Hi Ismael,
After reviewing `LogValidator#validateMessagesAndAssignOffsetsCompressed`,
yes, you are right. If source codec and target codec is identical and the
magic is above 0, the broker can do an in-place assignment, without
recompressing. Sorry for my misunderstanding.
Since we don't need `compression.[gzip,lz4,zstd].level` and
`compression.[gzip,snappy,lz4].buffer.size` anymore, I will revert those
changes and update the KIP with the recent discussions. I will complete it
in 48 hours from now.
Thanks,
Dongjin
On Mon, Jan 21, 2019 at 4:18 PM Dongjin Lee <dong...@apache.org> wrote:
> I see. Let me have a check. If not needed, of course, we don't have to
> waste on configuration options.
>
> Since the KIP deadline is imminent, I just opened the voting thread. Let's
> continue the discussion here.
>
> Best,
> Dongjin
>
> On Mon, Jan 21, 2019 at 1:30 AM Ismael Juma <ism...@juma.me.uk> wrote:
>
>> Hi Dongjin,
>>
>> When the compression type is "producer", then the broker doesn't
>> recompress
>> though. Thinking about it some more, there are some uncommon cases where
>> recompression does happen (the old (and hopefully hardly used by now)
>> message format == 0 and some edge cases), so it is a good point you
>> raised.
>>
>> It's a bit unfortunate to add so many topic configs for cases that
>> probably
>> don't matter. That is, if you are using "producer" compression, you
>> probably don't need to configure these settings and can live with the
>> defaults. Perhaps we should only support the topic config for the cases
>> where you are actually recompressing in the broker.
>>
>> What do you think? I'd be interested in other people's thoughts too.
>>
>> Ismael
>>
>> On Sun, Jan 20, 2019 at 2:14 AM Dongjin Lee <dong...@apache.org> wrote:
>>
>> > Hi Ismael,
>> >
>> > It seems like it needs more explanation. Here is the detailed reasoning.
>> >
>> > You know, topic and broker's 'compression.type' allows 'uncompressed',
>> > 'producer' with standard codecs (i.e., gzip, snappy, lz4, zstd.) And
>> this
>> > configuration is used by the broker in the re-compressing process after
>> > offset assignment. After this feature, the new configs,
>> 'compression.level'
>> > and 'compression.buffer.size', also will be used in this process.
>> >
>> > The problem arises when given topic's compression type (whether it was
>> > inherited from broker's configuration or explicitly set) is 'producer.'
>> > With this setting, the compression codec to be used is decided by the
>> > producer client. Since there is no way to restore the compression level
>> and
>> > buffer size from the message, we can take the following strategies:
>> >
>> > 1. Just use given 'compression.level' and 'compression.buffer.size'
>> > settings.
>> >
>> > It will cause so many errors. Let's imagine the case of topic's
>> > configuration is { compression.type=producer, compression.level=10,
>> > compression.buffer.size=8192 }. In this case, all producers with gzip or
>> > lz4 compressed messages will result in an error. (gzip doesn't allow
>> > compression level 10, and lz4 also for a buffer size of 8192.)
>> >
>> > 2. Extend the message format to include compression configurations.
>> >
>> > With this strategy, we need to change the message format - it's a too
>> big
>> > change.
>> >
>> > 3. If topic's compression.type is 'producer', use the default
>> configuration
>> > for the given codec.
>> >
>> > With this strategy, allowing fine-grained compression configuration is
>> > meaningless.
>> >
>> > For the above reasons, I think the only alternative is providing options
>> > that can be used when the topic's 'compression.type' is 'producer.' In
>> > other words, adding compression.[gzip, lz4, zstd].level and
>> > compression.[gzip.snappy.lz4].buffer.size options - and it is what I
>> did in
>> > the last modification.
>> >
>> > (wait, the reasoning above should be included in the KIP in the rejected
>> > alternatives section, isn't it?)
>> >
>> > Thanks,
>> > Dongjin
>> >
>> > On Sun, Jan 20, 2019 at 2:33 AM Ismael Juma <ism...@juma.me.uk> wrote:
>> >
>> > > Hi Dongjin,
>> > >
>> > > For topic level, you can only have a single compression type so the
>> way
>> > it
>> > > was before was fine, right? The point you raise is how to set broker
>> > > defaults that vary depending on the compression type, correct?
>> > >
>> > > Ismael
>> > >
>> > > On Mon, Jan 14, 2019 at 10:18 AM Dongjin Lee <dong...@apache.org>
>> wrote:
>> > >
>> > > > I just realized that there was a missing hole in the KIP, so I fixed
>> > it.
