I would love to have my questions answered and see some graphs I don’t think those are unreasonable asks nor do they take away from the awesome work done. I was suggesting 1-2 weeks for folks to have the opportunity to produce that data if the original authors didn’t have time. I also don’t think that’s unreasonable. but to be clear I’m not blocking anything. If folks want to merge I am not objecting.
I do think we should hold features to a high standard and personally “time worked on a feature” is not a criteria for me when considering why we should merge. It is absolutely worth recognizing and celebrating the massive invest and effort made here. It’s just an orthogonal point to me. As a contrived example: If 15452 was not as impactful performance wise after a year of on and off work I would’ve happily continue to address it or take a different approach. SASI took a year and a half or more and I still regret that we merged it into 3.x in the form we did using the same early contribution model. That was an example of an extreme, and out of our control case, of an entire team disbanding right after merge. Jordan On Fri, Mar 7, 2025 at 06:28 Jon Haddad <j...@rustyrazorblade.com> wrote: > I defer to the judgement of the folks that are most impacted by it - ones > that are in the code, working on the next release. If you all think it's > good to merge, then I am 100% in support of it. I suspect merging will > help get it out faster, and I don't see any future in which we don't ship > this in the next release. > > I will be happy to help answer the "how does it compare to paxos v2" > question post-merge. > > Jon > > > > On Fri, Mar 7, 2025 at 5:52 AM Josh McKenzie <jmcken...@apache.org> wrote: > >> 3.5 years is an incredible amount of time and work; it really is >> significant and thanks to everyone involved for the investment of time and >> energy. >> >> We have a rocky history with large, disruptive contributions in the past >> that have either blocked forward progress post-merge (CASSANDRA-8099), or >> lingered in the code-base increasing maintenance burden on other >> contributors for minimal or no user benefit (early open post SSD >> transition, witness replicas, materialized views). I'm sympathetic to where >> Jordan's questions stem from, as our history of leaving things in the >> codebase long after they've become vestigial or abandoned has slowed down >> our collective momentum maintaining the project on actively used features. >> >> That said, I don't think Accord will run afoul of some of those same >> patterns. Aside from the degree of investment already in it and sheer >> number of pmc members and committers involved, I believe it's a feature >> that's universally impactful and that if we had a metaphorical bus-factor >> change (entire group of people working on it disappeared the day after >> merge or decided to go on vacation for 5 years), others in the community >> would be willing to pick things up and keep it moving given its proximity >> to release readiness. >> >> The 2 questions Jordan asked resonate with me: 1) do we have line of >> sight to a fix on the schema issues, and I'll take the liberty of reframing >> 2) do we have line of sight to improvement on the performance front to be >> usable for multi-key transactions? (subtle: I don't think "parity with >> PaxosV2" is the right target, but rather "fast enough to be usable for >> multi-key transactions" since it's a new query paradigm). >> >> Given the context on contributor backing and if the answer is yes to >> those 2 questions (which I believe it is), I think we should generally be >> comfortable with merging the feature as experimental at this time. >> >> On Fri, Mar 7, 2025, at 12:54 AM, Benedict wrote: >> >> >> There are essentially three possible timelines to choose from here: >> >> 1) We agree in the next few days to merge to trunk. We will then >> prioritise rebasing onto trunk and resolving any pre-merge items starting >> next week. >> 2) There’s some more debate and agreement to merge to trunk in a week or >> two. In the meantime we will shift to internal-first development but we’ll >> likely prioritise the above work as soon as we can, which may be in a few >> weeks, so we can shift to trunk first development. >> 3) We don’t agree to merge accord anytime soon, so we shift to >> internal-first development for the time being. I’m not sure when we will >> prioritise any of the above. >> >> Our resources are finite and we’ve exhausted them (literally), so it’s >> pretty much pick one of the above. I don’t really mind which you pick, but >> I won’t personally be prioritising merge after this third attempt. >> >> >> On 6 Mar 2025, at 22:01, Jon Haddad <j...