Hi Nitty,
Sorry, I should have clarified. The reason I'm thinking about shutdown here
is that, when exactly-once support is enabled on a Kafka Connect cluster
and a new set of task configurations is generated for a connector, the
Connect framework makes an effort to shut down all the old task instances
for that connector, and then fences out the transactional producers for all
of those instances. I was thinking that this may lead to the producer
exceptions you are seeing but, after double-checking this assumption, that
does not appear to be the case.
Would it be possible to share the source code for your connector and a
reproduction scenario for what you're seeing? That may be easier than
coordinating a call.
Cheers,
Chris
On Tue, Mar 14, 2023 at 6:15 AM NITTY BENNY <nittybe...@gmail.com> wrote:
> Hi Chris,
>
> Is there any possibility to have a call with you? This is actually blocking
> our delivery, I actually want to sort with this.
>
> Thanks,
> Nitty
>
> On Mon, Mar 13, 2023 at 8:18 PM NITTY BENNY <nittybe...@gmail.com> wrote:
>
> > Hi Chris,
> >
> > I really don't understand why a graceful shutdown will happen during a
> > commit operation? Am I understanding something wrong here?. I see
> > this happens when I have a batch of 2 valid records and in the second
> > batch the record is invalid. In that case I want to commit the valid
> > records. So I called commit and sent an empty list for the current batch
> to
> > poll() and then when the next file comes in and poll sees new records, I
> > see InvalidProducerEpochException.
> > Please advise me.
> >
> > Thanks,
> > Nitty
> >
> > On Mon, Mar 13, 2023 at 5:33 PM NITTY BENNY <nittybe...@gmail.com>
> wrote:
> >
> >> Hi Chris,
> >>
> >> The difference is in the Task Classes, no difference for value/key
> >> convertors.
> >>
> >> I don’t see log messages for graceful shutdown. I am not clear on what
> >> you mean by shutting down the task.
> >>
> >> I called the commit operation for the successful records. Should I
> >> perform any other steps if I have an invalid record?
> >> Please advise.
> >>
> >> Thanks,
> >> Nitty
> >>
> >> On Mon, Mar 13, 2023 at 3:42 PM Chris Egerton <chr...@aiven.io.invalid>
> >> wrote:
> >>
> >>> Hi Nitty,
> >>>
> >>> Thanks again for all the details here, especially the log messages.
> >>>
> >>> > The below mentioned issue is happening for Json connector only. Is
> >>> there
> >>> any difference with asn1,binary,csv and json connector?
> >>>
> >>> Can you clarify if the difference here is in the Connector/Task
> classens,
> >>> or if it's in the key/value converters that are configured for the
> >>> connector? The key/value converters are configured using the
> >>> "key.converter" and "value.converter" property and, if problems arise
> >>> with
> >>> them, the task will fail and, if it has a non-empty ongoing
> transaction,
> >>> that transaction will be automatically aborted since we close the
> task's
> >>> Kafka producer when it fails (or shuts down gracefully).
> >>>
> >>> With regards to these log messages:
> >>>
> >>> > org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> producer with the same transactionalId which fences the current one.
> >>>
> >>> It looks like your tasks aren't shutting down gracefully in time, which
> >>> causes them to be fenced out by the Connect framework later on. Do you
> >>> see
> >>> messages like "Graceful stop of task <TASK ID HERE> failed" in the logs
> >>> for
> >>> your Connect worker?
> >>>
> >>> Cheers,
> >>>
> >>> Chris
> >>>
> >>> On Mon, Mar 13, 2023 at 10:58 AM NITTY BENNY <nittybe...@gmail.com>
> >>> wrote:
> >>>
> >>> > Hi Chris,
> >>> >
> >>> > As you said, the below message is coming when I call an abort if
> there
> >>> is
> >>> > an invalid record, then for the next transaction I can see the below
> >>> > message and then the connector will be stopped.
> >>> > 2023-03-13 14:28:26,043 INFO [json-sftp-source-connector|task-0]
> >>> Aborting
> >>> > transaction for batch as requested by connector
> >>> > (org.apache.kafka.connect.runtime.ExactlyOnceWorkerSourceTask)
> >>> > [task-thread-json-sftp-source-connector-0]
> >>> > 2023-03-13 14:28:26,043 INFO [json-sftp-source-connector|task-0]
> >>> [Producer
> >>> > clientId=connector-producer-json-sftp-source-connector-0,
> >>> > transactionalId=connect-cluster-json-sftp-source-connector-0]
> Aborting
> >>> > incomplete transaction
> >>> (org.apache.kafka.clients.producer.KafkaProducer)
> >>> > [task-thread-json-sftp-source-connector-0]
> >>> >
> >>> > The issue with InvalidProducerEpoch is happening when I call the
> >>> commit if
> >>> > there is an invalid record, and in the next transaction I am getting
> >>> > InvalidProducerEpoch Exception and the messages are copied in the
> >>> previous
> >>> > email. I don't know if this will also be fixed by your bug fix.I am
> >>> using
> >>> > kafka 3.3.1 version as of now.
