -1 to be the invalid setting. Treating 0 differently than >> 1 seems strange to me. >> >> =====> see my previous comment, I am not strongly against, but 0 is not > a valid configuration in my option. So I use "0" as disabled state. > > best, >> Colin >> >> >> On Tue, Sep 4, 2018, at 15:04, xiongqi wu wrote: >> > Let's VOTE for this KIP. >> > KIP: >> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-354 >> > %3A+Time-based+log+compaction+policy >> > >> > Implementation: >> > >> > https://github.com/apache/kafka/pull/5611 >> > >> > >> > >> > Xiongqi (Wesley) Wu >> >
