Re: INVALID_FETCH_SESSION_EPOCH after upgrade to 1.1.0

[Mark Anderson <ma...@gmail.com>]

Also in this case will it fall back to a full request?

Hence no data is lost but it might increase latency?

Thanks
Mark

On Thu, 26 Jul 2018, 12:28 Mark Anderson, <ma...@gmail.com> wrote:

> Ted,
>
> Below are examples of the DEBUG entries from FetchSession
>
> [2018-07-26 11:14:43,461] DEBUG Created a new error FetchContext for
> session id 1139872548: expected epoch 13719, but got epoch 13718.
> (kafka.server.FetchManager)
> [2018-07-26 11:24:35,339] DEBUG Created a new error FetchContext for
> session id 738221153: expected epoch 12679, but got epoch 12678.
> (kafka.server.FetchManager)
>
> [2018-07-26 11:24:36,967] DEBUG Created a new error FetchContext for
> session id 1696245254: expected epoch 34143, but got epoch 34142.
> (kafka.server.FetchManager)
>
> [2018-07-26 11:24:47,736] DEBUG Created a new error FetchContext for
> session id 2131207151: expected epoch 14185, but got epoch 14184.
> (kafka.server.FetchManager)
> [2018-07-26 11:24:51,414] DEBUG Created a new error FetchContext for
> session id 1213530731: expected epoch 77250, but got epoch 77249.
> (kafka.server.FetchManager)
>
> Is the fact that there are always out by one significant?
>
> Thanks,
> Mark
>
> On Wed, 13 Jun 2018 at 17:46 Ted Yu <yu...@gmail.com> wrote:
>
>> You would need this (plus any appender you want the log to go to):
>>
>> log4j.logger.kafka.server=DEBUG
>>
>> FYI
>>
>> On Wed, Jun 13, 2018 at 9:15 AM, Ted Yu <yu...@gmail.com> wrote:
>>
>>> In log4j.properties, can you make the following change (you can keep
>>> whatever follows the first comma in the rootLogger line):
>>>
>>> log4j.rootLogger=DEBUG
>>> log4j.logger.org.apache.kafka=DEBUG
>>>
>>> FetchSession.scala is in kafka.server package. You can just turn on
>>> DEBUG for this package.
>>>
>>> FYI
>>>
>>>
>>> On Wed, Jun 13, 2018 at 9:08 AM, Mark Anderson <ma...@gmail.com>
>>> wrote:
>>>
>>>> Ted
>>>>
>>>> I don't see any other INFO log messages so I assume that means it is the
>>>> DEBUG case I'm seeing?
>>>>
>>>> I don't have DEBUG enabled at the moment.
>>>>
>>>> Thanks
>>>>
>>>> On Wed, 13 Jun 2018, 00:21 Ted Yu, <yu...@gmail.com> wrote:
>>>>
>>>> > Before Errors.INVALID_FETCH_SESSION_EPOCH is returned,
>>>> FetchSession.scala
>>>> > would log the reason for the response.
>>>> > There are 3 cases, 2 with info log and 1 with debug log.
>>>> > Here is one code snippet:
>>>> >
>>>> >             if (session.epoch != reqMetadata.epoch()) {
>>>> >
>>>> >               debug(s"Created a new error FetchContext for session id
>>>> ${
>>>> > session.id}: expected " +
>>>> >
>>>> >                 s"epoch ${session.epoch}, but got epoch $
>>>> > {reqMetadata.epoch()}.")
>>>> >
>>>> >               new
>>>> SessionErrorContext(Errors.INVALID_FETCH_SESSION_EPOCH,
>>>> > reqMetadata)
>>>> >
>>>> > Can you pastebin the log line preceding what you pasted ?
>>>> >
>>>> > Thanks
>>>> >
>>>> > On Tue, Jun 12, 2018 at 3:12 PM, Mark Anderson <manderson23@gmail.com
>>>> >
>>>> > wrote:
>>>> >
>>>> > > We recently updated our Kafka brokers and clients to 1.1.0. Since
>>>> the
>>>> > > upgrade we periodically see INFO log entries such as
>>>> > >
>>>> > > INFO Jun 08 08:30:20.335 61161458 [KafkaRecordConsumer-0]
>>>> > > org.apache.kafka.clients.FetchSessionHandler [Consumer
>>>> > > clientId=consumer-1,
>>>> > > groupId=group_60_10] Node 3 was unable to process the fetch request
>>>> with
>>>> > > (sessionId=819759315, epoch=145991): INVALID_FETCH_SESSION_EPOCH.
>>>> > >
>>>> > > I see that this message comes from the changes introduced in
>>>> KIP-227:
>>>> > > Introduce Incremental FetchRequests To Increase Partition Stability
>>>> > > <https://cwiki.apache.org/confluence/display/KAFKA/KIP-
>>>> > > 227%3A+Introduce+Incremental+FetchRequests+to+Increase+
>>>> > > Partition+Scalability>.
>>>> > > However, I cannot find any detailed information about why this
>>>> message
>>>> > > would appear or what parameters might have to be tuned after its
>>>> > > introduction.
>>>> > >
>>>> > > So far it doesn't seem to have an impact on consumer behaviour with
>>>> > respect
>>>> > > to receiving records but I would like to understand
>>>> > >
>>>> > >    1. Why is the message being logged?
>>>> > >    2. Do I need to do anything?
>>>> > >    3. Can anything be done to stop it being logged?
>>>> > >
>>>> > > Thanks,
>>>> > > Mark
>>>> > >
>>>> >
>>>>
>>>
>>>
>>