This thread has been quiet for some time now as there are a lot of things
going on concurrently.
@Ismael Juma <ism...@juma.me.uk> @Jason Gustafson <ja...@confluent.io> what
do you think about this? Just a brief recap, we are considering exposing
the configs for each compression type in the following k-v pairs format:
compression.configs="gzip.compression.level:5, lz4.compression.level:17,
zstd.compression.level:22"
Thanks,
Jiangjie (Becket) Qin
On Thu, Feb 7, 2019 at 11:28 PM Dongjin Lee <dong...@apache.org> wrote:
> Hi Becket,
>
> Understood. You are right, introducing map type is just a clearer way, but
> not a strong prerequisite. It can be discussed later.
>
> @Committers, PMC members:
>
> Could you please give us some valuable feedbacks and suggestions for this
> topic?
>
>
> Thanks,
>
> Dongjin
>
> On Fri, Feb 1, 2019 at 11:37 AM Becket Qin <becket....@gmail.com> wrote:
>
> > Hi Dongjin,
> >
> > Thanks for the reply. I agree that implementation wise, it is clearer to
> > add a new "Map" config type. However, practically speaking I don't think
> > this KIP strongly depends on that. As long as we follow the same string
> > format in the configuration for all those map-like configurations,
> whether
> > to have a Map config type or not seems not that important.
> >
> > Given that the existing configuration uses the format of
> > "KEY:VALUE[,KEY:VALUE]", we could just use this string format.
> >
> > Thanks,
> >
> > Jiangjie (Becket) Qin
> >
> > On Thu, Jan 31, 2019 at 7:47 PM Dongjin Lee <dong...@apache.org> wrote:
> >
> > > Mickael,
> > >
> > > It seems like the majority of the community agrees that the new config
> > > scheme proposed by Becket is much better. However, we still need
> another
> > > KIP to support this kind of config; it is different from the case of
> > > `listener.security.protocol.map,` which is just a concatenation of
> > > available settings (i.e., string type.) For Becket's idea, we need to
> add
> > > support for the key-value style.
> > >
> > > It seems like we need advice from a committer, whether to add a new
> > > prerequisite KIP for the map type configuration to implement Becket's
> > idea.
> > >
> > > Committers:
> > >
> > > Could you give us some advice on this problem?
> > >
> > > Best,
> > > Dongjin
> > >
> > > On Wed, Jan 30, 2019 at 11:30 PM Mickael Maison <
> > mickael.mai...@gmail.com>
> > > wrote:
> > >
> > > > Thanks, that's a very interesting KIP!
> > > >
> > > > I agree with Becket that a clearer config format is likely to help.
> > > > Have you considered using a config format similar to listeners (as
> > > > described in the "Updating SSL Keystore of an Existing Listener" in
> > > > the Kafka docs)?
> > > >
> > > > Also worth noting that we already have configs that effectively take
> a
> > > > map, for example: listener.security.protocol.map so not sure if we
> > > > need an additional KIP
> > > >
> > > > On Wed, Jan 30, 2019 at 5:22 AM Dongjin Lee <dong...@apache.org>
> > wrote:
> > > > >
> > > > > Hello.
> > > > >
> > > > > Do you have any idea on Becket's Idea of new config format (example
> > > > below)?
> > > > >
> > > > > ```
> > > > > compression.config="gzip.compression.level=5,
> > lz4.compression.level=17,
> > > > > zstd.compression.level=22"
> > > > > ```
> > > > >
> > > > > It requires some additional KIP for supporting new config format
> > (map),
> > > > but
> > > > > it can significantly simplify the configuration with flexibility
> and
> > > > > extensibility. If you prefer this way, I hope to carry the ball.
> > > > >
> > > > > If not, please give me an opinion here or the voting thread.
> > > > >
> > > > > Thanks,
> > > > > Dongjin
> > > > >
> > > > >
> > > > > On Fri, Jan 25, 2019 at 1:25 AM Dongjin Lee <dong...@apache.org>
> > > wrote:
> > > > >
> > > > > > Hi Becket,
> > > > > >
> > > > > > Thank you for your opinion. Frankly, I have no strong opinion on
> > > > > > configuration name. In this problem, I will follow the
> community's
> > > > choice.
> > > > > > (I like your idea in that it has a notion of 'scope' per
> > compression
> > > > codec.
> > > > > > However, it should be implemented on top of new config type like
> > Map;
> > > > It
> > > > > > will require another KIP as a prerequisite, but if the community
> > > prefer
> > > > > > this way, I will take the task.)
