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From Hyukjin Kwon <>
Subject Re: Request to document the direct relationship between other configurations
Date Fri, 14 Feb 2020 04:42:53 GMT
It's okay to just follow one prevailing style. The main point I would like
to say is the fact that we should *document* the direct relationship of
For this case specifically, I don't think there is so much point here to
decide one hard requirement to follow for the mid-term. We have the final
goal to reach.

There are always many cases that requires committer's judgement. It is
impossible to put every single item to a guide line in practice.
So we usually trust their judgement in practice unless there's no explicit
objection. Here, my explicit objection is about no documentation for the
direct relationship
between configurations. Seems people think we should document this in
general as well.

In practice, I don't particularly mind what style is used in fact. I
vaguely guess the style isn't an issue to many other committers in general.
If this is the case, let's open a separate thread to discuss to confirm one
style - this wasn't the main issue I wanted to address in this thread.

Shall we conclude this thread by deciding to document the direct
relationship between configurations preferably in one prevailing style?

2020년 2월 14일 (금) 오전 11:36, Jungtaek Lim <>님이

> Even spark.dynamicAllocation.* doesn't follow 2-2, right? It follows the
> mix of 1 and 2-1, though 1 is even broken there.
> It doesn't matter If we just discuss about one-time decision - it may be
> OK to not to be strict on consistency, though it's not ideal. The thing is
> that these kind of "preferences" are making confusion on review phase:
> reviewers provide different comments and try to "educate" contributors on
> their preferences. Expectations for such cases heavily depends on who
> is/are reviewers of PR - there's no value on education.
> The codebase is the reference of implicit rules/policies which would apply
> to all contributors including newcomers. Let's just put our best efforts on
> being consistent on codebase. (We should have consensus to do this anyway.)
> On Thu, Feb 13, 2020 at 12:44 PM Hyukjin Kwon <> wrote:
>> I think it’s just fine as long as we’re consistent with the instances
>> having the description, for instance:
>>   When true and ‘spark.xx.xx’ is enabled, …
>> I think this is 2-2 in most cases so far. I think we can reference other
>> configuration keys in another configuration documentation by using
>> ADAPTIVE_EXECUTION_ENABLED.key as an example. So we don’t have
>> duplication problem in most cases.
>> Being consistent with the current base is a general guidance if I am not
>> mistaken. We have identified a problem and a good goal to reach.
>> If we want to change, let's do it as our final goal. Otherwise, let's
>> simplify it to reduce the overhead rather then having a policy for the
>> mid-term specifically.
>> 2020년 2월 13일 (목) 오후 12:24, Jungtaek Lim <>님이
>> 작성:
>>> I tend to agree that there should be a time to make thing be consistent
>>> (and I'm very happy to see the new thread on discussion) and we may want to
>>> take some practice in the interim.
>>> But for me it is not clear what is the practice in the interim. I
>>> pointed out the problems of existing style and if we all agree the problems
>>> are valid then we may need to fix it before start using it widely.
>>> For me the major question is "where" to put - at least there're two
>>> different approaches:
>>> 1) put it to the description of `.enable` and describe the range of
>>> impact (e.g.) put the description of "spark.A.enable" saying it will affect
>>> the following configurations under "spark.A".
>>> (I don't think it's good to enumerate all of affected configs, as
>>> `spark.dynamicAllocation.enable` is telling it is fragile.)
>>> 2) put it to the description of all affected configurations and describe
>>> which configuration is the prerequisite to let this be effective. e.g. put
>>> it on all configurations under `spark.dynamicAllocation` mentioning
>>> `spark.dynamicAllocation.enable` should be enabled to make this be
>>> effective.
>>> (I intended to skip mentioning "cross reference". Let's be pragmatic.)
>>> 2) has also two ways to describe:
>>> 2-1) Just mention simply - like "When dynamic allocation is enabled,",
>>> not pointing out the key to toggle. This hugely simplify the description,
>>> though end users may have to do the second guess to find the key to toggle.
>>> (It'll be intuitive when we structurize the configurations.)
>>> 2-2) Mention the key to toggle directly - like "This is effective only
>>> if spark.A.enable is set to true.". It's going to be longer depending on
>>> how long the configuration key is. Personally I'd feel verbose unless the
>>> key to toggle is not placed to the spot we can infer, but others may have
>>> different opinions.
>>> I may be missing some details, so please participate to add the details.
>>> Otherwise we may want to choose the best one, and have a sample form of
>>> description. (Once we reach here, it may be OK to add to the contribution
>>> doc, as that is the thing we agree about.)
>>> Without the details it's going to be a some sort of "preference" which
>>> is natural to have disagreement, hence it doesn't make sense someone is
>>> forced to do something if something turns out to be "preference".
