Re: [DISCUSS] CASSANDRA-15234

[Ekaterina Dimitrova <e....@gmail.com>]

Hi everyone,

I have some good news and a bit of not that good but also not that bad.
CASSANDRA-15234 was committed last night, you will need to rebase CCM,
DTest and Trunk (if you use your own CCM and DTest branches). Push to
GitHub prior running CI should be in the order CCM -> DTest -> Trunk.
Unfortunately, we have new issues with CCM retagging (we solved different
ones but related before and things were working for some time
CASSANDRA-16688 <https://issues.apache.org/jira/browse/CASSANDRA-16688>)
and CircleCI. After retagging CCM it seems now CircleCI doesn't pick the
new tag and if you want to use CircleCI for testing, you will need to add
-e in requirements.txt:

-e git+https://github.com/riptano/ccm.git@cassandra-test#egg=ccm

The post-commit build in Jenkins looks fine, it picked up the new CCM tag.
I already have a ticket CASSANDRA-17351
<https://issues.apache.org/jira/browse/CASSANDRA-17351>. If anyone has any
ideas how to fix this permanently, all are welcome.

About CASSANDRA-15234, old and new yaml and format should both work.Further
to make it smoother for our users to migrate whenever they have time to the
new yaml, that gave us the chance also not to have to update the parameters
in the DTest suite but keep on exercising the old ones(one more way of
testing the backward compatibility too further to all new tests added). BUT
please, add any new tests using the new config so we can migrate in time.
You can find more details in the three primary classes Duration Spec,
DataStorageSpec and DataRateSpec (two of them are also extended, more
details in follow up tickets and posts) Backward compatibility is provided
through annotations used in Config.java. There is Converters enum to handle
different cases for backward compatibility.

Another rule is to start adding any new config with only the smallest
supported units.

I will explain and add full details in the docs I am already working on as
part of - CASSANDRA-17246
<https://issues.apache.org/jira/browse/CASSANDRA-17246> I am planning also
on two posts - one for the users and one for us how to use the new
framework/format and what to expect.

Enjoy the rest of your weekend and apologise for the CircleCI temporary
inconvenience.

Bests regards,
Ekaterina

On Mon, 25 Oct 2021 at 10:19, Ekaterina Dimitrova <e....@gmail.com>
wrote:

