[jira] [Created] (KAFKA-13375) Kafka streams apps w/EOS unable to start at InitProducerId

["Lerh Chuan Low (Jira)" <ji...@apache.org>]

Lerh Chuan Low created KAFKA-13375:
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             Summary: Kafka streams apps w/EOS unable to start at InitProducerId
                 Key: KAFKA-13375
                 URL: https://issues.apache.org/jira/browse/KAFKA-13375
             Project: Kafka
          Issue Type: Bug
          Components: core
    Affects Versions: 2.8.0
            Reporter: Lerh Chuan Low


Hello, I'm wondering if this is a Kafka bug. Our environment setup is as follows:

Kafka streams 2.8 - with *EXACTLY_ONCE* turned on (Not *EOS_BETA*, but I don't think the changes introduced in EOS beta should affect this)
Kafka broker 2.8. 

We have this situation where we were doing a rolling restart of the broker to apply some security changes. After we finished, 4 out of some 15 Stream Apps are unable to start. They can never succeed, no matter what we do. 

They fail with the error:


{code:java}
 2021-10-14 07:20:13,548 WARN [srn-rec-feeder-802c18a1-9512-4a2a-8c2e-00e37550199d-StreamThread-3] o.a.k.s.p.i.StreamsProducer stream-thread [srn-rec-feeder-802c18a1-9512-4a2a-8c2e-00e37550199d-StreamThread-3] task [0_6] Timeout exception caught trying to initialize transactions. The broker is either slow or in bad state (like not having enough replicas) in responding to the request, or the connection to broker was interrupted sending the request or receiving the response. Will retry initializing the task in the next loop. Consider overwriting max.block.ms to a larger value to avoid timeout errors{code}


We found a previous Jira describing the issue here: https://issues.apache.org/jira/browse/KAFKA-8803. It seems like back then what people did was to rolling restart the brokers. We tried that - we targeted the group coordinators for our failing apps, then transaction coordinators, then all of them. It hasn't resolved our issue so far. 

A few interesting things we've found so far:

- What I can see is that all the failing apps only fail on certain partitions. E.g for the app above, only partition 6 never succeeds. Partition 6 shares the same coordinator as some of the other partitions and those work, so it seems like the issue isn't related to broker state. 

- All the failing apps have a message similar to this 


{code:java}
[2021-10-14 00:54:51,569] INFO [Transaction Marker Request Completion Handler 103]: Sending srn-rec-feeder-0_6's transaction marker for partition srn-bot-003-14 has permanently failed with error org.apache.kafka.common.errors.InvalidProducerEpochException with the current coordinator epoch 143; cancel sending any more transaction markers TxnMarkerEntry{producerId=7001, producerEpoch=610, coordinatorEpoch=143, result=ABORT, partitions=[srn-bot-003-14]} to the brokers (kafka.coordinator.transaction.TransactionMarkerRequestCompletionHandler) {code}
While we were restarting the brokers. They all failed shortly after. No other consumer groups for the other working partitions/working stream apps logged this message. 

On digging around in git blame and reading through the source, it looks like this is meant to be benign. 

- We tried DEBUG logging for the TransactionCoordinator and TransactionStateManager. We can see (assigner is a functioning app)
{code:java}
[2021-10-14 06:48:23,813] DEBUG [TransactionCoordinator id=105] Returning CONCURRENT_TRANSACTIONS error code to client for srn-assigner-0_14's AddPartitions request (kafka.coordinator.transaction.TransactionCoordinator) {code}
I've seen those before during steady state. I do believe they are benign. We never see it for the problematic partitions/consumer groups for some reason.
- We tried turning on TRACE for KafkaApis. We can see
{code:java}
[2021-10-14 06:56:58,408] TRACE [KafkaApi-105] Completed srn-rec-feeder-0_6's InitProducerIdRequest with result InitProducerIdResult(-1,-1,CONCURRENT_TRANSACTIONS) from client srn-rec-feeder-802c18a1-9512-4a2a-8c2e-00e37550199d-StreamThread-4-0_6-producer. (kafka.server.KafkaApis) {code}
It starts to make me wonder if there's a situation where Kafka is unable to abort the transactions if there is never any success in initializing a producer ID. But this is diving deep into insider knowledge terriroty that I simply don't have. I'm wondering if anyone with more knowledge of how transactions work can shed some light here if we are in the wrong path, or if there's any way to restore operations at all short of a streams reset? From a cursory look at
{noformat}
TransactionCoordinator#handleInitProducerId {noformat}
it looks like any old transactions should just be aborted and life goes on, but it's not happening. 



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