>>> On Thu, Feb 13, 2020 at 11:10 AM Hyukjin Kwon <>
>>> wrote:
>>>> Adding those information is already a more prevailing style at this
>>>> moment, and this is usual to follow prevailing side if there isn't a
>>>> specific reason.
>>>> If there is confusion about this, I will explicitly add it into the
>>>> guide ( Let me know if
>>>> this still confuses or disagree.
>>>> 2020년 2월 13일 (목) 오전 9:47, Hyukjin Kwon <>님이
>>>>> Yes, that's probably our final goal to revisit the configurations to
>>>>> make it structured and deduplicated documentation cleanly. +1.
>>>>> One point I would like to add is though to add such information to the
>>>>> documentation until we actually manage our final goal
>>>>> since probably it's going to take a while to revisit/fix and make it
>>>>> fully structured with the documentation.
>>>>> If we go more conservatively, we can add such information to the new
>>>>> configurations being added from now on at least, and keeping the existing
>>>>> configurations as are.
>>>>> On Thu, 13 Feb 2020, 06:12 Dongjoon Hyun, <>
>>>>> wrote:
>>>>>> Thank you for raising the issue, Hyukjin.
>>>>>> According to the current status of discussion, it seems that we are
>>>>>> able to agree on updating the non-structured configurations and keeping
>>>>>> structured configuration AS-IS.
>>>>>> I'm +1 for the revisiting the configurations if that is our
>>>>>> direction. If there is some mismatch in structured configurations,
we may
>>>>>> fix them together.
>>>>>> Bests,
>>>>>> Dongjoon.
>>>>>> On Wed, Feb 12, 2020 at 8:08 AM Jules Damji <>
>>>>>> wrote:
>>>>>>> All are valid and valuable observations to put into practice:
>>>>>>> * structured and meaningful config names
>>>>>>> * explainable text or succinct description
>>>>>>> * easily accessible or searchable
>>>>>>> While these are aspirational but gradually doable if we make
it part
>>>>>>> of the dev and review cycle. Often meaningful config names, like
>>>>>>> come as after thought.
>>>>>>> At the AMA in Amsterdam Spark Summit last year, a few developers
>>>>>>> lamented the lack of finding Spark configs—what they do; what
they are used
>>>>>>> for; when and why; and what are their default values.
>>>>>>> Though you one fetch them programmatically, one still has to
>>>>>>> what specific config one islooking for.
>>>>>>> Cheers
>>>>>>> Jules
>>>>>>> Sent from my iPhone
>>>>>>> Pardon the dumb thumb typos :)
>>>>>>> On Feb 12, 2020, at 5:19 AM, Hyukjin Kwon <>
>>>>>>> wrote:
>>>>>>> Yeah, that's one of my point why I dont want to document this
in the
>>>>>>> guide yet.
>>>>>>> I would like to make sure dev people are on the same page that
>>>>>>> documenting is a better practice. I dont intend to force as a
>>>>>>> requirement; however, if that's pointed out, it should better
to address.
>>>>>>> On Wed, 12 Feb 2020, 21:30 Wenchen Fan, <>
>>>>>>>> In general I think it's better to have more detailed documents,
>>>>>>>> we don't have to force everyone to do it if the config name
is structured.
>>>>>>>> I would +1 to document the relationship of we can't tell
it from the config
>>>>>>>> names, e.g. spark.shuffle.service.enabled
>>>>>>>> and spark.dynamicAllocation.enabled.
>>>>>>>> On Wed, Feb 12, 2020 at 7:54 PM Hyukjin Kwon <>
>>>>>>>> wrote:
>>>>>>>>> Also, I would like to hear other people' thoughts on
here. Could I
>>>>>>>>> ask what you guys think about this in general?
>>>>>>>>> 2020년 2월 12일 (수) 오후 12:02, Hyukjin Kwon <>님이
>>>>>>>>> 작성:
>>>>>>>>>> To do that, we should explicitly document such structured
>>>>>>>>>> configuration and implicit effect, which is currently
>>>>>>>>>> I would be more than happy if we document such implied
>>>>>>>>>> relationship, *and* if we are very sure all configurations
>>>>>>>>>> structured correctly coherently.
>>>>>>>>>> Until that point, I think it might be more practical
to simply
>>>>>>>>>> document it for now.
>>>>>>>>>> > Btw, maybe off-topic, `spark.dynamicAllocation`
is having
>>>>>>>>>> another issue on practice - whether to duplicate
description between
>>>>>>>>>> configuration code and doc. I have been asked to
add description on
>>>>>>>>>> configuration code regardlessly, and existing codebase
doesn't. This
>>>>>>>>>> configuration is widely-used one.
