recover from svaepoint
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HI: When "sink.semantic = exactly-once", the following exception is thrown when recovering from svaepoint public static final String KAFKA_TABLE_FORMAT = "CREATE TABLE "+TABLE_NAME+" (\n" + " "+COLUMN_NAME+" STRING\n" + ") WITH (\n" + " 'connector' = 'kafka',\n" + " 'topic' = '%s',\n" + " 'properties.bootstrap.servers' = '%s',\n" + " 'sink.semantic' = 'exactly-once',\n" + " 'properties.transaction.timeout.ms' = '900000',\n" + " 'sink.partitioner' = 'com.woqutench.qmatrix.cdc.extractor.PkPartitioner',\n" + " 'format' = 'dbz-json'\n" + ")\n"; [] - Source: TableSourceScan(table=[[default_catalog, default_database, debezium_source]], fields=[data]) -> Sink: Sink(table=[default_catalog.default_database.KafkaTable], fields=[data]) (1/1)#859 (075273be72ab01bf1afd3c066876aaa6) switched from INITIALIZING to FAILED with failure cause: org.apache.kafka.common.KafkaException: Unexpected error in InitProducerIdResponse; Producer attempted an operation with an old epoch. Either there is a newer producer with the same transactionalId, or the producer's transaction has been expired by the broker. at org.apache.kafka.clients.producer.internals.TransactionManager$InitProducerIdHandler.handleResponse(TransactionManager.java:1352) at org.apache.kafka.clients.producer.internals.TransactionManager$TxnRequestHandler.onComplete(TransactionManager.java:1260) at org.apache.kafka.clients.ClientResponse.onComplete(ClientResponse.java:109) at org.apache.kafka.clients.NetworkClient.completeResponses(NetworkClient.java:572) at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:564) at org.apache.kafka.clients.producer.internals.Sender.maybeSendAndPollTransactionalRequest(Sender.java:414) at org.apache.kafka.clients.producer.internals.Sender.runOnce(Sender.java:312) at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:239) at java.lang.Thread.run(Thread.java:748) |
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The error message says that we are trying to reuse a transaction id that is currently being used or has expired. I am not 100% sure how this can happen. My suspicion is that you have resumed a job multiple times from the same savepoint. Have you checked that there is no other job which has been resumed from the same savepoint and which is currently running or has run and completed checkpoints? [hidden email] [hidden email] how does the transaction id generation ensures that we don't have a clash of transaction ids if we resume the same job multiple times from the same savepoint? From the code, I do see that we have a TransactionalIdsGenerator which is initialized with the taskName and the operator UID. fyi: [hidden email] Cheers, Till On Mon, May 31, 2021 at 11:10 AM 周瑞 <[hidden email]> wrote:
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Hi, I think there is no generic way. If this error has happened indeed after starting a second job from the same savepoint, or something like that, user can change Sink's operator UID. If this is an issue of intentional recovery from an earlier checkpoint/savepoint, maybe `FlinkKafkaProducer#setLogFailuresOnly` will be helpful. Best, Piotrek wt., 1 cze 2021 o 15:16 Till Rohrmann <[hidden email]> napisał(a): The error message says that we are trying to reuse a transaction id that is |
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Forwarding 周瑞's message to a duplicate thread: After our analysis, we found a bug in the org.apache.flink.streaming.connectors.kafka.internals.FlinkKafkaInternalProducer.resumeTransaction method The analysis process is as follows： org.apache.flink.streaming.api.functions.sink.TwoPhaseCommitSinkFunction public void initializeState(FunctionInitializationContext context) throws Exception { state = context.getOperatorStateStore().getListState(stateDescriptor); boolean recoveredUserContext = false; if (context.isRestored()) { LOG.info("{} - restoring state", name()); for (State<TXN, CONTEXT> operatorState : state.get()) { userContext = operatorState.getContext(); List<TransactionHolder<TXN>> recoveredTransactions = operatorState.getPendingCommitTransactions(); List<TXN> handledTransactions = new ArrayList<>(recoveredTransactions.size() + 1); for (TransactionHolder<TXN> recoveredTransaction : recoveredTransactions) { // If this fails to succeed eventually, there is actually data loss recoverAndCommitInternal(recoveredTransaction); handledTransactions.add(recoveredTransaction.handle); LOG.info("{} committed recovered transaction {}", name(), recoveredTransaction); } { TXN transaction = operatorState.getPendingTransaction().handle; recoverAndAbort(transaction); handledTransactions.add(transaction); LOG.info( "{} aborted recovered transaction {}", name(), operatorState.getPendingTransaction()); } if (userContext.isPresent()) { finishRecoveringContext(handledTransactions); recoveredUserContext = true; } } } (1)recoverAndCommitInternal(recoveredTransaction); The previous transactionalid, producerId and epoch in the state are used