> Thank you Benedict.
>
> Considering there were no objections I am closing the discussion and
> getting back to work on the ticket itself. Thank you all. Have a great week
> ahead.
>
> On Wed, 20 Oct 2021 at 18:06, benedict@apache.org <be...@apache.org>
> wrote:
>
>> Thanks for moving this forwards Ekaterina.
>>
>> I think what we perhaps discovered is that there’s not really any
>> consensus about how to best do config files. I think in this situation it’s
>> best to defer to the one who’s actually putting in the time to _do_, so I
>> am more than happy to defer to your decisions.
>>
>> I’m sure everyone is looking forward to the improved consistency of this
>> work.
>>
>>
>> From: Ekaterina Dimitrova <e....@gmail.com>
>> Date: Wednesday, 20 October 2021 at 22:27
>> To: dev@cassandra.apache.org <de...@cassandra.apache.org>
>> Subject: Re: [DISCUSS] CASSANDRA-15234
>> Hi everyone,
>>
>> I think it is time to summarize the discussion.
>>
>> First of all, thank you for all the valuable input, suggestions, concerns,
>> and comments!
>>
>> The things that I believe we all agree on:
>>
>>    -
>>
>>    Simplicity for maintenance on our end - automation as much as possible
>>    so we don’t have to maintain more than one configuration file and our
>>    config is less prone to human errors while adding new features
>>    -
>>
>>    Simplicity for our users - as less confusing and as simple as possible
>>    and having in mind the users’ toolset
>>    -
>>
>>    Simplicity for testing and verification of the different config file
>>    formats
>>
>>
>> It seems to me that most people want to see committed both proposed
>> versions(feel free to correct me if I am wrong) with revision of the
>> default values and potentially commented out all parameters that are not
>> really mandatory to be changed. Also, versions with striped comments plus
>> a
>> way to maintain everything automatically, as much as possible.
>>
>> With that said it seems to me the current patch in CASSANDRA-15234 can be
>> committed after rebase and addressing any outstanding review comments. The
>> new version of cassandra.yaml, grouping the parameters can be added in a
>> new ticket by me or anyone with free cycles for that. It will require
>> additional work on the backward compatibility and the opportunity for
>> Cassandra to operate on all of the current versions but it will be new
>> additional opportunity which doesn’t disqualify the old ones so it seems
>> as
>> a fair game to be added at any point in time in the future as it won’t be
>> a
>> breaking change. We won’t replace anything. We will only add more options.
>>
>> If someone disagrees and wants to implement all possible options and
>> functionalities at once, I will be happy to handover the work and try to
>> find the time to provide feedback/reviews later.
>>
>> Please do not hesitate to correct me if I misunderstood something.
>>
>> I will leave this discussion open until Monday and if there are no
>> objections I will continue with CASSANDRA-15234 as per my proposal.
>>
>> Best regards,
>>
>> Ekaterina
>>
>> On Fri, 10 Sep 2021 at 20:18, Patrick McFadin <pm...@gmail.com> wrote:
>>
>> > Ah, I feel like cassandra.yaml discussions are such an evergreen topic.
>> >
>> > This was something brought up a while back, but I remember years ago we
>> > talked about emulating the config options that some other databases have
>> > done. Providing different versions of the config for different
>> approaches.
>> > For instance, MySQL has had 'my-small.cnf' with just the bare minimum
>> > config and restricted parameters for something like a laptop. A friendly
>> > option for newcomers would be a clearly labeled  'cassandra-small.yaml'
>> > with just the bare minimum and good comments. Then people new to
>> Cassandra
>> > wouldn't have a panic moment wondering if they have to know what
>> concurrent
>> > compactors are and how many you actually need? (Is there a right answer
>> > even???) It's tackling the way operators approach config by the use case
>> > they are trying to satisfy. Run one node on my laptop. Run a small
>> cluster
>> > on a budget cloud server. Run any size cluster on a ginormous server.
>> >
>> > Unfortunately, the cleaner solution would be how Apache HTTD solved it
>> back
>> > in the day with include files. It made config management much easier and