> >>> >
> >>> > Thanks,
> >>> > Nitty
> >>> >
> >>> >
> >>> > On Mon, Mar 13, 2023 at 10:47 AM NITTY BENNY <nittybe...@gmail.com>
> >>> wrote:
> >>> >
> >>> > > Hi Chris,
> >>> > >
> >>> > > The below mentioned issue is happening for Json connector only. Is
> >>> there
> >>> > > any difference with asn1,binary,csv and json connector?
> >>> > >
> >>> > > Thanks,
> >>> > > Nitty
> >>> > >
> >>> > > On Mon, Mar 13, 2023 at 9:16 AM NITTY BENNY <nittybe...@gmail.com>
> >>> > wrote:
> >>> > >
> >>> > >> Hi Chris,
> >>> > >>
> >>> > >> Sorry Chris, I am not able to reproduce the above issue.
> >>> > >>
> >>> > >> I want to share with you one more use case I found.
> >>> > >> The use case is in the first batch it returns 2 valid records and
> >>> then
> >>> > in
> >>> > >> the next batch it is an invalid record.Below is the
> >>> transaction_state
> >>> > >> topic, when I call a commit while processing an invalid record.
> >>> > >>
> >>> > >>
> >>> >
> >>>
> connect-cluster-json-sftp-source-connector-0::TransactionMetadata(transactionalId=connect-cluster-json-sftp-source-connector-0,
> >>> > >> producerId=11, producerEpoch=2, txnTimeoutMs=60000,
> state=*Ongoing*,
> >>> > >> pendingState=None, topicPartitions=HashSet(streams-input-2),
> >>> > >> txnStartTimestamp=1678620463834,
> >>> txnLastUpdateTimestamp=1678620463834)
> >>> > >>
> >>> > >> then after some time I saw the below states as well,
> >>> > >>
> >>> > >>
> >>> >
> >>>
> connect-cluster-json-sftp-source-connector-0::TransactionMetadata(transactionalId=connect-cluster-json-sftp-source-connector-0,
> >>> > >> producerId=11, producerEpoch=3, txnTimeoutMs=60000,
> >>> > state=*PrepareAbort*,
> >>> > >> pendingState=None, topicPartitions=HashSet(streams-input-2),
> >>> > >> txnStartTimestamp=1678620463834,
> >>> txnLastUpdateTimestamp=1678620526119)
> >>> > >>
> >>> >
> >>>
> connect-cluster-json-sftp-source-connector-0::TransactionMetadata(transactionalId=connect-cluster-json-sftp-source-connector-0,
> >>> > >> producerId=11, producerEpoch=3, txnTimeoutMs=60000,
> >>> > state=*CompleteAbort*,
> >>> > >> pendingState=None, topicPartitions=HashSet(),
> >>> > >> txnStartTimestamp=1678620463834,
> >>> txnLastUpdateTimestamp=1678620526121)
> >>> > >>
> >>> > >> Later for the next transaction, when it returns the first batch
> >>> below is
> >>> > >> the logs I can see.
> >>> > >>
> >>> > >> Transiting to abortable error state due to
> >>> > >> org.apache.kafka.common.errors.InvalidProducerEpochException:
> >>> Producer
> >>> > >> attempted to produce with an old epoch.
> >>> > >> (org.apache.kafka.clients.producer.internals.TransactionManager)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> 2023-03-12 11:32:45,220 ERROR [json-sftp-source-connector|task-0]
> >>> > >> ExactlyOnceWorkerSourceTask{id=json-sftp-source-connector-0}
> failed
> >>> to
> >>> > send
> >>> > >> record to streams-input:
> >>> > >> (org.apache.kafka.connect.runtime.AbstractWorkerSourceTask)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> org.apache.kafka.common.errors.InvalidProducerEpochException:
> >>> Producer
> >>> > >> attempted to produce with an old epoch.
> >>> > >> 2023-03-12 11:32:45,222 INFO [json-sftp-source-connector|task-0]
> >>> > >> [Producer
> clientId=connector-producer-json-sftp-source-connector-0,
> >>> > >> transactionalId=connect-cluster-json-sftp-source-connector-0]
> >>> > Transiting to
> >>> > >> fatal error state due to
> >>> > >> org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> > >> producer with the same transactionalId which fences the current
> one.
> >>> > >> (org.apache.kafka.clients.producer.internals.TransactionManager)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> 2023-03-12 11:32:45,222 ERROR [json-sftp-source-connector|task-0]
> >>> > >> [Producer
> clientId=connector-producer-json-sftp-source-connector-0,
> >>> > >> transactionalId=connect-cluster-json-sftp-source-connector-0]
> >>> Aborting
> >>> > >> producer batches due to fatal error
> >>> > >> (org.apache.kafka.clients.producer.internals.Sender)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> > >> producer with the same transactionalId which fences the current
> one.