@rustyrazorblade.com> wrote: >> >> >> Hmm... I took a look at the cep-15-accord branch in GitHub, it looks like >> it's several hundred commits behind trunk. Since you'll need to rebase >> again before merge *anyways*, would it make sense to do it once more, and I >> can publish easy-cass-lab with the latest branch? If folks have concerns, >> it's easy to fire up a cluster (I do it constantly) and try it out. >> >> I think if we were to do this, out of consideration we should time box >> the amount of time for an evaluation and unless someone raises an >> objection, consider lazy consensus achieved. >> >> Jon >> >> >> >> On Thu, Mar 6, 2025 at 12:46 PM Benedict Elliott Smith < >> bened...@apache.org> wrote: >> >> Because we want to validate against the latest code in trunk, else we are >> validating stale behaviours. The cost of rebasing is high, so we do not do >> it frequently. That means we will likely stop developing OSS-first, as the >> focus will have to move to our internal branch that satisfies these >> criteria. >> >> Exactly what this might be for upstreaming I cannot say. Personally, I >> aim to work exclusively on the branch we are stabilising. If that is not >> trunk, the latency for my contributions being made public might be high, as >> I have a huge imbalance of over-investment to recoup, and anything >> unnecessary will be deferred. >> >> Since the feature is disabled, and the code is almost entirely isolated, >> I cannot imagine the cost to the community to removing this work would be >> very high. But, I do not intend to argue Accord’s case here. I will let you >> all decide. >> >> Please decide soon though, as it shapes our work planning. The positive >> reception so far had lead me to consider prioritising a move to trunk-first >> development within the next week or two, and the associated work that >> entails. However, if that was optimistic we will have to shift our plans. >> >> >> >> On 6 Mar 2025, at 20:16, Jordan West <jw...@apache.org> wrote: >> >> The work and effort in accord has been amazing. And I’m sure it sets a >> new standard for code quality and correctness testing which I’m also >> entirely behind. I also trust the folks working on it want to take it to >> the a fully production ready solution. But I’m worried about circumstances >> out of our control leaving us with a very complex feature that isn’t >> complete. >> >> I do have some questions. Could folks help me better understand why >> testing real workloads necessitates a merge (my understanding from the >> original reason is this is the impetus for why we would merge now)? Also I >> think the performance and scheme change caveats are rather large ones. One >> of accords promise was better performance and I think making schema changes >> with nodes down not being supported is a big gap. Could we have some >> criteria like “supports all the operations PaxosV2 supports” or “performs >> as well or better than PaxosV2 on [workload(s)]”? >> >> I understand waiting asks a lot of the authors in terms of baring the >> burden of a more complex merge. But I think we also need to consider what >> merging is asking the community to bear if the worst happens and we are >> unable to take the feature from its current state to something that can be >> widely used in production. >> >> Jordan >> >> >> On Wed, Mar 5, 2025 at 15:52 Blake Eggleston <bl...@ultrablake.com> >> wrote: >> >> >> +1 to merging it >> >> On Wed, Mar 5, 2025, at 12:22 PM, Patrick McFadin wrote: >> >> You have my +1 >> >> On Wed, Mar 5, 2025 at 12:16 PM Benedict <bened...@apache.org> wrote: >> > >> > Correct, these caveats should only apply to tables that have opted-in >> to accord. >> > >> > On 5 Mar 2025, at 20:08, Jeremiah Jordan <jerem...@apache.org> wrote: >> > >> > >> > So great to see all this hard work about to pay off! >> > >> > On the questions/concerns front, the only concern I would have towards >> merging this to trunk is if any of the caveats apply when someone is not >> using Accord. Assuming they only apply when the feature flag is enabled, I >> see no reason not to get this merged into trunk once everyone involved is >> happy with the state of it. >> > >> > -Jeremiah >> > >> > On Mar 5, 2025 at 12:15:23 PM, Benedict Elliott Smith < >> bened...@apache.org> wrote: >> >> >> >> That depends on all of you lovely people :D >> >> >> >> I think we should have finished merging everything we want before QA >> by ~Monday; certainly not much later. >> >> >> >> I think we have some upgrade and python dtest failures to address as >> well. >> >> >> >> So it could be pretty soon if the community is supportive. >> >> >> >> On 5 Mar 2025, at 17:22, Patrick McFadin <pmcfa...@gmail.com> wrote: >> >> >> >> >> >> What is the timing for starting the merge process? I'm asking because >> >> >> >> I have (yet another) presentation and this would be a cool update. >> >> >> >> >> >> On Wed, Mar 5, 2025 at 1:22 AM Benedict Elliott Smith >> >> >> >> <bened...@apache.org> wrote: >> >> >> >> > >> >> >> >> > Thanks everyone. >> >> >> >> > >> >> >> >> > Jon - your help will be greatly appreciated. We’ll let you know when >> we’ve got the cycles to invest in performance work (hopefully fairly soon). >> I expect the first step will be improving visibility so we can better >> understand what the system is doing (particularly the caching layers), but >> we can dig in together when ready. >> >> >> >> > >> >> >> >> > On 4 Mar 2025, at 18:15, Jon Haddad <j...