Jason and Ismael, It seems like the only thing we need to regard if we define a new error code (i.e., UNSUPPORTED_COMPRESSION_TYPE) would be the implementation of the other language clients, right? At least, this strategy causes any problem for Java client. Do I understand correctly?
Thanks, Dongjin On Wed, Aug 22, 2018 at 5:43 PM Dongjin Lee <[email protected]> wrote: > Jason, > > > I think we would only use this error code when we /know/ that zstd was > in use and the client doesn't support it? This is true if either 1) the > message needs down-conversion and we encounter a zstd compressed message, > or 2) if the topic is explicitly configured to use zstd. > > Yes, it is right. And you know, the case 1 includes 1.a) old clients' > request v0, v1 records or 1.b) implicit zstd, the compression type of > "producer" with Zstd compressed data. > > > However, if the compression type is set to "producer," then the fetched > data may or may not be compressed with zstd. In this case, we return the > data to the client and expect it to fail parsing. Is that correct? > > Exactly. > > Following your message, I reviewed the implementation of > `KafkaApis#handleFetchRequest,` which handles the fetch request. And found > that the information we can use is like the following: > > 1. Client's fetch request version. (`versionId` variable) > 2. Log's compression type. (`logConfig` variable) > > We can't detect the actual compression type of the data, unless we inspect > the `RecordBatch` included in the `Records` instance (i.e., > `unconvertedRecords` variable.) Since it requires some performance issue, > it is not our option - in short, we can't be sure if given chunks of data > are compressed with zstd or not. > > So, conclusion: we can return an error in the case of 1.a and 2 easily, > with the information above. In the case 1.b (implicit zstd), we can just > return the data by do nothing special and expect it to fail parsing. > > Thanks, > Dongjin > > On Wed, Aug 22, 2018 at 12:02 PM Ismael Juma <[email protected]> wrote: > >> Jason, that's an interesting point regarding the Java client. Do we know >> what clients in other languages do in these cases? >> >> Ismael >> >> On Tue, 21 Aug 2018, 17:30 Jason Gustafson, <[email protected]> wrote: >> >> > Hi Dongjin, >> > >> > One of the complications is that old versions of the API will not >> expect a >> > new error code. However, since we expect this to be a fatal error anyway >> > for old clients, it may still be more useful to return the correct error >> > code. For example, the Kafka clients use the following code to convert >> the >> > error code: >> > >> > public static Errors forCode(short code) { >> > Errors error = codeToError.get(code); >> > if (error != null) { >> > return error; >> > } else { >> > log.warn("Unexpected error code: {}.", code); >> > return UNKNOWN_SERVER_ERROR; >> > } >> > } >> > >> > If we return an unsupported error code, it will be converted to an >> UNKNOWN >> > error, but at least we will get the message in the log with the correct >> > code. That seems preferable to returning a misleading error code. So I >> > wonder if we can use the new UNSUPPORTED_COMPRESSION_TYPE error even for >> > older versions. >> > >> > Also, one question just to check my understanding. I think we would only >> > use this error code when we /know/ that zstd was in use and the client >> > doesn't support it? This is true if either 1) the message needs >> > down-conversion and we encounter a zstd compressed message, or 2) if the >> > topic is explicitly configured to use zstd. However, if the compression >> > type is set to "producer," then the fetched data may or may not be >> > compressed with zstd. In this case, we return the data to the client and >> > expect it to fail parsing. Is that correct? >> > >> > Thanks, >> > Jason >> > >> > >> > >> > On Tue, Aug 21, 2018 at 9:08 AM, Dongjin Lee <[email protected]> >> wrote: >> > >> > > Ismael, Jason and all, >> > > >> > > I rewrote the backward compatibility strategy & its alternatives like >> > > following, based on Ismael & Jason's comments. Since it is not >> updated to >> > > the wiki yet, don't hesitate to give me a message if you have any >> opinion >> > > on it. >> > > >> > > ``` >> > > *Backward Compatibility* >> > > >> > > We need to establish some backward-compatibility strategy for the >> case an >> > > old client subscribes a topic using ZStandard implicitly (i.e., >> > > 'compression.type' configuration of given topic is 'producer' and the >> > > producer compressed the records with ZStandard). We have the following >> > > options for this situation: >> > > >> > > *A. Support ZStandard to the old clients which can understand v0, v1 >> > > messages only.* >> > > >> > > This strategy necessarily requires the down-conversion of v2 message >> > > compressed with Zstandard into v0 or v1 messages, which means a >> > > considerable performance degradation. So we rejected this strategy. >> > > >> > > *B. Bump the API version and support only v2-available clients* >> > > >> > > With this approach, we can message the old clients that they are old >> and >> > > should be upgraded. However, there are still several options for the >> > Error >> > > code. >> > > >> > > *B.1. INVALID_REQUEST (42)* >> > > >> > > This option gives the client so little information; the user can be >> > > confused about why the client worked correctly in the past suddenly >> > > encounters a problem. So we rejected this strategy. >> > > >> > > *B.2. CORRUPT_MESSAGE (2)* >> > > >> > > This option gives inaccurate information; the user can be surprised >> and >> > > misunderstand that the log files are broken in some way. So we >> rejected >> > > this strategy. >> > > >> > > *B.3 UNSUPPORTED_FOR_MESSAGE_FORMAT (43)* >> > > >> > > The advantage of this approach is we don't need to define a new error >> > code; >> > > we can reuse it and that's all. >> > > >> > > The disadvantage of this approach is that it is also a little bit >> vague; >> > > This error code is defined as a work for KIP-98[^1] and now returned >> in >> > the >> > > transaction error. >> > > >> > > *B.4. UNSUPPORTED_COMPRESSION_TYPE (new)* >> > > >> > > The advantage of this approach is that it is clear and provides an >> exact >> > > description. The disadvantage is we need to add a new error code. >> > > ``` >> > > >> > > *It seems like what we need to choose is now so clear: >> > > UNSUPPORTED_FOR_MESSAGE_FORMAT (B.3) or UNSUPPORTED_COMPRESSION_TYPE >> > > (B.4).