> >>> > >> 2023-03-12 11:32:45,222 ERROR [json-sftp-source-connector|task-0]
> >>> > >> ExactlyOnceWorkerSourceTask{id=json-sftp-source-connector-0}
> Failed
> >>> to
> >>> > >> flush offsets to storage:
> >>> > >> (org.apache.kafka.connect.runtime.ExactlyOnceWorkerSourceTask)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> > >> producer with the same transactionalId which fences the current
> one.
> >>> > >> 2023-03-12 11:32:45,224 ERROR [json-sftp-source-connector|task-0]
> >>> > >> ExactlyOnceWorkerSourceTask{id=json-sftp-source-connector-0}
> failed
> >>> to
> >>> > send
> >>> > >> record to streams-input:
> >>> > >> (org.apache.kafka.connect.runtime.AbstractWorkerSourceTask)
> >>> > >> [kafka-producer-network-thread |
> >>> > >> connector-producer-json-sftp-source-connector-0]
> >>> > >> org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> > >> producer with the same transactionalId which fences the current
> one.
> >>> > >> 2023-03-12 11:32:45,222 ERROR
> >>> > [json-sftp-source-connector|task-0|offsets]
> >>> > >> ExactlyOnceWorkerSourceTask{id=json-sftp-source-connector-0}
> Failed
> >>> to
> >>> > >> commit producer transaction
> >>> > >> (org.apache.kafka.connect.runtime.ExactlyOnceWorkerSourceTask)
> >>> > >> [task-thread-json-sftp-source-connector-0]
> >>> > >> org.apache.kafka.common.errors.ProducerFencedException: There is a
> >>> newer
> >>> > >> producer with the same transactionalId which fences the current
> one.
> >>> > >> 2023-03-12 11:32:45,225 ERROR [json-sftp-source-connector|task-0]
> >>> > >> ExactlyOnceWorkerSourceTask{id=json-sftp-source-connector-0} Task
> >>> threw
> >>> > an
> >>> > >> uncaught and unrecoverable exception. Task is being killed and
> will
> >>> not
> >>> > >> recover until manually restarted
> >>> > >> (org.apache.kafka.connect.runtime.WorkerTask)
> >>> > >> [task-thread-json-sftp-source-connector-0]
> >>> > >>
> >>> > >> Do you know why it is showing an abort state even if I call
> commit?
> >>> > >>
> >>> > >> I tested one more scenario, When I call the commit I saw the below
> >>> > >>
> >>> >
> >>>
> connect-cluster-json-sftp-source-connector-0::TransactionMetadata(transactionalId=connect-cluster-json-sftp-source-connector-0,
> >>> > >> producerId=11, producerEpoch=2, txnTimeoutMs=60000,
> state=*Ongoing*,
> >>> > >> pendingState=None, topicPartitions=HashSet(streams-input-2),
> >>> > >> txnStartTimestamp=1678620463834,
> >>> txnLastUpdateTimestamp=1678620463834)
> >>> > >> Then, before changing the states to Abort, I dropped the next file
> >>> then
> >>> > I
> >>> > >> dont see any issues. Previous transaction
> >>> > >> as well as the current transaction are committed.
> >>> > >>
> >>> > >> Thank you for your support.
> >>> > >>
> >>> > >> Thanks,
> >>> > >> Nitty
> >>> > >>
> >>> > >> On Fri, Mar 10, 2023 at 8:04 PM Chris Egerton
> >>> <chr...@aiven.io.invalid>
> >>> > >> wrote:
> >>> > >>
> >>> > >>> Hi Nitty,
> >>> > >>>
> >>> > >>> > I called commitTransaction when I reach the first error record,
> >>> but
> >>> > >>> commit is not happening for me. Kafka connect tries to abort the
> >>> > >>> transaction automatically
> >>> > >>>
> >>> > >>> This is really interesting--are you certain that your task never
> >>> > invoked
> >>> > >>> TransactionContext::abortTransaction in this case? I'm looking
> >>> over the
> >>> > >>> code base and it seems fairly clear that the only thing that
> could
> >>> > >>> trigger
> >>> > >>> a call to KafkaProducer::abortTransaction is a request by the
> task
> >>> to
> >>> > >>> abort
> >>> > >>> a transaction (either for a next batch, or for a specific
> record).
> >>> It
> >>> > may
> >>> > >>> help to run the connector in a debugger and/or look for "Aborting
> >>> > >>> transaction for batch as requested by connector" or "Aborting
> >>> > transaction
> >>> > >>> for record on topic <TOPIC NAME HERE> as requested by connector"
> >>> log
> >>> > >>> messages (which will be emitted at INFO level by
> >>> > >>> the org.apache.kafka.connect.runtime.ExactlyOnceWorkerSourceTask
> >>> class
> >>> > if
> >>> > >>> the task is requesting an abort).