>> > the overwhelm factor much lower. Yaml doesn't support it and it would
>> all
>> > have to be custom code in the Cassandra config loader. Not the best
>> option
>> > really.
>> >
>> > Back to the original question, I think Ekaterina's sectioned version
>> could
>> > be used for new operators because there is a lot to learn looking at the
>> > comments.  Publish the following options:
>> >
>> > cassandra-small.yaml: Just the 'Quickstart' section
>> > cassandra-medium.yaml: 'Quickstart' and 'Commonly used' with sane
>> defaults
>> > cassandra-advanced.yaml: Every section
>> >
>> > The addition is a similarly named JVM properties file .
>> >
>> > As somebody who has been using Cassandra for a while and would like to
>> have
>> > a more verbose version (especially for config management) Benedict's
>> > grouped version is fantastic. Just one option there:
>> >
>> > cassandra-full.yaml
>> >
>> > That's my idea to satisfy the various operators that approach a new
>> > install.
>> >
>> > Patrick
>> >
>> > On Fri, Sep 10, 2021 at 3:31 PM Jeremiah D Jordan <
>> > jeremiah.jordan@gmail.com>
>> > wrote:
>> >
>> > > > Also, if you run the above command you will see we actually have a
>> lot
>> > > of things show (129 lines)… it would be nice to clean it up as only a
>> > small
>> > > subset is required and most shown normal users won’t care
>> > >
>> > > +1 for this.  It would be good to clean up the config code and yaml
>> such
>> > > that only “things that are required to be changed” are not commented
>> out
>> > in
>> > > the file, and everything else is commented out by default.  Last I
>> > checked
>> > > there were many fields that when commented out would not use a
>> sensible
>> > > value, or would result in NPE’s because they didn’t have a code level
>> > > default.
>> > >
>> > > -Jeremiah
>> > >
>> > > > On Sep 10, 2021, at 1:24 PM, David Capwell
>> <dcapwell@apple.com.INVALID
>> > >
>> > > wrote:
>> > > >
>> > > > We can have both, but I would hope we do not have humans maintaining
>> > > both.  If we maintain the commented one, and did something like the
>> below
>> > > while we compile then the burden to maintain doesn’t exist
>> > > >
>> > > > # remove comments and empty lines
>> > > > $ egrep -v '^[[:space:]]*#|^[[:space:]]*$' conf/cassandra.yaml.doc >
>> > > conf/cassandra.yaml
>> > > >
>> > > > We do this right now with conf/hotspot_compiler so as long as our
>> build
>> > > maintains the other file +1
>> > > >
>> > > > Also, if you run the above command you will see we actually have a
>> lot
>> > > of things show (129 lines)… it would be nice to clean it up as only a
>> > small
>> > > subset is required and most shown normal users won’t care
>> > > >
>> > > >> On Sep 3, 2021, at 6:45 AM, benedict@apache.org wrote:
>> > > >>
>> > > >>> I think as the comments were stripped only for the POC. I guess
>> many
>> > > of them will get back
>> > > >> in the actual doc version unfortunately.
>> > > >>
>> > > >> Well, I think the grouped format lends itself to much briefer
>> > comments,
>> > > with groups of related parameters getting an overall description. Even
>> > as a
>> > > developer who understands most of the toggles I found the old file
>> very
>> > > hard to navigate.
>> > > >>
>> > > >> I also don’t see why we cannot have both heavily commented versions
>> > and
>> > > uncommented (or lightly commented) versions.
>> > > >>
>> > > >> I don’t personally see why multiple different config templates
>> would
>> > be
>> > > confusing if they’re in a suitably labelled directory, even if we
>> settle
>> > on
>> > > one for the default. It might even be nice to have a pared-down config
>> > that
>> > > has only those properties we expect the normal user to need, so it’s
>> > > particularly easy to navigate.
>> > > >>
>> > > >>
>> > > >> From: Ekaterina Dimitrova <e....@gmail.com>
>> > > >> Date: Friday, 3 September 2021 at 14:40
>> > > >> To: dev@cassandra.apache.org <de...@cassandra.apache.org>
>> > > >> Subject: Re: [DISCUSS] CASSANDRA-15234
>> > > >>>>
>> > > >>>> It’s worth noting that the two don’t have to be in >conflict: we
>> > could
>> > > >>> offer two template yaml with the parameters grouped differently,
>> for
>> > > users
>> > > >>> to decide for themselves.
>> > > >>
>> > > >> Sure, my only concern is that three versions of the yaml could
>> bring
>> > > >> confusion (we will have backward compatibility to the current one