>> > > > The draft implementation will be updated soon.
>> > > >
>> > > > In short, the proposed change did not regard the case of the topic
>> or
>> > > > broker's 'compression.type' is 'producer'; in this case, the broker
>> has
>> > > to
>> > > > handle all kinds of the supported codec. So I added additional
>> options
>> > > > (compression.[gzip,snappy,lz4, zstd].level,
>> > compression.[gzip,snappy,lz4,
>> > > > zstd].buffer.size) with handling routines.
>> > > >
>> > > > Please have a look when you are free.
>> > > >
>> > > > Thanks,
>> > > > Dongjin
>> > > >
>> > > > On Mon, Jan 7, 2019 at 6:23 AM Dongjin Lee <dong...@apache.org>
>> wrote:
>> > > >
>> > > > > Thanks for pointing out Ismael. It's now updated.
>> > > > >
>> > > > > Best,
>> > > > > Dongjin
>> > > > >
>> > > > > On Mon, Jan 7, 2019 at 4:36 AM Ismael Juma <isma...@gmail.com>
>> > wrote:
>> > > > >
>> > > > >> Thanks Dongjin. One minor suggestion: we should mention that the
>> > > broker
>> > > > >> side configs are also topic configs (i.e. can be set for a given
>> > > topic).
>> > > > >>
>> > > > >> Ismael
>> > > > >>
>> > > > >> On Sun, Jan 6, 2019, 10:37 AM Dongjin Lee <dong...@apache.org
>> > wrote:
>> > > > >>
>> > > > >> > Happy new year.
>> > > > >> >
>> > > > >> > I just updated the title and contents of KIP and Jira issue,
>> with
>> > > > >> updated
>> > > > >> > draft implementation. Now both of compression level and buffer
>> > size
>> > > > >> options
>> > > > >> > are available to producer and broker configuration. You can
>> check
>> > > the
>> > > > >> > updated KIP from modified URL:
>> > > > >> >
>> > > > >> >
>> > > > >> >
>> > > > >>
>> > > >
>> > >
>> >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-390%3A+Allow+fine-grained+configuration+for+compression
>> > > > >> >
>> > > > >> > Please have a look when you are free.
>> > > > >> >
>> > > > >> > Thanks,
>> > > > >> > Dongjin
>> > > > >> >
>> > > > >> > On Mon, Dec 3, 2018 at 12:50 AM Ismael Juma <isma...@gmail.com
>> >
>> > > > wrote:
>> > > > >> >
>> > > > >> > > The updated title sounds fine to me.
>> > > > >> > >
>> > > > >> > > Ismael
>> > > > >> > >
>> > > > >> > > On Sun, Dec 2, 2018, 5:25 AM Dongjin Lee <dong...@apache.org
>> > > wrote:
>> > > > >> > >
>> > > > >> > > > Hi Ismael,
>> > > > >> > > >
>> > > > >> > > > Got it. Your direction is perfectly reasonable. I am now
>> > > updating
>> > > > >> the
>> > > > >> > KIP
>> > > > >> > > > document and the implementation.
>> > > > >> > > >
>> > > > >> > > > By allowing the buffer/block size to be configurable, it
>> would
>> > > be
>> > > > >> > better
>> > > > >> > > to
>> > > > >> > > > update the title of the KIP like 'Allow fine-grained
>> > > configuration
>> > > > >> for
>> > > > >> > > > compression'. Is that right?
>> > > > >> > > >
>> > > > >> > > > @Other committers:
>> > > > >> > > >
>> > > > >> > > > Is there any other opinion on allowing the buffer/block
>> size
>> > to
>> > > be
>> > > > >> > > > configurable?
>> > > > >> > > >
>> > > > >> > > > Thanks,
>> > > > >> > > > Dongjin
>> > > > >> > > >
>> > > > >> > > > On Thu, Nov 29, 2018 at 1:45 AM Ismael Juma <
>> > ism...@juma.me.uk>
>> > > > >> wrote:
>> > > > >> > > >
>> > > > >> > > > > Hi Dongjin,
>> > > > >> > > > >
>> > > > >> > > > > To clarify, I mean a broker topic config with regards to
>> > point
>> > > > 1.
>> > > > >> As
>> > > > >> > > you
>> > > > >> > > > > know, compression can be done by the producer and/or by
>> the
>> > > > >> broker.
>> > > > >> > The
>> > > > >> > > > > default is for the broker to just use whatever
>> compression
>> > was
>> > > > >> used
>> > > > >> > by
>> > > > >> > > > the
>> > > > >> > > > > producer, but this can be changed by the user on a per
>> topic
>> > > > >> basis.
