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