* >> > > The first one doesn't need a new error message but the latter is more >> > > explicit. Which one do you prefer? Since all of you have much more >> > > experience and knowledge than me, I will follow your decision. The >> wiki >> > > page will be updated following the decision also. >> > > >> > > Best, >> > > Dongjin >> > > >> > > [^1]: https://issues.apache.org/jira/browse/KAFKA-4990 >> > > >> > > On Sun, Aug 19, 2018 at 4:58 AM Ismael Juma <[email protected]> >> wrote: >> > > >> > > > Sounds reasonable to me. >> > > > >> > > > Ismael >> > > > >> > > > On Sat, 18 Aug 2018, 12:20 Jason Gustafson, <[email protected]> >> > wrote: >> > > > >> > > > > Hey Ismael, >> > > > > >> > > > > Your summary looks good to me. I think it might also be a good >> idea >> > to >> > > > add >> > > > > a new UNSUPPORTED_COMPRESSION_TYPE error code to go along with the >> > > > version >> > > > > bumps. We won't be able to use it for old api versions since the >> > > clients >> > > > > will not understand it, but we can use it going forward so that >> we're >> > > not >> > > > > stuck in a similar situation with a new message format and a new >> > codec >> > > to >> > > > > support. Another option is to use UNSUPPORTED_FOR_MESSAGE_FORMAT, >> but >> > > it >> > > > is >> > > > > not as explicit. >> > > > > >> > > > > -Jason >> > > > > >> > > > > On Fri, Aug 17, 2018 at 5:19 PM, Ismael Juma <[email protected]> >> > > wrote: >> > > > > >> > > > > > Hi Dongjin and Jason, >> > > > > > >> > > > > > I would agree. My summary: >> > > > > > >> > > > > > 1. Support zstd with message format 2 only. >> > > > > > 2. Bump produce and fetch request versions. >> > > > > > 3. Provide broker errors whenever possible based on the request >> > > version >> > > > > and >> > > > > > rely on clients for the cases where the broker can't validate >> > > > efficiently >> > > > > > (example message format 2 consumer that supports the latest >> fetch >> > > > version >> > > > > > but doesn't support zstd). >> > > > > > >> > > > > > If there's general agreement on this, I suggest we update the >> KIP >> > to >> > > > > state >> > > > > > the proposal and to move the rejected options to its own >> section. >> > And >> > > > > then >> > > > > > start a vote! >> > > > > > >> > > > > > Ismael >> > > > > > >> > > > > > On Fri, Aug 17, 2018 at 4:00 PM Jason Gustafson < >> > [email protected]> >> > > > > > wrote: >> > > > > > >> > > > > > > Hi Dongjin, >> > > > > > > >> > > > > > > Yes, that's a good summary. For clients which support v2, the >> > > client >> > > > > can >> > > > > > > parse the message format and hopefully raise a useful error >> > message >> > > > > > > indicating the unsupported compression type. For older >> clients, >> > our >> > > > > > options >> > > > > > > are probably (1) to down-convert to the old format using no >> > > > compression >> > > > > > > type, or (2) to return an error code. I'm leaning toward the >> > latter >> > > > as >> > > > > > the >> > > > > > > simpler solution, but the challenge is finding a good error >> code. >> > > Two >> > > > > > > possibilities might be INVALID_REQUEST or CORRUPT_MESSAGE. The >> > > > downside >> > > > > > is >> > > > > > > that old clients probably won't get a helpful message. >> However, >> > at >> > > > > least >> > > > > > > the behavior will be consistent in the sense that all clients >> > will >> > > > fail >> > > > > > if >> > > > > > > they do not support zstandard. >> > > > > > > >> > > > > > > What do you think? >> > > > > > > >> > > > > > > Thanks, >> > > > > > > Jason >> > > > > > > >> > > > > > > On Fri, Aug 17, 2018 at 8:08 AM, Dongjin Lee < >> [email protected] >> > > >> > > > > wrote: >> > > > > > > >> > > > > > > > Thanks Jason, I reviewed the down-converting logic following >> > your >> > > > > > > > explanation.[^1] You mean the following routines, right? >> > > > > > > > >> > > > > > > > - >> > > > > > > > https://github.com/apache/kafka/blob/trunk/core/src/ >> > > > > > > > main/scala/kafka/server/KafkaApis.scala#L534 >> > > > > > > > - >> > > > > > > > https://github.com/apache/kafka/blob/trunk/clients/src/ >> > > > > > > > main/java/org/apache/kafka/common/record/ >> > > LazyDownConversionRecords. >> > > > > > > > java#L165 >> > > > > > > > - >> > > > > > > > https://github.com/apache/kafka/blob/trunk/clients/src/ >> > > > > > > > >> main/java/org/apache/kafka/common/record/RecordsUtil.java#L40 >> > > > > > > > >> > > > > > > > It seems like your stance is like following: >> > > > > > > > >> > > > > > > > 1. In principle, Kafka does not change the compression codec >> > when >> > > > > > > > down-converting, since it requires inspecting the fetched >> data, >> > > > which >> > > > > > is >> > > > > > > > expensive. >> > > > > > > > 2. However, there are some cases the fetched data is >> inspected >> > > > > anyway. >> > > > > > In >> > > > > > > > this case, we can provide compression conversion from >> Zstandard >> > > to >> > > > > > > > classical ones[^2]. >> > > > > > > > >> > > > > > > > And from what I understand, the cases where the client >> without >> > > > > > ZStandard >> > > > > > > > support receives ZStandard compressed records can be >> organized >> > > into >> > > > > two >> > > > > > > > cases: >> > > > > > > > >> > > > > > > > a. The 'compression.type' configuration of given topic is >> > > > 'producer' >> > > > > > and >> > > > > > > > the producer compressed the records with ZStandard. (that >> is, >> > > using >> > > > > > > > ZStandard implicitly.) >> > > > > > > > b. The 'compression.type' configuration of given topic is >> > > 'zstd'; >> > > > > that >> > > > > > > is, >> > > > > > > > using ZStandard explicitly. >> > > > > > > > >> > > > > > > > As you stated, we don't have to handle the case b specially. >> > So, >> > > It >> > > > > > seems >> > > > > > > > like we can narrow the focus of the problem by joining case >> 1 >> > and >> > > > > case >> > > > > > b >> > > > > > > > like the following: >> > > > > > > > >> > > > > > > > > Given the topic with 'producer' as its 'compression.type' >> > > > > > > configuration, >> > > > > > > > ZStandard compressed records and old client without >> ZStandard, >> > is >> > > > > there >> > > > > > > any >> > > > > > > > case we need to inspect the records and can change the >> > > compression >> > > > > > type? >> > > > > > > If >> > > > > > > > so, can we provide compression type converting? >> > > > > > > > >> > > > > > > > Do I understand correctly? >> > > > > > > > >> > > > > > > > Best, >> > > > > > > > Dongjin >> > > > > > > > >> > > > > > > > [^1]: I'm sorry, I found that I was a little bit >> > misunderstanding >> > > > how >> > > > > > API >> > > > > > > > version works, after reviewing the downconvert logic & the >> > > protocol >> > > > > > > > documentation <https://kafka.apache.org/protocol>. >> > > > > > > > [^2]: None, Gzip, Snappy, Lz4. >> > > > > > > > >> > > > > > > > On Tue, Aug 14, 2018 at 2:16 AM Jason Gustafson < >> > > > [email protected]> >> > > > > > > > wrote: >> > > > > > > > >> > > > > > > > > > >> > > > > > > > > > But in my opinion, since the client will fail with the >> API >> > > > > version, >> > > > > > > so >> > > > > > > > we >> > > > > > > > > > don't need to down-convert the messages anyway. Isn't >> it? >> > > So, I >> > > > > > think >> > > > > > > > we >> > > > > > > > > > don't care about this case. (I'm sorry, I am not >> familiar >> > > with >> > > > > > > > > down-convert >> > > > > > > > > > logic.) >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > Currently the broker down-converts automatically when it >> > > receives >> > > > > an >> > > > > > > old >> > > > > > > > > version of the fetch request (a version which is known to >> > > predate >> > > > > the >> > > > > > > > > message format in use). Typically when down-converting the >> > > > message >> > > > > > > > format, >> > > > > > > > > we use the same compression type, but there is not much >> point >> > > in >> > > > > > doing >> > > > > > > so >> > > > > > > > > when we know the client doesn't support it. So if >> zstandard >> > is >> > > in >> > > > > > use, >> > > > > > > > and >> > > > > > > > > we have to down-convert anyway, then we can choose to use >> a >> > > > > different >> > > > > > > > > compression type or no compression type. >> > > > > > > > > >> > > > > > > > > From my perspective, there is no significant downside to >> > > bumping >> > > > > the >> > > > > > > > > protocol version and it has several potential benefits. >> > Version >> > > > > bumps >> > > > > > > are >> > > > > > > > > cheap. The main question mark in my mind is about >> > > > down-conversion. >> > > > > > > > Figuring >> > > > > > > > > out whether down-conversion is needed is hard generally >> > without >> > > > > > > > inspecting >> > > > > > > > > the fetched data, which is expensive. I think we agree in >> > > > principle >> > > > > > > that >> > > > > > > > we >> > > > > > > > > do not want to have to pay this cost generally and prefer >> the >> > > > > clients >> > > > > > > to >> > > > > > > > > fail when they see an unhandled compression type. The >> point I >> > > was >> > > > > > > making >> > > > > > > > is >> > > > > > > > > that there are some cases where we are either inspecting >> the >> > > data >> > > > > > > anyway >> > > > > > > > > (because we have to down-convert the message format), or >> we >> > > have >> > > > an >> > > > > > > easy >> > > > > > > > > way to tell whether zstandard is in use (the topic has it >> > > > > configured >> > > > > > > > > explicitly). In the latter case, we don't have to handle >> it >> > > > > > specially. >> > > > > > > > But >> > > > > > > > > we do have to decide how we will handle down-conversion to >> > > older >> > > > > > > formats. >> > > > > > > > > >> > > > > > > > > -Jason >> > > > > > > > > >> > > > > > > > > On Sun, Aug 12, 2018 at 5:15 PM, Dongjin Lee < >> > > [email protected] >> > > > > >> > > > > > > wrote: >> > > > > > > > > >> > > > > > > > > > Colin and Jason, >> > > > > > > > > > >> > > > > > > > > > Thanks for your opinions. In summarizing, the Pros and >> Cons >> > > of >> > > > > > > bumping >> > > > > > > > > > fetch API version are: >> > > > > > > > > > >> > > > > > > > > > Cons: >> > > > > > > > > > >> > > > > > > > > > - The Broker can't know whether a given message batch is >> > > > > compressed >> > > > > > > > with >> > > > > > > > > > zstd or not. >> > > > > > > > > > - Need some additional logic for the topic explicitly >> > > > configured >> > > > > to >> > > > > > > use >> > > > > > > > > > zstd. >> > > > > > > > > > >> > > > > > > > > > Pros: >> > > > > > > > > > >> > > > > > > > > > - The broker doesn't need to conduct expensive >> > > down-conversion. >> > > > > > > > > > - Can message the users to update their client. >> > > > > > > > > > >> > > > > > > > > > So, opinions for the backward-compatibility policy by >> far: >> > > > > > > > > > >> > > > > > > > > > - A: bump the API version - +2 (Colin, Jason) >> > > > > > > > > > - B: leave unchanged - +1 (Viktor) >> > > > > > > > > > >> > > > > > > > > > Here are my additional comments: >> > > > > > > > > > >> > > > > > > > > > @Colin >> > > > > > > > > > >> > > > > > > > > > I greatly appreciate your response. In the case of the >> > > > dictionary >> > > > > > > > > support, >> > > > > > > > > > of course, this issue should be addressed later so we >> don't >> > > > need >> > > > > it >> > > > > > > in >> > > > > > > > > the >> > > > > > > > > > first version. You are right - it is not late to try it >> > after >> > > > > some >> > > > > > > > > > benchmarks. What I mean is, we should keep in mind on >> that >> > > > > > potential >> > > > > > > > > > feature. >> > > > > > > > > > >> > > > > > > > > > @Jason >> > > > > > > > > > >> > > > > > > > > > You wrote, >> > > > > > > > > > >> > > > > > > > > > > Similarly, if we have to down-convert anyway because >> the >> > > > client >> > > > > > > does >> > > > > > > > > not >> > > > > > > > > > understand the message format, then we could also use a >> > > > different >> > > > > > > > > > compression type. >> > > > > > > > > > >> > > > > > > > > > But in my opinion, since the client will fail with the >> API >> > > > > version, >> > > > > > > so >> > > > > > > > we >> > > > > > > > > > don't need to down-convert the messages anyway. Isn't >> it? >> > > So, I >> > > > > > think >> > > > > > > > we >> > > > > > > > > > don't care about this case. (I'm sorry, I am not >> familiar >> > > with >> > > > > > > > > down-convert >> > > > > > > > > > logic.) >> > > > > > > > > > >> > > > > > > > > > Please give more opinions. Thanks! >> > > > > > > > > > >> > > > > > > > > > - Dongjin >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > On Wed, Aug 8, 2018 at 6:41 AM Jason Gustafson < >> > > > > [email protected] >> > > > > > > >> > > > > > > > > wrote: >> > > > > > > > > > >> > > > > > > > > > > Hey Colin, >> > > > > > > > > > > >> > > > > > > > > > > The problem for the fetch API is that the broker does >> not >> > > > > > generally >> > > > > > > > > know >> > > > > > > > > > if >> > > > > > > > > > > a batch was compressed with zstd unless it parses it. >> I >> > > think >> > > > > the >> > > > > > > > goal >> > > > > > > > > > here >> > > > > > > > > > > is to avoid the expensive down-conversion that is >> needed >> > to >> > > > > > ensure >> > > > > > > > > > > compatibility because it is only necessary if zstd is >> > > > actually >> > > > > in >> > > > > > > > use. >> > > > > > > > > > But >> > > > > > > > > > > as long as old clients can parse the message format, >> they >> > > > > should >> > > > > > > get >> > > > > > > > a >> > > > > > > > > > > reasonable error if they see an unsupported >> compression >> > > type >> > > > in >> > > > > > the >> > > > > > > > > > > attributes. Basically the onus is on users to ensure >> that >> > > > their >> > > > > > > > > consumers >> > > > > > > > > > > have been updated prior to using zstd. It seems like a >> > > > > reasonable >> > > > > > > > > > tradeoff >> > > > > > > > > > > to me. There are a couple cases that might be worth >> > > thinking >> > > > > > > through: >> > > > > > > > > > > >> > > > > > > > > > > 1. If a topic is explicitly configured to use zstd, >> then >> > we >> > > > > don't >> > > > > > > > need >> > > > > > > > > to >> > > > > > > > > > > check the fetched data for the compression type to >> know >> > if >> > > we >> > > > > > need >> > > > > > > > > > > down-conversion. If we did bump the Fetch API version, >> > then >> > > > we >> > > > > > > could >> > > > > > > > > > handle >> > > > > > > > > > > this case by either down-converting using a different >> > > > > compression >> > > > > > > > type >> > > > > > > > > or >> > > > > > > > > > > returning an error. >> > > > > > > > > > > 2. Similarly, if we have to down-convert anyway >> because >> > the >> > > > > > client >> > > > > > > > does >> > > > > > > > > > not >> > > > > > > > > > > understand the message format, then we could also use >> a >> > > > > different >> > > > > > > > > > > compression type. >> > > > > > > > > > > >> > > > > > > > > > > For the produce API, I think it's reasonable to bump >> the >> > > api >> > > > > > > version. >> > > > > > > > > > This >> > > > > > > > > > > can be used by clients to check whether a broker >> supports >> > > > zstd. >> > > > > > For >> > > > > > > > > > > example, we might support a list of preferred >> compression >> > > > types >> > > > > > in >> > > > > > > > the >> > > > > > > > > > > producer and we could use the broker to detect which >> > > version >> > > > to >> > > > > > > use. >> > > > > > > > > > > >> > > > > > > > > > > -Jason >> > > > > > > > > > > >> > > > > > > > > > > On Tue, Aug 7, 2018 at 1:32 PM, Colin McCabe < >> > > > > [email protected] >> > > > > > > >> > > > > > > > > wrote: >> > > > > > > > > > > >> > > > > > > > > > > > Thanks for bumping this, Dongjin. ZStd is a good >> > > > compression >> > > > > > > codec >> > > > > > > > > > and I >> > > > > > > > > > > > hope we can get this support in soon! >> > > > > > > > > > > > >> > > > > > > > > > > > I would say we can just bump the API version to >> > indicate >> > > > that >> > > > > > > ZStd >> > > > > > > > > > > support >> > > > > > > > > > > > is expected in new clients. We probably need some >> way >> > of >> > > > > > > > indicating >> > > > > > > > > to >> > > > > > > > > > > the >> > > > > > > > > > > > older clients that they can't consume the >> partitions, >> > as >> > > > > well. >> > > > > > > > > Perhaps >> > > > > > > > > > > we >> > > > > > > > > > > > can use the UNSUPPORTED_FOR_MESSAGE_FORMAT error? >> > > > > > > > > > > > >> > > > > > > > > > > > The license thing seems straightforward -- it's >> just a >> > > > matter >> > > > > > of >> > > > > > > > > adding >> > > > > > > > > > > > the text to the right files as per ASF guidelines. >> > > > > > > > > > > > >> > > > > > > > > > > > With regard to the dictionary support, do we really >> > need >> > > > that >> > > > > > in >> > > > > > > > the >> > > > > > > > > > > first >> > > > > > > > > > > > version? Hopefully message batches are big enough >> that >> > > > this >> > > > > > > isn't >> > > > > > > > > > > needed. >> > > > > > > > > > > > Some benchmarks might help here. >> > > > > > > > > > > > >> > > > > > > > > > > > best, >> > > > > > > > > > > > Colin >> > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > > On