zhuzhurk commented on code in PR #24415: URL: https://github.com/apache/flink/pull/24415#discussion_r1538868578
########## flink-core/src/main/java/org/apache/flink/api/connector/source/SupportsBatchSnapshot.java: ########## @@ -0,0 +1,30 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.api.connector.source; + +import org.apache.flink.annotation.PublicEvolving; + +/** + * An identifier interface for {@link SplitEnumerator}, which is used to support taking snapshot in + * no-checkpoint/batch scenarios (for example to support job recovery in batch jobs). Once a {@link + * SplitEnumerator} implements this interface, its {@link SplitEnumerator#snapshotState} method + * needs to accept -1 (NO_CHECKPOINT) as the argument. + */ +@PublicEvolving +public interface SupportsBatchSnapshot {} Review Comment: -> A decorative interface {@link SplitEnumerator}. Implementing it means the split enumerator {@link SplitEnumerator#snapshotState} method supports taking snapshot in batch processing scenarios. In such scenarios, the checkpointId will always be -1. I think `-1` does not mean `no-checkpoint` in this case. ########## flink-runtime/src/main/java/org/apache/flink/runtime/operators/coordination/OperatorCoordinatorHolder.java: ########## @@ -437,9 +437,8 @@ private void setupSubtaskGateway(final SubtaskAccess sta) { final SubtaskGatewayImpl gateway = new SubtaskGatewayImpl(sta, mainThreadExecutor, unconfirmedEvents); - // When concurrent execution attempts is supported, the checkpoint must have been disabled. - // Thus, we don't need to maintain subtaskGatewayMap - if (!context.isConcurrentExecutionAttemptsSupported()) { + // We don't need to maintain subtaskGatewayMap when checkpoint coordinator is null. + if (context.getCheckpointCoordinator() != null) { subtaskGatewayMap.put(gateway.getSubtask(), gateway); Review Comment: The comments of the field `subtaskGatewayMap` is not updated. ########## flink-runtime/src/main/java/org/apache/flink/runtime/operators/coordination/RecreateOnResetOperatorCoordinator.java: ########## @@ -160,6 +160,17 @@ public void resetToCheckpoint(final long checkpointId, @Nullable final byte[] ch }); } + @Override + public boolean supportsBatchSnapshot() { + try { + return getInternalCoordinator().supportsBatchSnapshot(); + } catch (Exception e) { + String msg = "Could not get internal coordinator"; + LOG.error(msg, e); + throw new RuntimeException(msg, e); + } Review Comment: `getInternalCoordinator()` can be heavy and block the main thread. Given that this method should not trigger any actions on the coordinator, maybe we can directly check `coordinator.internalCoordinator` that it is not null and invoke `internalCoordinator.supportsBatchSnapshot()`. ########## flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SourceCoordinatorSerdeUtils.java: ########## @@ -53,4 +62,62 @@ static byte[] readBytes(DataInputStream in, int size) throws IOException { in.readFully(bytes); return bytes; } + + /** Serialize the assignment by checkpoint ids. */ + static <SplitT> byte[] writeAssignments( + Map<Integer, LinkedHashSet<SplitT>> assignments, + SimpleVersionedSerializer<SplitT> splitSerializer) + throws IOException { + try (ByteArrayOutputStream baos = new ByteArrayOutputStream(); + DataOutputStream out = new DataOutputViewStreamWrapper(baos)) { + // SplitSerializer version. Review Comment: useless comment ########## flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SplitAssignmentTracker.java: ########## @@ -65,6 +69,33 @@ public void onCheckpoint(long checkpointId) throws Exception { uncheckpointedAssignments = new HashMap<>(); } + /** + * Take a snapshot of the split assignments. + * + * @param checkpointId the id of the ongoing checkpoint + */ + public byte[] snapshotState( + long checkpointId, SimpleVersionedSerializer<SplitT> splitSerializer) throws Exception { + checkState(checkpointId == NO_CHECKPOINT); + return SourceCoordinatorSerdeUtils.writeAssignments( + uncheckpointedAssignments, splitSerializer); + } + + /** + * Restore the state of the SplitAssignmentTracker. + * + * @param splitSerializer The serializer of the splits. + * @param assignmentData The state of the SplitAssignmentTracker. + * @throws Exception when the state deserialization fails. + */ + public void restoreState( + SimpleVersionedSerializer<SplitT> splitSerializer, byte[] assignmentData) + throws Exception { + // Read the split assignments by checkpoint id. Review Comment: The comment is outdated. ########## flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SourceCoordinatorSerdeUtils.java: ########## @@ -53,4 +62,62 @@ static byte[] readBytes(DataInputStream in, int size) throws IOException { in.readFully(bytes); return