to commit the transaction,However, we find that the producerIdAndEpoch of transactionManager is a static constant (ProducerIdAndEpoch.NONE), which pollutes the static constant ProducerIdAndEpoch.NONE @Override protected void recoverAndCommit(FlinkKafkaProducer.KafkaTransactionState transaction) { if (transaction.isTransactional()) { FlinkKafkaInternalProducer<byte[], byte[]> producer = null; try { producer = initTransactionalProducer(transaction.transactionalId, false); producer.resumeTransaction(transaction.producerId, transaction.epoch); producer.commitTransaction(); } catch (InvalidTxnStateException | ProducerFencedException ex) { // That means we have committed this transaction before. LOG.warn( "Encountered error {} while recovering transaction {}. " + "Presumably this transaction has been already committed before", ex, transaction); } finally { if (producer != null) { producer.close(0, TimeUnit.SECONDS); } } } } public void resumeTransaction(long producerId, short epoch) { synchronized (producerClosingLock) { ensureNotClosed(); Preconditions.checkState( producerId >= 0 && epoch >= 0, "Incorrect values for producerId %s and epoch %s", producerId, epoch); LOG.info( "Attempting to resume transaction {} with producerId {} and epoch {}", transactionalId, producerId, epoch); Object transactionManager = getField(kafkaProducer, "transactionManager"); synchronized (transactionManager) { Object topicPartitionBookkeeper = getField(transactionManager, "topicPartitionBookkeeper"); invoke( transactionManager, "transitionTo", getEnum( "org.apache.kafka.clients.producer.internals.TransactionManager$State.INITIALIZING")); invoke(topicPartitionBookkeeper, "reset"); Object producerIdAndEpoch = getField(transactionManager, "producerIdAndEpoch"); setField(producerIdAndEpoch, "producerId", producerId); setField(producerIdAndEpoch, "epoch", epoch); invoke( transactionManager, "transitionTo", getEnum( "org.apache.kafka.clients.producer.internals.TransactionManager$State.READY")); invoke( transactionManager, "transitionTo", getEnum( "org.apache.kafka.clients.producer.internals.TransactionManager$State.IN_TRANSACTION")); setField(transactionManager, "transactionStarted", true); } } } public TransactionManager(LogContext logContext, String transactionalId, int transactionTimeoutMs, long retryBackoffMs, ApiVersions apiVersions) { this.producerIdAndEpoch = ProducerIdAndEpoch.NONE; this.transactionalId = transactionalId; this.log = logContext.logger(TransactionManager.class); this.transactionTimeoutMs = transactionTimeoutMs; this.transactionCoordinator = null; this.consumerGroupCoordinator = null; this.newPartitionsInTransaction = new HashSet<>(); this.pendingPartitionsInTransaction = new HashSet<>(); this.partitionsInTransaction = new HashSet<>(); this.pendingRequests = new PriorityQueue<>(10, Comparator.comparingInt(o -> o.priority().priority)); this.pendingTxnOffsetCommits = new HashMap<>(); this.partitionsWithUnresolvedSequences = new HashMap<>(); this.partitionsToRewriteSequences = new HashSet<>(); this.retryBackoffMs = retryBackoffMs; this.topicPartitionBookkeeper = new TopicPartitionBookkeeper(); this.apiVersions = apiVersions; } public class ProducerIdAndEpoch { public static final ProducerIdAndEpoch NONE = new ProducerIdAndEpoch(RecordBatch.NO_PRODUCER_ID, RecordBatch.NO_PRODUCER_EPOCH); public final long producerId; public final short epoch; public ProducerIdAndEpoch(long producerId, short epoch) { this.producerId = producerId; this.epoch = epoch; } public boolean isValid() { return RecordBatch.NO_PRODUCER_ID < producerId; } @Override public String toString() { return "(producerId=" + producerId + ", epoch=" + epoch + ")"; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; ProducerIdAndEpoch that = (ProducerIdAndEpoch) o; if (producerId != that.producerId) return false; return epoch == that.epoch; } @Override public int hashCode() { int result = (int) (producerId ^ (producerId >>> 32)); result = 31 * result + (int) epoch; return result; } } （2）In the second step, recoverAndAbort(FlinkKafkaProducer.KafkaTransactionState transaction), when initializing the transaction, producerId and epoch in the first step pollute ProducerIdAndEpoch.NONE. Therefore, when an initialization request is sent to Kafka, the values of the producerId and epoch variables in the request parameter ProducerIdAndEpoch.NONE are equal to the values of the producerId and epoch variables in the first transaction commit, not equal to - 1, - 1. So Kafka throws an exception: Unexpected error in InitProducerIdResponse; Producer attempted an operation with an old epoch. Either there is a newer producer with the same transactionalId, or the producer's transaction has been expired by the broker. at org.apache.kafka.clients.producer.internals.TransactionManager$InitProducerIdHandler.handleResponse(TransactionManager.java:1352) at org.apache.kafka.clients.producer.internals.TransactionManager$TxnRequestHandler.onComplete(TransactionManager.java:1260) at org.apache.kafka.clients.ClientResponse.onComplete(ClientResponse.java:109) at