Tue, Aug 7, 2018, at 08:02, Dongjin Lee wrote: >> > > > > > > > > > > > > As Kafka 2.0.0 was released, let's reboot this >> issue, >> > > > > KIP-110 >> > > > > > > > > > > > > <https://cwiki.apache.org/ >> > > confluence/display/KAFKA/KIP- >> > > > > > > > > > > > 110%3A+Add+Codec+for+ZStandard+Compression> >> > > > > > > > > > > > > . >> > > > > > > > > > > > > >> > > > > > > > > > > > > For newcomers, Here is some summary of the >> history: >> > > > KIP-110 >> > > > > > was >> > > > > > > > > > > > originally >> > > > > > > > > > > > > worked for the issue KAFKA-4514 but, it lacked >> > > benchmark >> > > > > > > results >> > > > > > > > to >> > > > > > > > > > get >> > > > > > > > > > > > the >> > > > > > > > > > > > > agreement of the community. Later, Ivan Babrou and >> > some >> > > > > other >> > > > > > > > users >> > > > > > > > > > who >> > > > > > > > > > > > > adopted the patch provided their excellent >> > performance >> > > > > report >> > > > > > > > which >> > > > > > > > > > is >> > > > > > > > > > > > now >> > > > > > > > > > > > > included in the KIP, but it postponed again >> because >> > of >> > > > the >> > > > > > > > > community >> > > > > > > > > > > was >> > > > > > > > > > > > > busy for 2.0.0 release. It is why I now reboot >> this >> > > > issue. >> > > > > > > > > > > > > >> > > > > > > > > > > > > The following is the current status of the >> feature: >> > You >> > > > can >> > > > > > > check >> > > > > > > > > the >> > > > > > > > > > > > > current draft implementation here >> > > > > > > > > > > > > <https://github.com/apache/kafka/pull/2267>. It >> is >> > > based >> > > > > on >> > > > > > > zstd >> > > > > > > > > > 1.3.5 >> > > > > > > > > > > > and >> > > > > > > > > > > > > periodically rebased onto the latest trunk[^1]. >> > > > > > > > > > > > > >> > > > > > > > > > > > > The issues that should be addressed is like >> > following: >> > > > > > > > > > > > > >> > > > > > > > > > > > > *1. Backward Compatibility* >> > > > > > > > > > > > > >> > > > > > > > > > > > > To support old consumers, we need to take a >> strategy >> > to >> > > > > > handle >> > > > > > > > the >> > > > > > > > > > old >> > > > > > > > > > > > > consumers. Current candidates are: >> > > > > > > > > > > > > >> > > > > > > > > > > > > - Bump API version >> > > > > > > > > > > > > - Leave unchanged: let the old clients fail. >> > > > > > > > > > > > > - Improve the error messages: >> > > > > > > > > > > > > >> > > > > > > > > > > > > *2. Dictionary Support* >> > > > > > > > > > > > > >> > > > > > > > > > > > > To support zstd's dictionary feature in the future >> > (if >> > > > > > needed), >> > > > > > > > we >> > > > > > > > > > need >> > > > > > > > > > > > to >> > > > > > > > > > > > > sketch how it should be and leave some room for >> it. >> > As >> > > of >> > > > > > now, >> > > > > > > > > there >> > > > > > > > > > > has >> > > > > > > > > > > > > been no discussion on this topic yet. >> > > > > > > > > > > > > >> > > > > > > > > > > > > *3. License* >> > > > > > > > > > > > > >> > > > > > > > > > > > > To use this feature, we need to add license of >> zstd >> > and >> > > > > > > zstd-jni >> > > > > > > > to >> > > > > > > > > > the >> > > > > > > > > > > > > project. (Thanks to Viktor Somogyi for raising >> this >> > > > issue!) >> > > > > > It >> > > > > > > > > seems >> > > > > > > > > > > like >> > > > > > > > > > > > > what Apache Spark did would be a good example but >> > there >> > > > has >> > > > > > > been >> > > > > > > > no >> > > > > > > > > > > > > discussion yet. >> > > > > > > > > > > > > >> > > > > > > > > > > > > You can find the details of the above issues in >> the >> > KIP >> > > > > > > document. >> > > > > > > > > > > Please >> > > > > > > > > > > > > have a look when you are free, and give me >> feedback. >> > > All >> > > > > > kinds >> > > > > > > of >> > > > > > > > > > > > > participating are welcome. >> > > > > > > > > > > > > >> > > > > > > > > > > > > Best, >> > > > > > > > > > > > > Dongjin >> > > > > > > > > > > > > >> > > > > > > > > > > > > [^1]: At the time of writing, commit 6b4fb8152. >> > > > > > > > > > > > > >> > > > > > > > > > > > > On Sat, Jul 14, 2018 at 10:45 PM Dongjin Lee < >> > > > > > > [email protected] >> > > > > > > > > >> > > > > > > > > > > wrote: >> > > > > > > > > > > > > >> > > > > > > > > > > > > > Sorry for the late reply. >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > In short, I could not submit the updated KIP by >> the >> > > > > feature >> > > > > > > > > freeze >> > > > > > > > > > > > > > deadline of 2.0.0. For this reason, it will not >> be >> > > > > included >> > > > > > > in >> > > > > > > > > the >> > > > > > > > > > > > 2.0.0 >> > > > > > > > > > > > > > release and all discussion for this issue were >> > > > postponed >> > > > > > > after >> > > > > > > > > the >> > > > > > > > > > > > release >> > > > > > > > > > > > > > of 2.0.0. >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > I have been updating the PR following recent >> > updates. >> > > > > Just >> > > > > > > > now, I >> > > > > > > > > > > > rebased >> > > > > > > > > > > > > > it against the latest trunk and updated the zstd >> > > > version >> > > > > > into >> > > > > > > > > > 1.3.5. >> > > > > > > > > > > > If you >> > > > > > > > > > > > > > need some request, don't hesitate to notify me. >> > (But >> > > > not >> > > > > > this >> > > > > > > > > > thread >> > > > > > > > > > > - >> > > > > > > > > > > > just >> > > > > > > > > > > > > > send me the message directly.) >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > Best, >> > > > > > > > > > > > > > Dongjin >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > On Tue, Jul 10, 2018 at 11:57 PM Bobby Evans < >> > > > > > > [email protected] >> > > > > > > > > >> > > > > > > > > > > wrote: >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> I there any update on this. The performance >> > > > > improvements >> > > > > > > are >> > > > > > > > > > quite >> > > > > > > > > > > > > >> impressive and I really would like to stop >> forking >> > > > kafka >> > > > > > > just >> > > > > > > > to >> > > > > > > > > > get >> > > > > > > > > > > > this >> > > > > > > > > > > > > >> in. >> > > > > > > > > > > > > >> >> > > > > > > > > > > > > >> Thanks, >> > > > > > > > > > > > > >> >> > > > > > > > > > > > > >> Bobby >> > > > > > > > > > > > > >> >> > > > > > > > > > > > > >> On Wed, Jun 13, 2018 at 8:56 PM Dongjin Lee < >> > > > > > > > [email protected] >> > > > > > > > > > >> > > > > > > > > > > > wrote: >> > > > > > > > > > > > > >> >> > > > > > > > > > > > > >> > Ismael, >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> > Oh, I forgot all of you are on working frenzy >> > for >> > > > 2.0! >> > > > > > No >> > > > > > > > > > problem, >> > > > > > > > > > > > take >> > > > > > > > > > > > > >> > your time. I am also working at another issue >> > now. >> > > > > Thank >> > > > > > > you >> > > > > > > > > for >> > > > > > > > > > > > > >> letting me >> > > > > > > > > > > > > >> > know. >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> > Best, >> > > > > > > > > > > > > >> > Dongjin >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> > On Wed, Jun 13, 2018, 11:44 PM Ismael Juma < >> > > > > > > > [email protected] >> > > > > > > > > > >> > > > > > > > > > > > wrote: >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> > > Sorry for the delay Dongjin. Everyone is >> busy >> > > > > > finalising >> > > > > > > > > > 2.0.0. >> > > > > > > > > > > > This >> > > > > > > > > > > > > >> KIP >> > > > > > > > > > > > > >> > > seems like a great candidate for 2.1.0 and >> > > > hopefully >> > > > > > > there >> > > > > > > > > > will >> > > > > > > > > > > be >> > > > > > > > > > > > > >> more >> > > > > > > > > > > > > >> > of >> > > > > > > > > > > > > >> > > a discussion next week. :) >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > > Ismael >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > > On Wed, 13 Jun 2018, 05:17 Dongjin Lee, < >> > > > > > > > [email protected] >> > > > > > > > > > >> > > > > > > > > > > > wrote: >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > > > Hello. I just updated my draft >> > implementation: >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > 1. Rebased to latest trunk (commit >> 5145d6b) >> > > > > > > > > > > > > >> > > > 2. Apply ZStd 1.3.4 >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > You can check out the implementation from >> > here >> > > > > > > > > > > > > >> > > > < >> https://github.com/apache/kafka/pull/2267 >> > >. >> > > If >> > > > > you >> > > > > > > > > > > experience >> > > > > > > > > > > > any >> > > > > > > > > > > > > >> > > problem >> > > > > > > > > > > > > >> > > > running it, don't hesitate to give me a >> > > mention. >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > Best, >> > > > > > > > > > > > > >> > > > Dongjin >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > On Tue, Jun 12, 2018 at 6:50 PM Dongjin >> Lee >> > < >> > > > > > > > > > > [email protected] >> > > > > > > > > > > > > >> > > > > > > > > > > > > >> > wrote: >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > > Here is the short conclusion about the >> > > license >> > > > > > > > problem: >> > > > > > > > > > *We >> > > > > > > > > > > > can >> > > > > > > > > > > > > >> use >> > > > > > > > > > > > > >> > > zstd >> > > > > > > > > > > > > >> > > > > and zstd-jni without any problem, but >> we >> > > need >> > > > to >> > > > > > > > include >> > > > > > > > > > > their >> > > > > > > > > > > > > >> > license, >> > > > > > > > > > > > > >> > > > > e.g., BSD license.* >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > Both of BSD 2 Clause License & 3 Clause >> > > > License >> > > > > > > > requires >> > > > > > > > > > to >> > > > > > > > > > > > > >> include >> > > > > > > > > > > > > >> > the >> > > > > > > > > > > > > >> > > > > license used, and BSD 3 Clause License >> > > > requires >> > > > > > that >> > > > > > > > the >> > > > > > > > > > > name >> > > > > > > > > > > > of >> > > > > > > > > > > > > >> the >> > > > > > > > > > > > > >> > > > > contributor can't be used to endorse or >> > > > promote >> > > > > > the >> > > > > > > > > > product. >> > > > > > > > > > > > > >> That's >> > > > > > > > > > > > > >> > it >> > > > > > > > > > > > > >> > > > > < >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> >> > http://www.mikestratton.net/2011/12/is-bsd-license- >> > > > > > > > > > > > compatible-with-apache-2-0-license/ >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > - They are not listed in the list of >> > > > prohibited >> > > > > > > > licenses >> > > > > > > > > > > > > >> > > > > <https://www.apache.org/legal/ >> > > > > > > > resolved.html#category-x> >> > > > > > > > > > > also. >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > Here is how Spark did for it >> > > > > > > > > > > > > >> > > > > <https://issues.apache.org/ >> > > > > > jira/browse/SPARK-19112 >> > > > > > > >: >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > - They made a directory dedicated to >> the >> > > > > > dependency >> > > > > > > > > > license >> > > > > > > > > > > > files >> > > > > > > > > > > > > >> > > > > < >> > > > > > > https://github.com/apache/spark/tree/master/licenses >> > > > > > > > > >> > > > > > > > > > and >> > > > > > > > > > > > added >> > > > > > > > > > > > > >> > > > licenses >> > > > > > > > > > > > > >> > > > > for Zstd >> > > > > > > > > > > > > >> > > > > < >> > > > > > > > > > > > > >> > >> > > > https://github.com/apache/spark/blob/master/licenses/ >> > > > > > > > > > > > LICENSE-zstd.txt >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > > & >> > > > > > > > > > > > > >> > > > > Zstd-jni >> > > > > > > > > > > > > >> > > > > < >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> https://github.com/apache/ >> > > spark/blob/master/licenses/ >> > > > > > > > > > > > LICENSE-zstd-jni.txt >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> > > > > . >> > > > > > > > > > > > > >> > > > > - Added a link to the original license >> > files >> > > > in >> > > > > > > > LICENSE. >> > > > > > > > > > > > > >> > > > > < >> > > > > https://github.com/apache/spark/pull/18805/files >> > > > > > > >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > If needed, I can make a similar update. >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > Thanks for pointing out this problem, >> > > Viktor! >> > > > > Nice >> > > > > > > > > catch! >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > Best, >> > > > > > > > > > > > > >> > > > > Dongjin >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > > On Mon, Jun 11, 2018 at 11:50 PM >> Dongjin >> > > Lee < >> > > > > > > > > > > > [email protected]> >> > > > > > > > > > > > > >> > > wrote: >> > > > > > > > > > > > > >> > > > > >> > > > > > > > > > > > > >> > > > >> I greatly appreciate your >> comprehensive >> > > > > > reasoning. >> > > > > > > > so: >> > > > > > > > > +1 >> > > > > > > > > > > > for b >> > > > > > > > > > > > > >> > until >> > > > > > > > > > > > > >> > > > now. >> > > > > > > > > > > > > >> > > > >> >> > > > > > > > > > > > > >> > > > >> For the license issues, I will have a >> > check >> > > > on >> > > > > > how >> > > > > > > > the >> > > > > > > > > > over >> > > > > > > > > > > > > >> projects >> > > > > > > > > > > > > >> > > are >> > > > > > > > > > > > > >> > > > >> doing and share the results. >> > > > > > > > > > > > > >> > > > >> >> > > > > > > > > > > > > >> > > > >> Best, >> > > > > > > > > > > > > >> > > > >> Dongjin >> > > > > > > > > > > > > >> > > > >> >> > > > > > > > > > > > > >> > > > >> On Mon, Jun 11, 2018 at 10:08 PM >> Viktor >> > > > > Somogyi < >> > > > > > > > > > > > > >> > > > [email protected]> >> > > > > > > > > > > > > >> > > > >> wrote: >> > > > > > > > > > > > > >> > > > >> >> > > > > > > > > > > > > >> > > > >>> Hi Dongjin, >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> A couple of comments: >> > > > > > > > > > > > > >> > > > >>> I would vote for option b. in the >> > > "backward >> > > > > > > > > > compatibility" >> > > > > > > > > > > > > >> section. >> > > > > > > > > > > > > >> > > My >> > > > > > > > > > > > > >> > > > >>> reasoning for this is that users >> > upgrading >> > > > to >> > > > > a >> > > > > > > zstd >> > > > > > > > > > > > compatible >> > > > > > > > > > > > > >> > > version >> > > > > > > > > > > > > >> > > > >>> won't start to use it automatically, >> so >> > > > manual >> > > > > > > > > > > > reconfiguration >> > > > > > > > > > > > > >> is >> > > > > > > > > > > > > >> > > > >>> required. >> > > > > > > > > > > > > >> > > > >>> Therefore an upgrade won't mess up >> the >> > > > > cluster. >> > > > > > If >> > > > > > > > not >> > > > > > > > > > all >> > > > > > > > > > > > the >> > > > > > > > > > > > > >> > > clients >> > > > > > > > > > > > > >> > > > >>> are >> > > > > > > > > > > > > >> > > > >>> upgraded but just some of them and >> > they'd >> > > > > start >> > > > > > to >> > > > > > > > use >> > > > > > > > > > > zstd >> > > > > > > > > > > > > >> then it >> > > > > > > > > > > > > >> > > > would >> > > > > > > > > > > > > >> > > > >>> cause errors in the cluster. I'd >> like to >> > > > > presume >> > > > > > > > > though >> > > > > > > > > > > that >> > > > > > > > > > > > > >> this >> > > > > > > > > > > > > >> > is >> > > > > > > > > > > > > >> > > a >> > > > > > > > > > > > > >> > > > >>> very >> > > > > > > > > > > > > >> > > > >>> obvious failure case and nobody >> should >> > be >> > > > > > > surprised >> > > > > > > > if >> > > > > > > > > > it >> > > > > > > > > > > > didn't >> > > > > > > > > > > > > >> > > work. >> > > > > > > > > > > > > >> > > > >>> I wouldn't choose a. as I think we >> > should >> > > > bump >> > > > > > the >> > > > > > > > > fetch >> > > > > > > > > > > and >> > > > > > > > > > > > > >> > produce >> > > > > > > > > > > > > >> > > > >>> requests if it's a change in the >> message >> > > > > format. >> > > > > > > > > > Moreover >> > > > > > > > > > > if >> > > > > > > > > > > > > >> some >> > > > > > > > > > > > > >> > of >> > > > > > > > > > > > > >> > > > the >> > > > > > > > > > > > > >> > > > >>> producers and the brokers are >> upgraded >> > but >> > > > > some >> > > > > > of >> > > > > > > > the >> > > > > > > > > > > > consumers >> > > > > > > > > > > > > >> > are >> > > > > > > > > > > > > >> > > > not, >> > > > > > > > > > > > > >> > > > >>> then we wouldn't prevent the error >> when >> > > the >> > > > > old >> > > > > > > > > consumer >> > > > > > > > > > > > tries >> > > > > > > > > > > > > >> to >> > > > > > > > > > > > > >> > > > consume >> > > > > > > > > > > > > >> > > > >>> the zstd compressed messages. >> > > > > > > > > > > > > >> > > > >>> I wouldn't choose c. either as I >> think >> > > > binding >> > > > > > the >> > > > > > > > > > > > compression >> > > > > > > > > > > > > >> type >> > > > > > > > > > > > > >> > > to >> > > > > > > > > > > > > >> > > > an >> > > > > > > > > > > > > >> > > > >>> API is not so obvious from the >> > developer's >> > > > > > > > > perspective. >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> I would also prefer to use the >> existing >> > > > > binding, >> > > > > > > > > however >> > > > > > > > > > > we >> > > > > > > > > > > > must >> > > > > > > > > > > > > >> > > > respect >> > > > > > > > > > > > > >> > > > >>> the licenses: >> > > > > > > > > > > > > >> > > > >>> "The code for these JNI bindings is >> > > licenced >> > > > > > under >> > > > > > > > > > > 2-clause >> > > > > > > > > > > > BSD >> > > > > > > > > > > > > >> > > > license. >> > > > > > > > > > > > > >> > > > >>> The native Zstd library is licensed >> > under >> > > > > > 3-clause >> > > > > > > > BSD >> > > > > > > > > > > > license >> > > > > > > > > > > > > >> and >> > > > > > > > > > > > > >> > > > GPL2" >> > > > > > > > > > > > > >> > > > >>> Based