>> > > > >> > It
>> > > > >> > > > > seems like it would make sense for the configs to be .
>> > > > consistent
>> > > > >> > > between
>> > > > >> > > > > producer and broker.
>> > > > >> > > > >
>> > > > >> > > > > For point 2, I haven't looked at the implementation, but
>> we
>> > > > could
>> > > > >> do
>> > > > >> > it
>> > > > >> > > > in
>> > > > >> > > > > the `CompressionType` enum by invoking the right
>> constructor
>> > > or
>> > > > >> > > > retrieving
>> > > > >> > > > > the default value via a constant (if defined). That's an
>> > > > >> > implementation
>> > > > >> > > > > detail and can be discussed in the PR. The more general
>> > point
>> > > is
>> > > > >> to
>> > > > >> > > rely
>> > > > >> > > > on
>> > > > >> > > > > the library defaults instead of choosing one ourselves.
>> > > > >> > > > >
>> > > > >> > > > > For point 3, I'm in favour of doing that in this KIP.
>> > > > >> > > > >
>> > > > >> > > > > Ismael
>> > > > >> > > > >
>> > > > >> > > > > On Wed, Nov 28, 2018 at 7:01 AM Dongjin Lee <
>> > > dong...@apache.org
>> > > > >
>> > > > >> > > wrote:
>> > > > >> > > > >
>> > > > >> > > > > > Thank you Ismael, here are the answers:
>> > > > >> > > > > >
>> > > > >> > > > > > *1. About topic config*
>> > > > >> > > > > >
>> > > > >> > > > > > After some consideration, I concluded that topic config
>> > > > doesn't
>> > > > >> > need
>> > > > >> > > to
>> > > > >> > > > > > support compression.level. Here is why: since the
>> > > compression
>> > > > is
>> > > > >> > > > > conducted
>> > > > >> > > > > > by the client, the one who can select the best
>> compression
>> > > > >> level is
>> > > > >> > > the
>> > > > >> > > > > > client itself. Let us assume that the compression
>> level is
>> > > set
>> > > > >> at
>> > > > >> > the
>> > > > >> > > > > topic
>> > > > >> > > > > > config level. In that case, there is a possibility that
>> > the
>> > > > >> > > compression
>> > > > >> > > > > > level is not optimal for some producers. Actually,
>> Kafka's
>> > > go
>> > > > >> > client
>> > > > >> > > > also
>> > > > >> > > > > > supports compression level functionality for the
>> producer
>> > > > config
>> > > > >> > > only.
>> > > > >> > > > > > <
>> https://github.com/Shopify/sarama/blob/master/config.go>
>> > > > >> (wait,
>> > > > >> > do
>> > > > >> > > we
>> > > > >> > > > > > need
>> > > > >> > > > > > to add this reasoning in the KIP, rejected alternatives
>> > > > >> section?)
>> > > > >> > > > > >
>> > > > >> > > > > > *2. About default level*
>> > > > >> > > > > >
>> > > > >> > > > > > As of current draft implementation, the default
>> > compression
>> > > is
>> > > > >> set
>> > > > >> > on
>> > > > >> > > > the
>> > > > >> > > > > > CompressionType enum. Of course, changing this strategy
>> > into
>> > > > >> > relying
>> > > > >> > > > on a
>> > > > >> > > > > > method from the library to pick the default compression
>> > > level
>> > > > >> seems
>> > > > >> > > > > > possible, like `GZIPBlockOutputStream` does. In this
>> case,
>> > > we
>> > > > >> need
>> > > > >> > to
>> > > > >> > > > add
>> > > > >> > > > > > similar wrapper class for zstd and modify lz4 the
>> wrapper
>> > > > also.
>> > > > >> Add
>> > > > >> > > to
>> > > > >> > > > > > this, it seems like we need to explicitly state that we
>> > > follow
>> > > > >> the
>> > > > >> > > > > default
>> > > > >> > > > > > compression level of the codec in the documentation. Is
>> > this
>> > > > >> what
>> > > > >> > you
>> > > > >> > > > > > intended?
>> > > > >> > > > > >
>> > > > >> > > > > > *3. Whether to allow the buffer/block size to be
>> > > configurable*
>> > > > >> > > > > >
>> > > > >> > > > > > Well, As of current draft implementation, the lz4
>> level is
>> > > > >> > > implemented
>> > > > >> > > > as
>> > > > >> > > > > > block size; this is caused by my misunderstanding on
>> lz4.