> >>> > >>>
> >>> > >>> Regardless, I'll work on a fix for the bug with aborting empty
> >>> > >>> transactions. Thanks for helping uncover that one!
> >>> > >>>
> >>> > >>> Cheers,
> >>> > >>>
> >>> > >>> Chris
> >>> > >>>
> >>> > >>> On Thu, Mar 9, 2023 at 6:36 PM NITTY BENNY <nittybe...@gmail.com
> >
> >>> > wrote:
> >>> > >>>
> >>> > >>> > Hi Chris,
> >>> > >>> >
> >>> > >>> > We have a use case to commit previous successful records and
> >>> stop the
> >>> > >>> > processing of the current file and move on with the next file.
> To
> >>> > >>> achieve
> >>> > >>> > that I called commitTransaction when I reach the first error
> >>> record,
> >>> > >>> but
> >>> > >>> > commit is not happening for me. Kafka connect tries to abort
> the
> >>> > >>> > transaction automatically, I checked the _transaction_state
> >>> topic and
> >>> > >>> > states marked as PrepareAbort and CompleteAbort. Do you know
> why
> >>> > kafka
> >>> > >>> > connect automatically invokes abort instead of the implicit
> >>> commit I
> >>> > >>> > called?
> >>> > >>> > Then as a result, when I tries to parse the next file - say
> ABC,
> >>> I
> >>> > saw
> >>> > >>> the
> >>> > >>> > logs "Aborting incomplete transaction" and ERROR: "Failed to
> sent
> >>> > >>> record to
> >>> > >>> > topic", and we lost the first batch of records from the current
> >>> > >>> transaction
> >>> > >>> > in the file ABC.
> >>> > >>> >
> >>> > >>> > Is it possible that there's a case where an abort is being
> >>> requested
> >>> > >>> while
> >>> > >>> > the current transaction is empty (i.e., the task hasn't
> returned
> >>> any
> >>> > >>> > records from SourceTask::poll since the last transaction was
> >>> > >>> > committed/aborted)? --- Yes, that case is possible for us.
> There
> >>> is a
> >>> > >>> case
> >>> > >>> > where the first record itself an error record.
> >>> > >>> >
> >>> > >>> > Thanks,
> >>> > >>> > Nitty
> >>> > >>> >
> >>> > >>> > On Thu, Mar 9, 2023 at 3:48 PM Chris Egerton
> >>> <chr...@aiven.io.invalid
> >>> > >
> >>> > >>> > wrote:
> >>> > >>> >
> >>> > >>> > > Hi Nitty,
> >>> > >>> > >
> >>> > >>> > > Thanks for the code examples and the detailed explanations,
> >>> this is
> >>> > >>> > really
> >>> > >>> > > helpful!
> >>> > >>> > >
> >>> > >>> > > > Say if I have a file with 5 records and batch size is 2,
> and
> >>> in
> >>> > my
> >>> > >>> 3rd
> >>> > >>> > > batch I have one error record then in that batch, I dont
> have a
> >>> > valid
> >>> > >>> > > record to call commit or abort. But I want to commit all the
> >>> > previous
> >>> > >>> > > batches that were successfully parsed. How do I do that?
> >>> > >>> > >
> >>> > >>> > > An important thing to keep in mind with the
> TransactionContext
> >>> API
> >>> > is
> >>> > >>> > that
> >>> > >>> > > all records that a task returns from SourceTask::poll are
> >>> > implicitly
> >>> > >>> > > included in a transaction. Invoking
> >>> > >>> SourceTaskContext::transactionContext
> >>> > >>> > > doesn't alter this or cause transactions to start being used;
> >>> > >>> everything
> >>> > >>> > is
> >>> > >>> > > already in a transaction, and the Connect runtime
> automatically
> >>> > >>> begins
> >>> > >>> > > transactions for any records it sees from the task if it
> hasn't
> >>> > >>> already
> >>> > >>> > > begun one. It's also valid to return a null or empty list of
> >>> > records
> >>> > >>> from
> >>> > >>> > > SourceTask::poll. So in this case, you can invoke
> >>> > >>> > > transactionContext.commitTransaction() (the no-args variant)
> >>> and
> >>> > >>> return
> >>> > >>> > an
> >>> > >>> > > empty batch from SourceTask::poll, which will cause the
> >>> transaction
> >>> > >>> > > containing the 4 valid records that were returned in the
> last 2
> >>> > >>> batches
> >>> > >>> > to
> >>> > >>> > > be committed.
> >>> > >>> > >
> >>> > >>> > > FWIW, I would be a little cautious about this approach. Many
> >>> times
> >>> > >>> it's
> >>> > >>> > > better to fail fast on invalid data; it might be worth it to
> at
> >>> > least
> >>> > >>> > allow
> >>> > >>> > > users to configure whether the connector fails on invalid
> >>> data, or
> >>> > >>> > silently
> >>> > >>> > > skips over it (which is what happens when transactions are
> >>> > aborted).