>> for
>> > > some
>> > > >> time). But it might be only me. I am open for feedback
>> > > >>
>> > > >>
>> > > >>> If we can document this, it would be great as stuff >like
>> “enabled”
>> > are
>> > > >>> inconsistent so not sure if I did it properly =D
>> > > >>>
>> > > >> Well, this is for now only in the ticket in the first version but
>> no
>> > one
>> > > >> raised any concern. We will definitely have to update our docs on
>> this
>> > > and
>> > > >> whatever else we came to agreement on - both for users and
>> > contributors.
>> > > >>
>> > > >>> though I will agree that it can be hard for some >tools (such
>> > > >>> as bash templating), but feel we can always find a >common ground
>> > > >> Valid point and I believe it is one of the reasons we delayed the
>> > > ticket,
>> > > >> in order to get feedback on that. I am really interested to hear
>> what
>> > > >> concerns people might have.
>> > > >>
>> > > >>
>> > > >>> Opening up a 1500+ line .yaml file is very daunting, >even if
>> most of
>> > > it is
>> > > >>> comments. Can't blame folks for being >overwhelmed at the
>> prospect of
>> > > >> tuning
>> > > >>> Cassandra w/that as our operator config API. :)
>> > > >> I am all in for simplification and to make our users’ lives easier.
>> > But
>> > > at
>> > > >> this point we shouldn’t be comparing the length of the files I
>> think
>> > as
>> > > the
>> > > >> comments were stripped only for the POC. I guess many of them will
>> get
>> > > back
>> > > >> in the actual doc version unfortunately.
>> > > >>
>> > > >> Thank you all,
>> > > >> Ekaterina
>> > > >>
>> > > >> On Thu, 2 Sep 2021 at 20:07, Joshua McKenzie <jmckenzie@apache.org
>> >
>> > > wrote:
>> > > >>
>> > > >>> Reading through the two, the grouping approach seems like it's a
>> lot
>> > > more
>> > > >>> friendly to newcomers as well as providing context specific cues
>> for
>> > > >>> relationships between params you're editing. Showing and not
>> telling,
>> > > if
>> > > >>> you will.
>> > > >>>
>> > > >>> Opening up a 1500+ line .yaml file is very daunting, even if most
>> of
>> > > it is
>> > > >>> comments. Can't blame folks for being overwhelmed at the prospect
>> of
>> > > tuning
>> > > >>> Cassandra w/that as our operator config API. :)
>> > > >>>
>> > > >>> ~Josh
>> > > >>>
>> > > >>> On Thu, Sep 2, 2021 at 1:48 PM David Capwell
>> > > <dc...@apple.com.invalid>
>> > > >>> wrote:
>> > > >>>
>> > > >>>> Thanks for bringing this back up; Caleb and I were talking about
>> the
>> > > lack
>> > > >>>> of clarity with regard to CASSANDRA-16896, fleshing this out
>> would
>> > > make
>> > > >>>> those configs nicer!
>> > > >>>>
>> > > >>>>> To standardize naming - that we did by agreeing to the form
>> > noun_verb
>> > > >>>>
>> > > >>>> If we can document this, it would be great as stuff like
>> “enabled”
>> > are
>> > > >>>> inconsistent so not sure if I did it properly =D
>> > > >>>>
>> > > >>>>>
>> > > >>>>> Provision of values with units while maintaining backward
>> > > >>>> compatibility.
>> > > >>>>
>> > > >>>> +1000000000000
>> > > >>>>
>> > > >>>> I really hate local_read_size_threshold_kb; I would love
>> > > >>>> local_read_size_threshold: 10kb.  Once we have the
>> infrastructure in
>> > > >>> place
>> > > >>>> (believe your patch before had these tools) I would love to
>> switch!
>> > > >>>>
>> > > >>>>
>> > > >>>>> Another proposal is done by Benedict; grouping the config
>> > parameters.
>> > > >>>>
>> > > >>>> Yep, this is what triggered Caleb and I to talk about this
>> thread!
>> > To
>> > > >>>> group or not to group; that is the question
>> > > >>>>
>> > > >>>> Personally I like grouping from an organization point of view so
>> am
>> > in
>> > > >>>> favor of that; though I will agree that it can be hard for some
>> > tools
>> > > >>> (such
>> > > >>>> as bash templating), but feel we can always find a common ground
>> > > >>>>
>> > > >>>>
>> > > >>>>> On Sep 2, 2021, at 8:44 AM, benedict@apache.org wrote:
>> > > >>>>>
>> > > >>>>> Thanks for bringing this to the list Ekaterina!
>> > > >>>>>
>> > > >>>>> It’s worth noting that the two don’t have to be in conflict: we
>> > could
>> > > >>>> offer two template yaml with the parameters grouped differently,
>> for
>> > > >>> users
>> > > >>>> to decide for themselves.
>> > > >>>>>
>> > > >>>>> The proposals primarily define parameter names differently,