bytes; } + + /** Serialize the assignment by checkpoint ids. */ Review Comment: The comment is outdated. ########## flink-runtime/src/main/java/org/apache/flink/runtime/operators/coordination/OperatorCoordinator.java: ########## @@ -234,6 +234,16 @@ default void notifyCheckpointAborted(long checkpointId) {} */ void executionAttemptReady(int subtask, int attemptNumber, SubtaskGateway gateway); + /** + * Whether the operator coordinator supports taking snapshot in no-checkpoint/batch scenarios. + * If it returns true, it's {@link OperatorCoordinator#checkpointCoordinator} and {@link + * OperatorCoordinator#resetToCheckpoint} methods need to accept {@link + * OperatorCoordinator#NO_CHECKPOINT} as the value of checkpoint id. Otherwise, returns false. + */ + default boolean supportsBatchSnapshot() { Review Comment: -> Whether the operator coordinator supports taking snapshot in no-checkpoint/batch scenarios. If it returns true, the {@link OperatorCoordinator#checkpointCoordinator} and {@link OperatorCoordinator#resetToCheckpoint} methods supports taking snapshot and restoring from a snapshot in batch processing scenarios. In such scenarios, the checkpointId will always be -1. ########## flink-runtime/src/main/java/org/apache/flink/runtime/operators/coordination/OperatorCoordinatorHolder.java: ########## @@ -314,7 +314,8 @@ private void checkpointCoordinatorInternal( (success, failure) -> { if (failure != null) { result.completeExceptionally(failure); - } else if (closeGateways(checkpointId)) { + } else if (checkpointId == OperatorCoordinator.NO_CHECKPOINT Review Comment: It's a bit weird to say `NO_CHECKPOINT` and the description of it is not right in batch scenarios. I prefer to introduce a new const `OperatorCoordinator.BATCH_CHECKPOINT_ID` which is also -1. ########## flink-runtime/src/test/java/org/apache/flink/runtime/operators/coordination/OperatorCoordinatorHolderTest.java: ########## @@ -574,8 +574,7 @@ public boolean hasFinishedTasks() { }, IteratorChain::new, false), - new CheckpointStatsTracker( - 1, new WatermarkStrategyTest.DummyMetricGroup(), jobId))); + new CheckpointStatsTracker(1, new UnregisteredMetricsGroup(), jobId))); Review Comment: This change looks good to me. Just wondering what would happen without this change? ########## flink-runtime/src/main/java/org/apache/flink/runtime/operators/coordination/SubtaskGatewayImpl.java: ########## @@ -185,11 +185,6 @@ void markForCheckpoint(long checkpointId) { if (checkpointId > latestAttemptedCheckpointId) { currentMarkedCheckpointIds.add(checkpointId); latestAttemptedCheckpointId = checkpointId; - } else { Review Comment: Maybe `else if (checkpointId != BATCH_CHECKPOINT_ID)` ########## flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SourceCoordinatorSerdeUtils.java: ########## @@ -53,4 +62,62 @@ static byte[] readBytes(DataInputStream in, int size) throws IOException { in.readFully(bytes); return bytes; } + + /** Serialize the assignment by checkpoint ids. */ + static <SplitT> byte[] writeAssignments( Review Comment: I prefer to name the two methods as `serializeAssignments` and `deserializeAssignments`. ########## flink-runtime/src/main/java/org/apache/flink/runtime/source/coordinator/SplitAssignmentTracker.java: ########## @@ -65,6 +69,33 @@ public void onCheckpoint(long checkpointId) throws Exception { uncheckpointedAssignments = new HashMap<>(); } + /** + * Take a snapshot of the split assignments. + * + * @param checkpointId the id of the ongoing checkpoint + */ + public byte[] snapshotState( + long checkpointId, SimpleVersionedSerializer<SplitT> splitSerializer) throws Exception { + checkState(checkpointId == NO_CHECKPOINT); Review Comment: Looks to me the `checkpointId` param is not needed. ########## flink-runtime/src/test/java/org/apache/flink/runtime/source/coordinator/SplitAssignmentTrackerTest.java: ########## @@ -108,15 +105,15 @@ public void testOnCheckpointComplete() throws Exception { // Complete the first checkpoint. tracker.onCheckpointComplete(checkpointId1); - assertNull(tracker.assignmentsByCheckpointId(checkpointId1)); + assertThat(tracker.assignmentsByCheckpointId(checkpointId1)).isNull(); verifyAssignment( Arrays.asList("3"), tracker.assignmentsByCheckpointId(checkpointId2).get(0)); verifyAssignment( Arrays.asList("4", "5"), tracker.assignmentsByCheckpointId(checkpointId2).get(1)); } @Test - public void testGetAndRemoveUncheckpointedAssignment() throws Exception { + void testGetAndRemoveUncheckpointedAssignment() throws Exception { Review Comment: There is one more test case below which is not fixed. -- This is an automated message from the Apache Git Service. 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