> >>> > >>> > >
> >>> > >>> > > > Why is abort not working without adding the last record to
> >>> the
> >>> > >>> list?
> >>> > >>> > >
> >>> > >>> > > Is it possible that there's a case where an abort is being
> >>> > requested
> >>> > >>> > while
> >>> > >>> > > the current transaction is empty (i.e., the task hasn't
> >>> returned
> >>> > any
> >>> > >>> > > records from SourceTask::poll since the last transaction was
> >>> > >>> > > committed/aborted)? I think this may be a bug in the Connect
> >>> > >>> framework
> >>> > >>> > > where we don't check to see if a transaction is already open
> >>> when a
> >>> > >>> task
> >>> > >>> > > requests that a transaction be aborted, which can cause tasks
> >>> to
> >>> > fail
> >>> > >>> > (see
> >>> > >>> > > https://issues.apache.org/jira/browse/KAFKA-14799 for more
> >>> > details).
> >>> > >>> > >
> >>> > >>> > > Cheers,
> >>> > >>> > >
> >>> > >>> > > Chris
> >>> > >>> > >
> >>> > >>> > >
> >>> > >>> > > On Wed, Mar 8, 2023 at 6:44 PM NITTY BENNY <
> >>> nittybe...@gmail.com>
> >>> > >>> wrote:
> >>> > >>> > >
> >>> > >>> > > > Hi Chris,
> >>> > >>> > > >
> >>> > >>> > > > I am not sure if you are able to see the images I shared
> with
> >>> > you .
> >>> > >>> > > > Copying the code snippet below,
> >>> > >>> > > >
> >>> > >>> > > > if (expectedRecordCount >= 0) {
> >>> > >>> > > > int missingCount = expectedRecordCount - (int)
> >>> this.
> >>> > >>> > > > recordOffset() - 1;
> >>> > >>> > > > if (missingCount > 0) {
> >>> > >>> > > > if (transactionContext != null) {
> >>> > >>> > > > isMissedRecords = true;
> >>> > >>> > > > } else {
> >>> > >>> > > > throw new
> >>> DataException(String.format("Missing %d
> >>> > >>> > records
> >>> > >>> > > > (expecting %d, actual %d)", missingCount,
> >>> expectedRecordCount,
> >>> > >>> this.
> >>> > >>> > > > recordOffset()));
> >>> > >>> > > > }
> >>> > >>> > > > } else if (missingCount < 0) {
> >>> > >>> > > > if (transactionContext != null) {
> >>> > >>> > > > isMissedRecords = true;
> >>> > >>> > > > } else {
> >>> > >>> > > > throw new DataException(String.format("Too
> >>> many
> >>> > >>> records
> >>> > >>> > > > (expecting %d, actual %d)", expectedRecordCount,
> >>> > >>> this.recordOffset()));
> >>> > >>> > > > }
> >>> > >>> > > > }
> >>> > >>> > > > }
> >>> > >>> > > > addLastRecord(records, null, value);
> >>> > >>> > > > }
> >>> > >>> > > >
> >>> > >>> > > >
> >>> > >>> > > >
> >>> > >>> > > > //asn1 or binary abort
> >>> > >>> > > > if((config.parseErrorThreshold != null &&
> >>> parseErrorCount
> >>> > >>> >=
> >>> > >>> > > > config.parseErrorThreshold
> >>> > >>> > > > && lastbatch && transactionContext != null) ||
> >>> > >>> (isMissedRecords
> >>> > >>> > > > && transactionContext != null && lastbatch)) {
> >>> > >>> > > > log.info("Transaction is aborting");
> >>> > >>> > > > log.info("records = {}", records);
> >>> > >>> > > > if (!records.isEmpty()) {
> >>> > >>> > > > log.info("with record");
> >>> > >>> > > >
> >>> > >>> > > transactionContext.abortTransaction(records.get(records.size
> >>> > >>> > > > ()-1));
> >>> > >>> > > > } else {
> >>> > >>> > > > log.info("without record");
> >>> > >>> > > > transactionContext.abortTransaction();
> >>> > >>> > > > }
> >>> > >>> > > >
> >>> > >>> > > > Thanks,
> >>> > >>> > > > Nitty
> >>> > >>> > > >
> >>> > >>> > > > On Wed, Mar 8, 2023 at 11:38 PM NITTY BENNY <
> >>> > nittybe...@gmail.com>
> >>> > >>> > > wrote:
> >>> > >>> > > >
> >>> > >>> > > >> Hi Chris,
> >>> > >>> > > >> Sorry for the typo in my previous email.