>> > > > After
>> > > > >> > > > reviewing
>> > > > >> > > > > > lz4 today, I found that it also supports compression
>> level
>> > > of
>> > > > >> 1~16
>> > > > >> > > > > > (default: 1), not block size. I will fix it in this
>> > weekend
>> > > by
>> > > > >> > > updating
>> > > > >> > > > > the
>> > > > >> > > > > > wrapper class.
>> > > > >> > > > > >
>> > > > >> > > > > > For the problem of the buffer/block size, I have no
>> strong
>> > > > >> opinion.
>> > > > >> > > If
>> > > > >> > > > > the
>> > > > >> > > > > > community needs it, I will do it all together. How do
>> you
>> > > > think?
>> > > > >> > > > > >
>> > > > >> > > > > > In short, it seems like I need to update the KIP
>> document
>> > > for
>> > > > >> issue
>> > > > >> > > #1
>> > > > >> > > > > and
>> > > > >> > > > > > update the compression wrapper for issue #2, #3. Is
>> this
>> > > okay?
>> > > > >> > > > > >
>> > > > >> > > > > > Thanks,
>> > > > >> > > > > > Dongjin
>> > > > >> > > > > >
>> > > > >> > > > > > On Wed, Nov 28, 2018 at 12:34 AM Ismael Juma <
>> > > > isma...@gmail.com
>> > > > >> >
>> > > > >> > > > wrote:
>> > > > >> > > > > >
>> > > > >> > > > > > > Thanks for the KIP, this is helpful. A few
>> questions:
>> > > > >> > > > > > >
>> > > > >> > > > > > > 1. Have we considered whether we want to allow a
>> similar
>> > > > topic
>> > > > >> > > > config?
>> > > > >> > > > > > > 2. Can we rely on a method from the library to pick
>> the
>> > > > >> default
>> > > > >> > > > > > compression
>> > > > >> > > > > > > level if compression.level is not set? We do it for
>> gzip
>> > > and
>> > > > >> it
>> > > > >> > > would
>> > > > >> > > > > > seem
>> > > > >> > > > > > > reasonable to do something similar for the other
>> > > compression
>> > > > >> > > > libraries.
>> > > > >> > > > > > > 3. Do we want to allow the buffer/block size to be
>> > > > >> configurable?
>> > > > >> > > This
>> > > > >> > > > > has
>> > > > >> > > > > > > an impact on memory usage and people may want to
>> trade
>> > > > >> > compression
>> > > > >> > > > for
>> > > > >> > > > > > > less/more memory in some cases. For example, the
>> default
>> > > for
>> > > > >> LZ4
>> > > > >> > is
>> > > > >> > > > > 64KB
>> > > > >> > > > > > > which is a bit high.
>> > > > >> > > > > > >
>> > > > >> > > > > > > Ismael
>> > > > >> > > > > > >
>> > > > >> > > > > > > On Sun, Nov 18, 2018, 2:07 PM Dongjin Lee <
>> > > > dong...@apache.org
>> > > > >> > > wrote:
>> > > > >> > > > > > >
>> > > > >> > > > > > > > Hello dev,
>> > > > >> > > > > > > >
>> > > > >> > > > > > > > I hope to initiate the discussion of KIP-390: Add
>> > > producer
>> > > > >> > option
>> > > > >> > > > to
>> > > > >> > > > > > > adjust
>> > > > >> > > > > > > > compression level
>> > > > >> > > > > > > > <
>> > > > >> > > > > > > >
>> > > > >> > > > > > >
>> > > > >> > > > > >
>> > > > >> > > > >
>> > > > >> > > >
>> > > > >> > >
>> > > > >> >
>> > > > >>
>> > > >
>> > >
>> >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-390%3A+Add+producer+option+to+adjust+compression+level
>> > > > >> > > > > > > > >.
>> > > > >> > > > > > > > All feedbacks will be highly appreciated.