>> with my
>> > > >>>> proposal going by kind->place, and the other proposal maintaining
>> > > >>> (mostly)
>> > > >>>> the existing name form (which is a bit more like place->kind).
>> While
>> > > the
>> > > >>>> example yaml groups by kind, you can convert nested definitions
>> > into a
>> > > >>>> ‘dot’ form (e.g. limits.concurrency.reads) for use in a different
>> > > >>> grouping.
>> > > >>>>>
>> > > >>>>> One advantage of grouping parameters together is that it aids
>> > > >>>> maintaining coherency of naming between systems, and also
>> > potentially
>> > > >>>> permits a more succinct config file and better discovery. But
>> it’s
>> > far
>> > > >>> from
>> > > >>>> a silver bullet, as value judgements have to be made about where
>> the
>> > > >>>> grouping lines are. I’m sure anything we settle on will be a huge
>> > > >>>> improvement over the status quo, however.
>> > > >>>>>
>> > > >>>>>
>> > > >>>>>
>> > > >>>>>
>> > > >>>>> From: Ekaterina Dimitrova <e....@gmail.com>
>> > > >>>>> Date: Thursday, 2 September 2021 at 16:32
>> > > >>>>> To: dev@cassandra.apache.org <de...@cassandra.apache.org>
>> > > >>>>> Subject: [DISCUSS] CASSANDRA-15234
>> > > >>>>> Hi team,
>> > > >>>>>
>> > > >>>>> I would like to bring to the attention of the community
>> > > >>> CASSANDRA-15234,
>> > > >>>>> standardise config and JVM parameters.
>> > > >>>>>
>> > > >>>>> This is work we discussed back in Summer 2020 just before our
>> first
>> > > 4.0
>> > > >>>>> Beta release. During the discussion we figured out that there is
>> > more
>> > > >>>> than
>> > > >>>>> one option to do the job and not enough time to get user
>> feedback
>> > and
>> > > >>>>> finish it so this was delayed post-4.0 And here I am, bringing
>> it
>> > > back
>> > > >>> to
>> > > >>>>> the table.
>> > > >>>>>
>> > > >>>>> This work’s goal is:
>> > > >>>>>
>> > > >>>>> -
>> > > >>>>>
>> > > >>>>> To standardize naming - that we did by agreeing to the form
>> > noun_verb
>> > > >>>>> -
>> > > >>>>>
>> > > >>>>> Provision of values with units while maintaining backward
>> > > >>>> compatibility.
>> > > >>>>>
>> > > >>>>>
>> > > >>>>> Those two parts are more or less already done.
>> > > >>>>>
>> > > >>>>> More interesting is the third part - reorganizing the
>> > cassandra.yaml
>> > > >>>> file.
>> > > >>>>>
>> > > >>>>> My personal approach was to split it into sections, done here
>> > > >>>>> <
>> > > >>>>
>> > > >>>
>> > >
>> >
>> https://github.com/ekaterinadimitrova2/cassandra/blob/b4eebe080835da79d032f9314262c268b71172a8/conf/cassandra.yaml
>> > > >>>>>
>> > > >>>>> .
>> > > >>>>>
>> > > >>>>> Another proposal is done by Benedict; grouping the config
>> > parameters.
>> > > >>>>>
>> > > >>>>> To make it clearer, he created a yaml
>> > > >>>>> <
>> > > >>>>
>> > > >>>
>> > >
>> >
>> https://github.com/belliottsmith/cassandra/blob/5f80d1c0d38873b7a27dc137656d8b81f8e6bbd7/conf/cassandra_nocomment.yaml
>> > > >>>>>
>> > > >>>>> with comments mostly stripped.
>> > > >>>>>
>> > > >>>>> In his version, there are basic settings for network, disk etc
>> all
>> > > >>>> grouped
>> > > >>>>> together, followed by operator tuneables mostly under limits
>> within
>> > > >>> which
>> > > >>>>> we now have throughput, concurrency, capacity. This leads to
>> > settings
>> > > >>> for
>> > > >>>>> some features being kept separate (most notably for caching),
>> but
>> > > helps
>> > > >>>> the
>> > > >>>>> operator understand what they have to play with for controlling
>> > > >>> resource
>> > > >>>>> consumption.
>> > > >>>>>
>> > > >>>>> I am interested to hear what people think about the two options
>> or
>> > if
>> > > >>>>> anyone has another idea to share, open discussion.
>> > > >>>>>
>> > > >>>>> Thank you,
>> > > >>>>>
>> > > >>>>> Ekaterina
>> > > >>>>
>> > > >>>>
>> > > >>>>
>> > ---------------------------------------------------------------------
>> > > >>>> To unsubscribe, e-mail: dev-unsubscribe@cassandra.apache.org
>> > > >>>> For additional commands, e-mail: dev-help@cassandra.apache.org
>> > > >>>>
>> > > >>>>
>> > > >>>
>> > > >
>> > > >
>> > > >
>> ---------------------------------------------------------------------
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>> > > > For additional commands, e-mail: dev-help@cassandra.apache.org
>> > > >
>> > >
>> > >
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>> > >
>> > >
>> >
>>
>