> >>> > >>> > > >>
> >>> > >>> > > >> Regarding the point 2,* the task returns a batch of
> records
> >>> from
> >>> > >>> > > >> SourceTask::poll (and, if using*
> >>> > >>> > > >>
> >>> > >>> > > >>
> >>> > >>> > > >> *the per-record API provided by the TransactionContext
> >>> class,
> >>> > >>> includes
> >>> > >>> > > >> atleast one record that should trigger a transaction
> >>> > commit/abort
> >>> > >>> in
> >>> > >>> > > >> thatbatch)*
> >>> > >>> > > >> What if I am using the API without passing a record? We
> >>> have 2
> >>> > >>> types
> >>> > >>> > of
> >>> > >>> > > >> use cases, one where on encountering an error record, we
> >>> want to
> >>> > >>> > commit
> >>> > >>> > > >> previous successful batches and disregard the failed
> record
> >>> and
> >>> > >>> > upcoming
> >>> > >>> > > >> batches. In this case we created the transactionContext
> just
> >>> > >>> before
> >>> > >>> > > reading
> >>> > >>> > > >> the file (file is our transaction boundary).Say if I have
> a
> >>> file
> >>> > >>> with
> >>> > >>> > 5
> >>> > >>> > > >> records and batch size is 2, and in my 3rd batch I have
> one
> >>> > error
> >>> > >>> > record
> >>> > >>> > > >> then in that batch, I dont have a valid record to call
> >>> commit or
> >>> > >>> > abort.
> >>> > >>> > > But
> >>> > >>> > > >> I want to commit all the previous batches that were
> >>> successfully
> >>> > >>> > parsed.
> >>> > >>> > > >> How do I do that?
> >>> > >>> > > >>
> >>> > >>> > > >> Second use case is where I want to abort a transaction if
> >>> the
> >>> > >>> record
> >>> > >>> > > >> count doesn't match.
> >>> > >>> > > >> Code Snippet :
> >>> > >>> > > >> [image: image.png]
> >>> > >>> > > >> There are no error records in this case. If you see I
> added
> >>> the
> >>> > >>> > > condition
> >>> > >>> > > >> of transactionContext check to implement exactly once,
> >>> without
> >>> > >>> > > >> transaction it was just throwing the exception without
> >>> calling
> >>> > the
> >>> > >>> > > >> addLastRecord() method and in the catch block it just logs
> >>> the
> >>> > >>> message
> >>> > >>> > > and
> >>> > >>> > > >> return the list of records without the last record to
> >>> poll().To
> >>> > >>> make
> >>> > >>> > it
> >>> > >>> > > >> work, I called the method addLastRecord() in this case, so
> >>> it is
> >>> > >>> not
> >>> > >>> > > >> throwing the exception and list has last record as well.
> >>> Then I
> >>> > >>> called
> >>> > >>> > > the
> >>> > >>> > > >> abort, everything got aborted. Why is abort not working
> >>> without
> >>> > >>> adding
> >>> > >>> > > the
> >>> > >>> > > >> last record to the list?
> >>> > >>> > > >> [image: image.png]
> >>> > >>> > > >>
> >>> > >>> > > >> Code to call abort.
> >>> > >>> > > >>
> >>> > >>> > > >>
> >>> > >>> > > >>
> >>> > >>> > > >>
> >>> > >>> > > >> Thanks,
> >>> > >>> > > >> Nitty
> >>> > >>> > > >>
> >>> > >>> > > >> On Wed, Mar 8, 2023 at 4:26 PM Chris Egerton
> >>> > >>> <chr...@aiven.io.invalid
> >>> > >>> > >
> >>> > >>> > > >> wrote:
> >>> > >>> > > >>
> >>> > >>> > > >>> Hi Nitty,
> >>> > >>> > > >>>
> >>> > >>> > > >>> I'm a little confused about what you mean by this part:
> >>> > >>> > > >>>
> >>> > >>> > > >>> > transaction is not getting completed because it is not
> >>> > >>> commiting
> >>> > >>> > the
> >>> > >>> > > >>> transaction offest.
> >>> > >>> > > >>>
> >>> > >>> > > >>> The only conditions required for a transaction to be
> >>> completed
> >>> > >>> when a
> >>> > >>> > > >>> connector is defining its own transaction boundaries are:
> >>> > >>> > > >>>
> >>> > >>> > > >>> 1. The task requests a transaction commit/abort from the
> >>> > >>> > > >>> TransactionContext
> >>> > >>> > > >>> 2. The task returns a batch of records from
> >>> SourceTask::poll
> >>> > >>> (and, if
> >>> > >>> > > >>> using
> >>> > >>> > > >>> the per-record API provided by the TransactionContext
> >>> class,
> >>> > >>> includes
> >>> > >>> > > at
> >>> > >>> > > >>> least one record that should trigger a transaction
> >>> commit/abort
> >>> > >>> in
> >>> > >>> > that
> >>> > >>> > > >>> batch)
> >>> > >>> > > >>>
> >>> > >>> > > >>> The Connect runtime should automatically commit source
> >>> offsets
> >>> > to
> >>> > >>> > Kafka
> >>> > >>> > > >>> whenever a transaction is completed, either by commit or
> >>> abort.