@rustyrazorblade.com> wrote: >> >> >> >> > >> >> >> >> > Very exciting! >> >> >> >> > >> >> >> >> > I have a client that's very interested in Accord, so I should have >> budget to dig into it, especially on the performance side of things. >> >> >> >> > >> >> >> >> > Jon >> >> >> >> > >> >> >> >> > On Tue, Mar 4, 2025 at 9:57 AM Dmitry Konstantinov < >> netud...@gmail.com> wrote: >> >> >> >> >> >> >> >> >> >> Thank you to all Accord and TCM contributors, it is really exciting >> to see a development of such huge and wonderful features moving forward and >> opening the door to the new Cassandra epoch! >> >> >> >> >> >> >> >> >> >> On Tue, 4 Mar 2025 at 20:45, Blake Eggleston <bl...@ultrablake.com> >> wrote: >> >> >> >> >>> >> >> >> >> >>> Thanks Benedict! >> >> >> >> >>> >> >> >> >> >>> I’m really excited to see accord reach this milestone, even with >> these caveats. You seem to have left yourself off the list of contributors >> though, even though you’ve been a central figure in its development :) So >> thanks to all accord & tcm contributors, including Benedict, for making >> this possible! >> >> >> >> >>> >> >> >> >> >>> On Tue, Mar 4, 2025, at 8:00 AM, Benedict Elliott Smith wrote: >> >> >> >> >>> >> >> >> >> >>> Hi everyone, >> >> >> >> >>> >> >> >> >> >>> It’s been exactly 3.5 years since the first commit to >> cassandra-accord. Yes, really, it’s been that long. >> >> >> >> >>> >> >> >> >> >>> We will be starting to validate the feature against real workloads >> in the near future, so we can’t sensibly push off merging much longer. The >> following is a brief run-down of the state of play. There are no known >> bugs, but there remain a number of caveats we will be incrementally >> addressing in the run-up to a full release: >> >> >> >> >>> >> >> >> >> >>> [1] Accord is likely to be SLOW until further optimisations are >> implemented >> >> >> >> >>> [2] Schema changes have a number of hard edges >> >> >> >> >>> [3] Validation is ongoing, so there are likely still a number of >> bugs to shake out >> >> >> >> >>> [4] Many operator visibility/tooling/documentation improvements >> are pending >> >> >> >> >>> >> >> >> >> >>> To expand a little: >> >> >> >> >>> >> >> >> >> >>> [1] As of the last experiment we conducted, accord’s throughput >> was poor - also leading to higher LAN latencies. We have done no WAN >> experiments to date, but the protocol guarantees should already achieve >> better round-trip performance, in particular under contention. Improving >> throughput will be the main focus of attention once we are satisfied the >> protocol is otherwise stable, but our focus remains validation for the >> moment. >> >> >> >> >>> [2] Schema changes have not yet been well integrated with TCM. >> Dropping a table for instance will currently cause problems if nodes are >> offline. >> >> >> >> >>> [3] We have a range of validations we are already performing >> against cassandra-accord directly, and against its integration with >> Cassandra in cep-15-accord. We have run hundreds of billions of simulated >> transactions, and are still discovering some minor fault every few billion >> simulated transactions or so. There remains a lot more simulated validation >> to explore, as well as with real clusters serving real workloads. >> >> >> >> >>> [4] There are already a range of virtual tables for exploring >> internal state in Accord, and reasonably good metric support. However, >> tracing is not yet supported, and our metric and virtual table integrations >> need some further development. >> >> >> >> >>> [5] There are also other edge cases to address such as ensuring we >> do not reuse HLCs after restart, supporting ByteOrderPartitioner, and live >> migration from/to Paxos is undergoing fine-tuning and validation; probably >> there are some other things I am forgetting. >> >> >> >> >>> >> >> >> >> >>> Altogether the feature is fairly mature, despite these caveats. >> This is the fruit of the labour of a long list of contributors, including >> Aleksey Yeschenko, Alex Petrov, Ariel Weisberg, Blake Eggleston, Caleb >> Rackliffe and David Capwell, and represents a huge undertaking. It also >> wouldn’t have been possible without the work of Alex Petrov, Marcus >> Eriksson and Sam Tunnicliffe on delivering transactional cluster metadata. >> I hope you will join me in thanking them all for their contributions. >> >> >> >> >>> >> >> >> >> >>> Alex has also kindly produced some initial overview documentation >> for developers, that can be found here: >> https://github.com/apache/cassandra/blob/cep-15-accord/doc/modules/cassandra/pages/developing/accord/index.adoc. >> This will be expanded as time permits. >> >> >> >> >>> >> >> >> >> >>> Does anyone have any questions or concerns? >> >> >> >> >>> >> >> >> >> >>> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> >> >> Dmitry Konstantinov >> >> >> >> > >> >> >> >> > >> >> >> >> >> >> >> >>
