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>*