> >>> > >>> This
> >>> > >>> > is
> >>> > >>> > > >>> because transactions should only be aborted for data that
> >>> > should
> >>> > >>> > never
> >>> > >>> > > be
> >>> > >>> > > >>> re-read by the connector; if there is a validation error
> >>> that
> >>> > >>> should
> >>> > >>> > be
> >>> > >>> > > >>> handled by reconfiguring the connector, then the task
> >>> should
> >>> > >>> throw an
> >>> > >>> > > >>> exception instead of aborting the transaction.
> >>> > >>> > > >>>
> >>> > >>> > > >>> If possible, do you think you could provide a brief code
> >>> > snippet
> >>> > >>> > > >>> illustrating what your task is doing that's causing
> issues?
> >>> > >>> > > >>>
> >>> > >>> > > >>> Cheers,
> >>> > >>> > > >>>
> >>> > >>> > > >>> Chris (not Chrise 🙂)
> >>> > >>> > > >>>
> >>> > >>> > > >>> On Tue, Mar 7, 2023 at 10:17 AM NITTY BENNY <
> >>> > >>> nittybe...@gmail.com>
> >>> > >>> > > >>> wrote:
> >>> > >>> > > >>>
> >>> > >>> > > >>> > Hi Chrise,
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > Thanks for sharing the details.
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > Regarding the use case, For Asn1 source connector we
> >>> have a
> >>> > use
> >>> > >>> > case
> >>> > >>> > > to
> >>> > >>> > > >>> > validate number of records in the file with the number
> of
> >>> > >>> records
> >>> > >>> > in
> >>> > >>> > > >>> the
> >>> > >>> > > >>> > header. So currently, if validation fails we are not
> >>> sending
> >>> > >>> the
> >>> > >>> > last
> >>> > >>> > > >>> > record to the topic. But after introducing exactly once
> >>> with
> >>> > >>> > > connector
> >>> > >>> > > >>> > transaction boundary, I can see that if I call an abort
> >>> when
> >>> > >>> the
> >>> > >>> > > >>> validation
> >>> > >>> > > >>> > fails, transaction is not getting completed because it
> >>> is not
> >>> > >>> > > >>> commiting the
> >>> > >>> > > >>> > transaction offest. I saw that transaction state
> changed
> >>> to
> >>> > >>> > > >>> CompleteAbort.
> >>> > >>> > > >>> > So for my next transaction I am getting
> >>> > >>> > InvalidProducerEpochException
> >>> > >>> > > >>> and
> >>> > >>> > > >>> > then task stopped after that. I tried calling the abort
> >>> after
> >>> > >>> > sending
> >>> > >>> > > >>> last
> >>> > >>> > > >>> > record to the topic then transaction getting completed.
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > I dont know if I am doing anything wrong here.
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > Please advise.
> >>> > >>> > > >>> > Thanks,
> >>> > >>> > > >>> > Nitty
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > On Tue 7 Mar 2023 at 2:21 p.m., Chris Egerton
> >>> > >>> > > <chr...@aiven.io.invalid
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > wrote:
> >>> > >>> > > >>> >
> >>> > >>> > > >>> > > Hi Nitty,
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > We've recently added some documentation on
> implementing
> >>> > >>> > > exactly-once
> >>> > >>> > > >>> > source
> >>> > >>> > > >>> > > connectors here:
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> >
> >>> > >>> > > >>>
> >>> > >>> > >
> >>> > >>> >
> >>> > >>>
> >>> >
> >>>
> https://kafka.apache.org/documentation/#connect_exactlyoncesourceconnectors
> >>> > >>> > > >>> > > .
> >>> > >>> > > >>> > > To quote a relevant passage from those docs:
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > > In order for a source connector to take advantage
> of
> >>> this
> >>> > >>> > > support,
> >>> > >>> > > >>> it
> >>> > >>> > > >>> > > must be able to provide meaningful source offsets for
> >>> each
> >>> > >>> record
> >>> > >>> > > >>> that it
> >>> > >>> > > >>> > > emits, and resume consumption from the external
> system
> >>> at
> >>> > the
> >>> > >>> > exact
> >>> > >>> > > >>> > > position corresponding to any of those offsets
> without
> >>> > >>> dropping
> >>> > >>> > or
> >>> > >>> > > >>> > > duplicating messages.
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > So, as long as your source connector is able to use
> the
> >>> > Kafka
> >>> > >>> > > Connect
> >>> > >>> > > >>> > > framework's offsets API correctly, it shouldn't be
> >>> > necessary
> >>> > >>> to
> >>> > >>> > > make
> >>> > >>> > > >>> any
> >>> > >>> > > >>> > > other code changes to the connector.
