Sure, Caleb. I will include the work as part of CASSANDRA-19534 <https://issues.apache.org/jira/browse/CASSANDRA-19534> in the CEP-41.
Jaydeep On Fri, May 3, 2024 at 7:48 AM Caleb Rackliffe <calebrackli...@gmail.com> wrote: > FYI, there is some ongoing sort-of-related work going on in > CASSANDRA-19534 <https://issues.apache.org/jira/browse/CASSANDRA-19534> > > On Wed, Apr 10, 2024 at 6:35 PM Jaydeep Chovatia < > chovatia.jayd...@gmail.com> wrote: > >> Just created an official CEP-41 >> <https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-41+%28DRAFT%29+Apache+Cassandra+Unified+Rate+Limiter> >> incorporating the feedback from this discussion. Feel free to let me know >> if I may have missed some important feedback in this thread that is not >> captured in the CEP-41. >> >> Jaydeep >> >> On Thu, Feb 22, 2024 at 11:36 AM Jaydeep Chovatia < >> chovatia.jayd...@gmail.com> wrote: >> >>> Thanks, Josh. I will file an official CEP with all the details in a few >>> days and update this thread with that CEP number. >>> Thanks a lot everyone for providing valuable insights! >>> >>> Jaydeep >>> >>> On Thu, Feb 22, 2024 at 9:24 AM Josh McKenzie <jmcken...@apache.org> >>> wrote: >>> >>>> Do folks think we should file an official CEP and take it there? >>>> >>>> +1 here. >>>> >>>> Synthesizing your gdoc, Caleb's work, and the feedback from this thread >>>> into a draft seems like a solid next step. >>>> >>>> On Wed, Feb 7, 2024, at 12:31 PM, Jaydeep Chovatia wrote: >>>> >>>> I see a lot of great ideas being discussed or proposed in the past to >>>> cover the most common rate limiter candidate use cases. Do folks think we >>>> should file an official CEP and take it there? >>>> >>>> Jaydeep >>>> >>>> On Fri, Feb 2, 2024 at 8:30 AM Caleb Rackliffe < >>>> calebrackli...@gmail.com> wrote: >>>> >>>> I just remembered the other day that I had done a quick writeup on the >>>> state of compaction stress-related throttling in the project: >>>> >>>> >>>> https://docs.google.com/document/d/1dfTEcKVidRKC1EWu3SO1kE1iVLMdaJ9uY1WMpS3P_hs/edit?usp=sharing >>>> >>>> I'm sure most of it is old news to the people on this thread, but I >>>> figured I'd post it just in case :) >>>> >>>> On Tue, Jan 30, 2024 at 11:58 AM Josh McKenzie <jmcken...@apache.org> >>>> wrote: >>>> >>>> >>>> 2.) We should make sure the links between the "known" root causes of >>>> cascading failures and the mechanisms we introduce to avoid them remain >>>> very strong. >>>> >>>> Seems to me that our historical strategy was to address individual >>>> known cases one-by-one rather than looking for a more holistic >>>> load-balancing and load-shedding solution. While the engineer in me likes >>>> the elegance of a broad, more-inclusive *actual SEDA-like* approach, >>>> the pragmatist in me wonders how far we think we are today from a stable >>>> set-point. >>>> >>>> i.e. are we facing a handful of cases where nodes can still get pushed >>>> over and then cascade that we can surgically address, or are we facing a >>>> broader lack of back-pressure that rears its head in different domains >>>> (client -> coordinator, coordinator -> replica, internode with other >>>> operations, etc) at surprising times and should be considered more >>>> holistically? >>>> >>>> On Tue, Jan 30, 2024, at 12:31 AM, Caleb Rackliffe wrote: >>>> >>>> I almost forgot CASSANDRA-15817, which introduced >>>> reject_repair_compaction_threshold, which provides a mechanism to stop >>>> repairs while compaction is underwater. >>>> >>>> On Jan 26, 2024, at 6:22 PM, Caleb Rackliffe <calebrackli...@gmail.com> >>>> wrote: >>>> >>>> >>>> Hey all, >>>> >>>> I'm a bit late to the discussion. I see that we've already discussed >>>> CASSANDRA-15013 <https://issues.apache.org/jira/browse/CASSANDRA-15013> >>>> and CASSANDRA-16663 >>>> <https://issues.apache.org/jira/browse/CASSANDRA-16663> at least in >>>> passing. Having written the latter, I'd be the first to admit it's a crude >>>> tool, although it's been useful here and there, and provides a couple >>>> primitives that may be useful for future work. As Scott mentions, while it >>>> is configurable at runtime, it is not adaptive, although we did >>>> make configuration easier in CASSANDRA-17423 >>>> <https://issues.apache.org/jira/browse/CASSANDRA-17423>. It also is >>>> global to the node, although we've lightly discussed some ideas around >>>> making it more granular. (For example, keyspace-based limiting, or limiting >>>> "domains" tagged by the client in requests, could be interesting.) It also >>>> does not deal with inter-node traffic, of course. >>>> >>>> Something we've not yet mentioned (that does address internode traffic) >>>> is CASSANDRA-17324 >>>> <https://issues.apache.org/jira/browse/CASSANDRA-17324>, which I >>>> proposed shortly after working on the native request limiter (and have just >>>> not had much time to return to). The basic idea is this: >>>> >>>> When a node is struggling under the weight of a compaction backlog and >>>> becomes a cause of increased read latency for clients, we have two safety >>>> valves: >>>> >>>> >>>> 1.) Disabling the native protocol server, which stops the node from >>>> coordinating reads and writes. >>>> 2.) Jacking up the severity on the node, which tells the dynamic snitch >>>> to avoid the node for reads from other coordinators. >>>> >>>> >>>> These are useful, but we don’t appear to have any mechanism that would >>>> allow us to temporarily reject internode hint, batch, and mutation messages >>>> that could further delay resolution of the compaction backlog. >>>> >>>> >>>> Whether it's done as part of a larger framework or on its own, it still >>>> feels like a good idea. >>>> >>>> Thinking in terms of opportunity costs here (i.e. where we spend our >>>> finite engineering time to holistically improve the experience of operating >>>> this database) is healthy, but we probably haven't reached the point of >>>> diminishing returns on nodes being able to protect themselves from clients >>>> and from other nodes. I would just keep in mind two things: >>>> >>>> 1.) The effectiveness of rate-limiting in the system (which includes >>>> the database and all clients) as a whole necessarily decreases as we move >>>> from the application to the lowest-level database internals. Limiting >>>> correctly at the client will save more resources than limiting at the >>>> native protocol server, and limiting correctly at the native protocol >>>> server will save more resources than limiting after we've dispatched >>>> requests to some thread pool for processing. >>>> 2.) We should make sure the links between the "known" root causes of >>>> cascading failures and the mechanisms we introduce to avoid them remain >>>> very strong. >>>> >>>> In any case, I'd be happy to help out in any way I can as this moves >>>> forward (especially as it relates to our past/current attempts to address >>>> this problem space). >>>> >>>> >>>> >>>>