>> > > > >> > > > > > > >
>> > > > >> > > > > > > > Best,
>> > > > >> > > > > > > > Dongjin
>> > > > >> > > > > > > >
>> > > > >> > > > > > > > --
>> > > > >> > > > > > > > *Dongjin Lee*
>> > > > >> > > > > > > >
>> > > > >> > > > > > > > *A hitchhiker in the mathematical world.*
>> > > > >> > > > > > > >
>> > > > >> > > > > > > > *github: <http://goog_969573159/>
>> > > github.com/dongjinleekr
>> > > > >> > > > > > > > <http://github.com/dongjinleekr>linkedin:
>> > > > >> > > > > > > kr.linkedin.com/in/dongjinleekr
>> > > > >> > > > > > > > <http://kr.linkedin.com/in/dongjinleekr
>> >slideshare:
>> > > > >> > > > > > > > www.slideshare.net/dongjinleekr
>> > > > >> > > > > > > > <http://www.slideshare.net/dongjinleekr>*
>> > > > >> > > > > > > >
>> > > > >> > > > > > >
>> > > > >> > > > > >
>> > > > >> > > > > >
>> > > > >> > > > > > --
>> > > > >> > > > > > *Dongjin Lee*
>> > > > >> > > > > >
>> > > > >> > > > > > *A hitchhiker in the mathematical world.*
>> > > > >> > > > > > *github: <http://goog_969573159/>
>> github.com/dongjinleekr
>> > > > >> > > > > > <https://github.com/dongjinleekr>linkedin:
>> > > > >> > > > > kr.linkedin.com/in/dongjinleekr
>> > > > >> > > > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > > > >> > > > > > speakerdeck.com/dongjin
>> > > > >> > > > > > <https://speakerdeck.com/dongjin>*
>> > > > >> > > > > >
>> > > > >> > > > >
>> > > > >> > > >
>> > > > >> > > >
>> > > > >> > > > --
>> > > > >> > > > *Dongjin Lee*
>> > > > >> > > >
>> > > > >> > > > *A hitchhiker in the mathematical world.*
>> > > > >> > > > *github: <http://goog_969573159/>github.com/dongjinleekr
>> > > > >> > > > <https://github.com/dongjinleekr>linkedin:
>> > > > >> > > kr.linkedin.com/in/dongjinleekr
>> > > > >> > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > > > >> > > > speakerdeck.com/dongjin
>> > > > >> > > > <https://speakerdeck.com/dongjin>*
>> > > > >> > > >
>> > > > >> > >
>> > > > >> >
>> > > > >> >
>> > > > >> > --
>> > > > >> > *Dongjin Lee*
>> > > > >> >
>> > > > >> > *A hitchhiker in the mathematical world.*
>> > > > >> > *github: <http://goog_969573159/>github.com/dongjinleekr
>> > > > >> > <https://github.com/dongjinleekr>linkedin:
>> > > > >> kr.linkedin.com/in/dongjinleekr
>> > > > >> > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > > > >> > speakerdeck.com/dongjin
>> > > > >> > <https://speakerdeck.com/dongjin>*
>> > > > >> >
>> > > > >>
>> > > > >
>> > > > >
>> > > > > --
>> > > > > *Dongjin Lee*
>> > > > >
>> > > > > *A hitchhiker in the mathematical world.*
>> > > > > *github: <http://goog_969573159/>github.com/dongjinleekr
>> > > > > <https://github.com/dongjinleekr>linkedin:
>> > > > kr.linkedin.com/in/dongjinleekr
>> > > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > > > speakerdeck.com/dongjin
>> > > > > <https://speakerdeck.com/dongjin>*
>> > > > >
>> > > >
>> > > >
>> > > > --
>> > > > *Dongjin Lee*
>> > > >
>> > > > *A hitchhiker in the mathematical world.*
>> > > > *github: <http://goog_969573159/>github.com/dongjinleekr
>> > > > <https://github.com/dongjinleekr>linkedin:
>> > > kr.linkedin.com/in/dongjinleekr
>> > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > > > speakerdeck.com/dongjin
>> > > > <https://speakerdeck.com/dongjin>*
>> > > >
>> > >
>> >
>> >
>> > --
>> > *Dongjin Lee*
>> >
>> > *A hitchhiker in the mathematical world.*
>> > *github: <http://goog_969573159/>github.com/dongjinleekr
>> > <https://github.com/dongjinleekr>linkedin:
>> kr.linkedin.com/in/dongjinleekr
>> > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck:
>> > speakerdeck.com/dongjin
>> > <https://speakerdeck.com/dongjin>*
>> >
>>
>
>
> --
> *Dongjin Lee*
>
> *A hitchhiker in the mathematical world.*
> *github: <http://goog_969573159/>github.com/dongjinleekr
> <https://github.com/dongjinleekr>linkedin: kr.linkedin.com/in/dongjinleekr
> <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: speakerdeck.com/dongjin
> <https://speakerdeck.com/dongjin>*
>
--
*Dongjin Lee*
*A hitchhiker in the mathematical world.*
*github: <http://goog_969573159/>github.com/dongjinleekr
<https://github.com/dongjinleekr>linkedin: kr.linkedin.com/in/dongjinleekr
<https://kr.linkedin.com/in/dongjinleekr>speakerdeck: speakerdeck.com/dongjin
<https://speakerdeck.com/dongjin>*