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > To enable exactly-once support for source connectors
> on
> >>> > your
> >>> > >>> > > Connect
> >>> > >>> > > >>> > > cluster, see the docs section here:
> >>> > >>> > > >>> > >
> >>> > >>> >
> >>> https://kafka.apache.org/documentation/#connect_exactlyoncesource
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > With regard to transactions, a transactional producer
> >>> is
> >>> > >>> always
> >>> > >>> > > >>> created
> >>> > >>> > > >>> > > automatically for your connector by the Connect
> runtime
> >>> > when
> >>> > >>> > > >>> exactly-once
> >>> > >>> > > >>> > > support is enabled on the worker. The only reason to
> >>> set
> >>> > >>> > > >>> > > "transaction.boundary" to "connector" is if your
> >>> connector
> >>> > >>> would
> >>> > >>> > > >>> like to
> >>> > >>> > > >>> > > explicitly define its own transaction boundaries. In
> >>> this
> >>> > >>> case,
> >>> > >>> > it
> >>> > >>> > > >>> sounds
> >>> > >>> > > >>> > > like may be what you want; I just want to make sure
> to
> >>> call
> >>> > >>> out
> >>> > >>> > > that
> >>> > >>> > > >>> in
> >>> > >>> > > >>> > > either case, you should not be directly
> instantiating a
> >>> > >>> producer
> >>> > >>> > in
> >>> > >>> > > >>> your
> >>> > >>> > > >>> > > connector code, but let the Kafka Connect runtime do
> >>> that
> >>> > for
> >>> > >>> > you,
> >>> > >>> > > >>> and
> >>> > >>> > > >>> > just
> >>> > >>> > > >>> > > worry about returning the right records from
> >>> > SourceTask::poll
> >>> > >>> > (and
> >>> > >>> > > >>> > possibly
> >>> > >>> > > >>> > > defining custom transactions using the
> >>> TransactionContext
> >>> > >>> API).
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > With respect to your question about committing or
> >>> aborting
> >>> > in
> >>> > >>> > > certain
> >>> > >>> > > >>> > > circumstances, it'd be useful to know more about your
> >>> use
> >>> > >>> case,
> >>> > >>> > > >>> since it
> >>> > >>> > > >>> > > may not be necessary to define custom transaction
> >>> > boundaries
> >>> > >>> in
> >>> > >>> > > your
> >>> > >>> > > >>> > > connector at all.
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > Cheers,
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > Chris
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > On Tue, Mar 7, 2023 at 7:21 AM NITTY BENNY <
> >>> > >>> nittybe...@gmail.com
> >>> > >>> > >
> >>> > >>> > > >>> wrote:
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> > > > Hi Team,
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > Adding on top of this, I tried creating a
> >>> > >>> TransactionContext
> >>> > >>> > > >>> object and
> >>> > >>> > > >>> > > > calling the commitTransaction and abortTranaction
> >>> methods
> >>> > >>> in
> >>> > >>> > > source
> >>> > >>> > > >>> > > > connectors.
> >>> > >>> > > >>> > > > But the main problem I saw is that if there is any
> >>> error
> >>> > >>> while
> >>> > >>> > > >>> parsing
> >>> > >>> > > >>> > > the
> >>> > >>> > > >>> > > > record, connect is calling an abort but we have a
> use
> >>> > case
> >>> > >>> to
> >>> > >>> > > call
> >>> > >>> > > >>> > commit
> >>> > >>> > > >>> > > > in some cases. Is it a valid use case in terms of
> >>> kafka
> >>> > >>> > connect?
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > Another Question - Should I use a transactional
> >>> producer
> >>> > >>> > instead
> >>> > >>> > > >>> > > > creating an object of TransactionContext? Below is
> >>> the
> >>> > >>> > connector
> >>> > >>> > > >>> > > > configuration I am using.
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > exactly.once.support: "required"
> >>> > >>> > > >>> > > > transaction.boundary: "connector"
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > Could you please help me here?
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > Thanks,
> >>> > >>> > > >>> > > > Nitty
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > On Tue, Mar 7, 2023 at 12:29 AM NITTY BENNY <
> >>> > >>> > > nittybe...@gmail.com>
> >>> > >>> > > >>> > > wrote:
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > > > > Hi Team,
> >>> > >>> > > >>> > > > > I am trying to implement exactly once behavior in
> >>> our
> >>> > >>> source
> >>> > >>> > > >>> > connector.
> >>> > >>> > > >>> > > > Is
> >>> > >>> > > >>> > > > > there any sample source connector implementation
> >>> > >>> available to
> >>> > >>> > > >>> have a
> >>> > >>> > > >>> > > look
> >>> > >>> > > >>> > > > > at?
> >>> > >>> > > >>> > > > > Regards,
> >>> > >>> > > >>> > > > > Nitty
> >>> > >>> > > >>> > > > >
> >>> > >>> > > >>> > > >
> >>> > >>> > > >>> > >
> >>> > >>> > > >>> >
> >>> > >>> > > >>>
> >>> > >>> > > >>
> >>> > >>> > >
> >>> > >>> >
> >>> > >>>
> >>> > >>
> >>> >
> >>>
> >>
>