>>>>>>>>>> This is actually something we should fix too. in
>>>>>>>>>> configuration, now we don't have such duplications
as of
>>>>>>>>>> as it
generates. We
>>>>>>>>>> should do it in other configurations.
>>>>>>>>>> 2020년 2월 12일 (수) 오전 11:47, Jungtaek Lim
>>>>>>>>>>>님이 작성:
>>>>>>>>>>> I'm looking into the case of `spark.dynamicAllocation`
and this
>>>>>>>>>>> seems to be the thing to support my voice.
>>>>>>>>>>> I don't disagree with adding "This requires
>>>>>>>>>>> spark.shuffle.service.enabled to be set." in
the description of
>>>>>>>>>>> `spark.dynamicAllocation.enabled`. This cannot
be inferred implicitly,
>>>>>>>>>>> hence it should be better to have it.
>>>>>>>>>>> Why I'm in favor of structured configuration
& implicit effect
>>>>>>>>>>> over describing everything explicitly is there.
>>>>>>>>>>> 1. There're 10 configurations (if the doc doesn't
miss any other
>>>>>>>>>>> configuration) except `spark.dynamicAllocation.enabled`,
and only 4
>>>>>>>>>>> configurations are referred in the description
>>>>>>>>>>> `spark.dynamicAllocation.enabled` - majority
of config keys are missing.
>>>>>>>>>>> 2. I think it's intentional, but the table starts
>>>>>>>>>>> with `spark.dynamicAllocation.enabled` which
talks implicitly but
>>>>>>>>>>> intuitively that if you disable this then everything
on dynamic allocation
>>>>>>>>>>> won't work. Missing majority of references on
config keys don't get it hard
>>>>>>>>>>> to understand.
>>>>>>>>>>> 3. Even `spark.dynamicAllocation` has bad case
- see
>>>>>>>>>>> `spark.dynamicAllocation.shuffleTracking.enabled`
>>>>>>>>>>> `spark.dynamicAllocation.shuffleTimeout`. It
is not respecting the
>>>>>>>>>>> structure of configuration. I think this is worse
than not explicitly
>>>>>>>>>>> mentioning the description. Let's assume the
name has
>>>>>>>>>>> been `spark.dynamicAllocation.shuffleTracking.timeout`
- isn't it intuitive
>>>>>>>>>>> that setting `spark.dynamicAllocation.shuffleTracking.enabled`
to `false`
>>>>>>>>>>> would effectively disable `spark.dynamicAllocation.shuffleTracking.timeout`?
>>>>>>>>>>> Btw, maybe off-topic, `spark.dynamicAllocation`
is having
>>>>>>>>>>> another issue on practice - whether to duplicate
description between
>>>>>>>>>>> configuration code and doc. I have been asked
to add description on
>>>>>>>>>>> configuration code regardlessly, and existing
codebase doesn't. This
>>>>>>>>>>> configuration is widely-used one.
>>>>>>>>>>> On Wed, Feb 12, 2020 at 11:22 AM Hyukjin Kwon
>>>>>>>>>>>> wrote:
>>>>>>>>>>>> Sure, adding "[DISCUSS]" is a good practice
to label it. I had
>>>>>>>>>>>> to do it although it might be "redundant"
:-) since anyone can give
>>>>>>>>>>>> feedback to any thread in Spark dev mailing
list, and discuss.
>>>>>>>>>>>> This is actually more prevailing given my
rough reading of
>>>>>>>>>>>> configuration files. I would like to see
this missing relationship as a bad
>>>>>>>>>>>> pattern, started from a personal preference.
>>>>>>>>>>>> > Personally I'd rather not think someone
won't understand
>>>>>>>>>>>> setting `.enabled` to `false` means the functionality
is disabled and
>>>>>>>>>>>> effectively it disables all sub-configurations.
>>>>>>>>>>>> > E.g. when `spark.sql.adaptive.enabled`
is `false`, all the
>>>>>>>>>>>> configurations for `spark.sql.adaptive.*`
are implicitly no-op. For me this
>>>>>>>>>>>> is pretty intuitive and the one of major
>>>>>>>>>>>> > benefits of the structured configurations.
>>>>>>>>>>>> I don't think this is a good idea we assume
for users to know
>>>>>>>>>>>> such contexts. One might think
>>>>>>>>>>>> `spark.sql.adaptive.shuffle.fetchShuffleBlocksInBatch.enabled`
>>>>>>>>>>>> partially enable the feature. It is better
to be explicit to
>>>>>>>>>>>> document since some of configurations are
even difficult for users to
>>>>>>>>>>>> confirm if it is working or not.