on the FAQ page >> > > > > > > > > > > > > >> > > > >>> https://www.apache.org/legal/ >> > > > > > > > resolved.html#category-a >> > > > > > > > > > > > > >> > > > >>> we may use 2- and 3-clause BSD >> licenses >> > > but >> > > > > the >> > > > > > > > Apache >> > > > > > > > > > > > license >> > > > > > > > > > > > > >> is >> > > > > > > > > > > > > >> > not >> > > > > > > > > > > > > >> > > > >>> compatible with GPL2. I'm hoping that >> > the >> > > > > > > "3-clause >> > > > > > > > > BSD >> > > > > > > > > > > > license >> > > > > > > > > > > > > >> and >> > > > > > > > > > > > > >> > > > GPL2" >> > > > > > > > > > > > > >> > > > >>> is really not an AND but an OR in >> this >> > > case, >> > > > > but >> > > > > > > I'm >> > > > > > > > > no >> > > > > > > > > > > > lawyer, >> > > > > > > > > > > > > >> > just >> > > > > > > > > > > > > >> > > > >>> wanted >> > > > > > > > > > > > > >> > > > >>> to make the point that we should >> watch >> > out >> > > > for >> > > > > > > > > licenses. >> > > > > > > > > > > :) >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> Regards, >> > > > > > > > > > > > > >> > > > >>> Viktor >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> On Sun, Jun 10, 2018 at 3:02 AM Ivan >> > > Babrou >> > > > < >> > > > > > > > > > > > [email protected]> >> > > > > > > > > > > > > >> > > wrote: >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >>> > Hello, >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> > This is Ivan and I still very much >> > > support >> > > > > the >> > > > > > > > fact >> > > > > > > > > > that >> > > > > > > > > > > > zstd >> > > > > > > > > > > > > >> > > > >>> compression >> > > > > > > > > > > > > >> > > > >>> > should be included out of the box. >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> > Please think about the environment, >> > you >> > > > can >> > > > > > save >> > > > > > > > > > quite a >> > > > > > > > > > > > lot >> > > > > > > > > > > > > >> of >> > > > > > > > > > > > > >> > > > >>> hardware >> > > > > > > > > > > > > >> > > > >>> > with it. >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> > Thank you. >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> > On Sat, Jun 9, 2018 at 14:14 >> Dongjin >> > > Lee < >> > > > > > > > > > > > [email protected]> >> > > > > > > > > > > > > >> > > wrote: >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> > > Since there are no responses for >> a >> > > > week, I >> > > > > > > > decided >> > > > > > > > > > to >> > > > > > > > > > > > > >> > reinitiate >> > > > > > > > > > > > > >> > > > the >> > > > > > > > > > > > > >> > > > >>> > > discussion thread. >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > >> > > > > > > > > > > > > >> > > > >>> >> > > > > > > > > > > > > >> > > > >> > > > > > > > > > > > > >> > > >> > > > > > > > > > > > > >> > >> > > > > > > > > > > > > >> >> > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP- >> > > > > > > > > > > > 110%3A+Add+Codec+for+ZStandard+Compression >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > > This KIP is about to introduce >> > > ZStandard >> > > > > > > > > Compression >> > > > > > > > > > > > into >> > > > > > > > > > > > > >> > Apache >> > > > > > > > > > > > > >> > > > >>> Kafka. >> > > > > > > > > > > > > >> > > > >>> > > The reason why it is posted again >> > has >> > > a >> > > > > > story: >> > > > > > > > It >> > > > > > > > > > was >> > > > > > > > > > > > > >> > originally >> > > > > > > > > > > > > >> > > > >>> posted >> > > > > > > > > > > > > >> > > > >>> > to >> > > > > > > > > > > > > >> > > > >>> > > the dev mailing list more than >> one >> > > year >> > > > > ago >> > > > > > > but >> > > > > > > > > > since >> > > > > > > > > > > it >> > > > > > > > > > > > > >> has no >> > > > > > > > > > > > > >> > > > >>> > performance >> > > > > > > > > > > > > >> > > > >>> > > report included, it was postponed >> > > later. >> > > > > But >> > > > > > > > Some >> > > > > > > > > > > people >> > > > > > > > > > > > > >> > > (including >> > > > > > > > > > > > > >> > > > >>> Ivan) >> > > > > > > > > > > > > >> > > > >>> > > reported excellent performance >> > report >> > > > with >> > > > > > the >> > > > > > > > > draft >> > > > > > > > > > > PR, >> > > > > > > > > > > > > >> this >> > > > > > > > > > > > > >> > > work >> > > > > > > > > > > > > >> > > > >>> is now >> > > > > > > > > > > > > >> > > > >>> > > reactivated. >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > > The updated KIP document includes >> > some >> > > > > > > expected >> > > > > > > > > > > > problems and >> > > > > > > > > > > > > >> > > their >> > > > > > > > > > > > > >> > > > >>> > > candidate alternatives. Please >> have >> > a >> > > > look >> > > > > > > when >> > > > > > > > > you >> > > > > > > > > > > are >> > > > > > > > > > > > > >> free, >> > > > > > > > > > > > > >> > and >> > > > > > > > > > > > > >> > > > >>> give >> > > > > > > > > > > > > >> > > > >>> > me a >> > > > > > > > > > > > > >> > > > >>> > > feedback. All kinds of >> participating >> > > are >> > > > > > > > welcome. >> > > > > > > > > > > > > >> > > > >>> > > >> > > > > > > > > > > > > >> > > > >>> > > 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 >> > > > > > > > > > > > > >> > > > >> <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 >> > > > > > > > > > > > > >> > > > > <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 >> > > > > > > > > > > > > >> > > > <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 >> > > > > > > > > > > > > >> <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 >> > > > > > > > > > > > > <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 >> > > > > > > > > > > <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 >> > > > > > > > > <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 >> > > > <http://github.com/dongji <http://github.com/dongjinleekr> > > -- *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>*