> > > > > >
> > > > > > (One minor correction: the one who thought 'producer' compression
> > > > config
> > > > > > would cause a problem at broker was me, not Ismael - and Ismael
> > > > reassured
> > > > > > me there will be no problem with it.)
> > > > > >
> > > > > > To All,
> > > > > >
> > > > > > How about Becket's idea of 'compression.config' option?
> > > > > >
> > > > > > Best,
> > > > > > Dongjin
> > > > > >
> > > > > > On Wed, Jan 23, 2019 at 1:16 PM Becket Qin <becket....@gmail.com
> >
> > > > wrote:
> > > > > >
> > > > > >> Hi Dongjin,
> > > > > >>
> > > > > >> Thanks for the KIP and sorry for being a bit late on the
> > discussion.
> > > > > >>
> > > > > >> It makes sense to expose the configuration for compression
> types.
> > > But
> > > > I am
> > > > > >> wondering if there is a better way to do that than what proposed
> > in
> > > > the
> > > > > >> KIP. What I feel confusing is that we are effectively sharing
> the
> > > > > >> configuration across different compression types, the meaning of
> > the
> > > > > >> configuration are actually kind of different depending on the
> > > > compression
> > > > > >> type. This will end up with issues like what Ismael has brought
> up
> > > > > >> earlier.
> > > > > >> Say if the broker has compression type of producer (this may
> > result
> > > in
> > > > > >> mixed compression type in the same topic), and for some reason
> the
> > > > broker
> > > > > >> needs to re-compress the topic (e.g. due to log compaction), a
> > > single
> > > > > >> topic
> > > > > >> level compression config may not work, because a valid
> compression
> > > > level
> > > > > >> for lz4 maybe invalid for gzip.
> > > > > >>
> > > > > >> One alternative I am thinking is to provide a
> "compression.config"
> > > > > >> configuration, inside which it specifies configuration used by
> > each
> > > > > >> specific compression type as k-v pairs. The format could use
> some
> > > name
> > > > > >> space as well. For example,
> > > > > >>
> > > > > >>
> > > > > >>
> > > >
> > >
> >
> compression.config="gzip.compression.level=5,lz4.compression.level=17,zstd.compression.level=22".
> > > > > >>
> > > > > >> Each compression type will just pick whatever configuration they
> > > need
> > > > from
> > > > > >> the k-v pairs defined in this config.
> > > > > >>
> > > > > >> Besides clarity, some other benefits are:
> > > > > >> 1. Extensibility, we don't have to add more configuration when
> we
> > > add
> > > > new
> > > > > >> compression types, or expose new config for a particular
> > compression
> > > > type.
> > > > > >> 2. Even for the same config, different compression type may have
> > > > different
> > > > > >> terminologies. With the approach we can honor those
> terminologies
> > > > instead
> > > > > >> of shoehorning them into the same configuration name.
> > > > > >>
> > > > > >> What do you think?
> > > > > >>
> > > > > >> Thanks,
> > > > > >>
> > > > > >> Jiangjie (Becket) Qin
> > > > > >>
> > > > > >>
> > > > > >>
> > > > > >>
> > > > > >>
> > > > > >> On Wed, Jan 23, 2019 at 12:07 AM Dongjin Lee <
> dong...@apache.org>
> > > > wrote:
> > > > > >>
> > > > > >> > Hello. I just fixed the draft implementation, with rebasing
> onto
> > > the
> > > > > >> latest
> > > > > >> > trunk. The KIP was also restored.
> > > > > >> >
> > > > > >> > Please have a look, and if there is no major problem, please
> > vote
> > > > to the
> > > > > >> > voting thread. You know, KIP freeze for 2.2.0 is almost
> > imminent.
> > > > > >> >
> > > > > >> > Thanks,
> > > > > >> > Dongjin
> > > > > >> >
> > > > > >> > On Tue, Jan 22, 2019 at 1:04 AM Ismael Juma <
> ism...@juma.me.uk>
> > > > wrote:
> > > > > >> >
> > > > > >> > > Thanks!
> > > > > >> > >
> > > > > >> > > Ismael
> > > > > >> > >
> > > > > >> > > On Mon, Jan 21, 2019 at 6:02 AM Dongjin Lee <
> > dong...@apache.org
> > > >
> > > > > >> wrote:
> > > > > >> > >
> > > > > >> > > > 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>*
> > > > > >> > > >
> > > > > >> > >
> > > > > >> >
> > > > > >> >
> > > > > >> > --
> > > > > >> > *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>*
>