>>>>>>>>>>>> For instance, one might think setting
>>>>>>>>>>>> 'spark.eventLog.rolling.maxFileSize' automatically
enables rolling. Then,
>>>>>>>>>>>> they realise the log is not rolling later
after the file
>>>>>>>>>>>> size becomes bigger.
>>>>>>>>>>>> 2020년 2월 12일 (수) 오전 10:47, Jungtaek
Lim <
>>>>>>>>>>>>>님이 작성:
>>>>>>>>>>>>> I'm sorry if I miss something, but this
is ideally better to
>>>>>>>>>>>>> be started as [DISCUSS] as I haven't
seen any reference to have consensus
>>>>>>>>>>>>> on this practice.
>>>>>>>>>>>>> For me it's just there're two different
practices co-existing
>>>>>>>>>>>>> on the codebase, meaning it's closer
to the preference of individual (with
>>>>>>>>>>>>> implicitly agreeing that others have
different preferences), or it hasn't
>>>>>>>>>>>>> been discussed thoughtfully.
>>>>>>>>>>>>> Personally I'd rather not think someone
won't understand
>>>>>>>>>>>>> setting `.enabled` to `false` means the
functionality is disabled and
>>>>>>>>>>>>> effectively it disables all sub-configurations.
E.g. when
>>>>>>>>>>>>> `spark.sql.adaptive.enabled` is `false`,
all the configurations for
>>>>>>>>>>>>> `spark.sql.adaptive.*` are implicitly
no-op. For me this is pretty
>>>>>>>>>>>>> intuitive and the one of major benefits
of the structured configurations.
>>>>>>>>>>>>> If we want to make it explicit, "all"
>>>>>>>>>>>>> should have redundant part of the doc.
More redundant if the condition is
>>>>>>>>>>>>> nested. I agree this is the good step
of "be kind" but less pragmatic.
>>>>>>>>>>>>> I'd be happy to follow the consensus
we would make in this
>>>>>>>>>>>>> thread. Appreciate more voices.
>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>> Jungtaek Lim (HeartSaVioR)
>>>>>>>>>>>>> On Wed, Feb 12, 2020 at 10:36 AM Hyukjin
Kwon <
>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>> > I don't plan to document this
officially yet
>>>>>>>>>>>>>> Just to prevent confusion, I meant
I don't yet plan to
>>>>>>>>>>>>>> document the fact that we should
write the relationships in configurations
>>>>>>>>>>>>>> as a code/review guideline in
>>>>>>>>>>>>>> 2020년 2월 12일 (수) 오전 9:57,
Hyukjin Kwon <>님이
>>>>>>>>>>>>>> 작성:
>>>>>>>>>>>>>>> Hi all,
>>>>>>>>>>>>>>> I happened to review some PRs
and I noticed that some
>>>>>>>>>>>>>>> configurations don't have some
>>>>>>>>>>>>>>> necessary.
>>>>>>>>>>>>>>> To be explicit, I would like
to make sure we document the
>>>>>>>>>>>>>>> direct relationship between other
>>>>>>>>>>>>>>> in the documentation. For example,
>>>>>>>>>>>>>>> `spark.sql.adaptive.shuffle.reducePostShufflePartitions.enabled`
>>>>>>>>>>>>>>> can be only enabled when `spark.sql.adaptive.enabled`
>>>>>>>>>>>>>>> enabled. That's clearly documented.
>>>>>>>>>>>>>>> We're good in general given that
we document them in general
>>>>>>>>>>>>>>> in Apache Spark.
>>>>>>>>>>>>>>> See 'spark.task.reaper.enabled',
>>>>>>>>>>>>>>> 'spark.dynamicAllocation.enabled',
'spark.sql.parquet.filterPushdown', etc.
>>>>>>>>>>>>>>> However, I noticed such a pattern
that such information is
>>>>>>>>>>>>>>> missing in some components in
general, for example,
>>>>>>>>>>>>>>> `spark.history.fs.cleaner.*`,
`spark.history.kerberos.*` and
>>>>>>>>>>>>>>> `spark.history.ui.acls.* `
>>>>>>>>>>>>>>> I hope we all start to document
such information. Logically
>>>>>>>>>>>>>>> users can't know the relationship
and I myself
>>>>>>>>>>>>>>> had to read the codes to confirm
when I review.
>>>>>>>>>>>>>>> I don't plan to document this
officially yet because to me
>>>>>>>>>>>>>>> it looks a pretty logical request
to me; however,
>>>>>>>>>>>>>>> let me know if you guys have
some different opinions.
>>>>>>>>>>>>>>> Thanks.

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