No qualms with that here; it'll be a bit before GA so this has time to soak.
On Thu, Aug 27, 2020 at 8:21 PM Blake Eggleston <beggles...@apple.com.invalid> wrote: > Caleb is currently working through his second round of review, and Marcus > said he's about halfway through his review as of this morning. So I'd > expect it to be committed within a week or so. > > > On Aug 27, 2020, at 5:09 PM, Joshua McKenzie <jmcken...@apache.org> > wrote: > > > > Is there an ETA on them landing? The later, the more risk to stability of > > GA due to lack of time soaking. > > > > On Thu, Aug 27, 2020 at 4:01 PM Blake Eggleston > > <beggles...@apple.com.invalid> wrote: > > > >> Hi dev@, > >> > >> Mick asked that I check in w/ the dev list about CASSANDRA-15393. > There's > >> some concern regarding the patch and it's suitability for inclusion in > >> 4.0-beta. > >> > >> CASSANDRA-15393 reduces garbage created by compaction and the read paths > >> by about 25%. It's part of CASSANDRA-15387, which, including this patch, > >> reduces garbage from the read and compaction paths by about 50%. > >> CASSANDRA-15393 does this by supporting byte array backed cell and > >> clustering types, which is acheived by abstracting the backing type > >> (ByteBuffer/byte[]) from the serialization logic. > >> > >> To avoid paying the allocation cost of adding a container object, > >> singleton "accessor" objects are used to operate on the actual data. See > >> here for an example: > >> https://gist.github.com/bdeggleston/52910225b817a8d54353125ca03f521d > >> > >> Mick and Robert Stupp have raised a few concerns, summarized below: > >> > >> 1. The patch is large (208 files / ~3.5k LOC) > >> 2. Concerns about impact on stability > >> 3. Parameterizing cell/clustering value types in this way makes > >> ClassCastExceptions possible. > >> 4. implications of feature freeze > >> > >> The patch is large, but the vast majority of it is adding type > parameters > >> to things. The changes here are wide, but not deep. The most complex > parts > >> are the collection serializers and other places where we're now having > to > >> do offset bookkeeping. These should be carefully reviewed, but they > >> shouldn't be too difficult to verify and I've added some randomized > tests > >> to check them against a wide range of schemas. I'll also run some diff > >> tests against clusters internally. > >> > >> Parameterizing cell and clustering values does make ClassCastExceptions > >> possible, but java's type system guards against this for the most part. > >> Regarding the feature freeze, I don't think it applies to performance > >> improvements. > >> > >> Back to the point about stability though: in pracice, compaction gc is a > >> major contributor to cluster instability. In my experience, about 30% of > >> availability issues are gc related. Also, compaction gc tends to be the > >> limiting factor for repair, host replacements, and other topology > changes, > >> which limits how quickly you can recover from other issues. So the patch > >> does add some risk, but I think it's a net win for stability. > >> > >> Thoughts? > >> --------------------------------------------------------------------- > >> To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org > >> For additional commands, e-mail: dev-h...@cassandra.apache.org > >> > >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org > For additional commands, e-mail: dev-h...@cassandra.apache.org > >