org.apache.kafka.clients.NetworkClient.completeResponses(NetworkClient.java:572) at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:564) at org.apache.kafka.clients.producer.internals.Sender.maybeSendAndPollTransactionalRequest(Sender.java:414) at org.apache.kafka.clients.producer.internals.Sender.runOnce(Sender.java:312) at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:239) at java.lang.Thread.run(Thread.java:748) protected void recoverAndAbort(FlinkKafkaProducer.KafkaTransactionState transaction) { if (transaction.isTransactional()) { FlinkKafkaInternalProducer<byte[], byte[]> producer = null; try { producer = initTransactionalProducer(transaction.transactionalId, false); producer.initTransactions(); } finally { if (producer != null) { producer.close(0, TimeUnit.SECONDS); } } } } public synchronized TransactionalRequestResult initializeTransactions() { return initializeTransactions(ProducerIdAndEpoch.NONE); } synchronized TransactionalRequestResult initializeTransactions(ProducerIdAndEpoch producerIdAndEpoch) { boolean isEpochBump = producerIdAndEpoch != ProducerIdAndEpoch.NONE; return handleCachedTransactionRequestResult(() -> { // If this is an epoch bump, we will transition the state as part of handling the EndTxnRequest if (!isEpochBump) { transitionTo(State.INITIALIZING); log.info("Invoking InitProducerId for the first time in order to acquire a producer ID"); } else { log.info("Invoking InitProducerId with current producer ID and epoch {} in order to bump the epoch", producerIdAndEpoch); } InitProducerIdRequestData requestData = new InitProducerIdRequestData() .setTransactionalId(transactionalId) .setTransactionTimeoutMs(transactionTimeoutMs) .setProducerId(producerIdAndEpoch.producerId) .setProducerEpoch(producerIdAndEpoch.epoch); InitProducerIdHandler handler = new InitProducerIdHandler(new InitProducerIdRequest.Builder(requestData), isEpochBump); enqueueRequest(handler); return handler.result; }, State.INITIALIZING); } On Wed, Jun 2, 2021 at 3:55 PM Piotr Nowojski <[hidden email]> wrote:
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Thanks for the update. Skimming over the code it looks indeed that we are overwriting the values of the static value ProducerIdAndEpoch.NONE. I am not 100% how this will cause the observed problem, though. I am also not a Flink Kafka connector and Kafka expert so I would appreciate it if someone more familiar could double check this part of the code. Concerning the required changing of the UID of an operator Piotr, is this a known issue and documented somewhere? I find this rather surprising from a user's point of view. Cheers, Till On Thu, Jun 3, 2021 at 8:53 AM Till Rohrmann <[hidden email]> wrote:
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I encountered the exact same issue before when experimenting in a testing environment. I was not able to spot the bug as mentioned in this thread, the solution I did was to downgrade my own kafka-client version from 2.5 to 2.4.1, matching the version of flink-connector-kafka. In 2.4.1 Kafka, TransactionManager is initializing producerIdAndEpoch using this.producerIdAndEpoch = new ProducerIdAndEpoch(NO_PRODUCER_ID, NO_PRODUCER_EPOCH); instead of this.producerIdAndEpoch = ProducerIdAndEpoch.NONE; On Thu, Jun 3, 2021 at 12:11 AM Till Rohrmann <[hidden email]> wrote:
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Thanks for this insight. So the problem might be Flink using an internal Kafka API (the connector uses reflection to get hold of the TransactionManager) which changed between version 2.4.1 and 2.5. I think this is a serious problem because it breaks our end-to-end exactly once story when using new Kafka versions. Cheers, Till On Thu, Jun 3, 2021 at 10:17 AM Tianxin Zhao <[hidden email]> wrote:
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Hi, Thanks Tianxin and 周瑞' for reporting and tracking down the problem. Indeed that could be the reason behind it. Have either of you already created a JIRA ticket for this bug? > Concerning the required changing of the UID of an operator Piotr, is this a known issue and documented somewhere? I find this rather surprising from a user's point of view. You don't need to change UID, you just need to make sure that the transactional.ids are unique, either via UID or the task name. It's not documented, and spawning a new job from an old one, while keeping both of them running is not officially supported. In order to officially support this scenario, Flink would need to have a better support of stop-with-savepoint (commit pending transactions, without starting new transactions for new records - that would require us to extend PublicAPI). `setLogFailuresOnly` has a purpose of recovering from some critical/fatal otherwise failures, for example if transactions have timed out. It's a lucky conicindence that it can be leveraged in this scenario.. Best, Piotrek czw., 3 cze 2021 o 11:43 Till Rohrmann <[hidden email]> napisał(a):
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