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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