Source:
public TaskAcknowledgeResult acknowledgeTask( ExecutionAttemptID executionAttemptId, TaskStateSnapshot operatorSubtaskStates, CheckpointMetrics metrics) { synchronized (lock) { if (discarded) { return TaskAcknowledgeResult.DISCARDED; } final ExecutionVertex vertex = notYetAcknowledgedTasks.remove(executionAttemptId); if (vertex == null) { if (acknowledgedTasks.contains(executionAttemptId)) { return TaskAcknowledgeResult.DUPLICATE; } else { return TaskAcknowledgeResult.UNKNOWN; } } else { acknowledgedTasks.add(executionAttemptId); } List<OperatorID> operatorIDs = vertex.getJobVertex().getOperatorIdPairList().getOperatorIds(); int subtaskIndex = vertex.getParallelSubtaskIndex(); long ackTimestamp = System.currentTimeMillis(); long stateSize = 0L; if (operatorSubtaskStates != null) { for (OperatorID operatorID : operatorIDs) { OperatorSubtaskState operatorSubtaskState = operatorSubtaskStates.getSubtaskStateByOperatorID(operatorID); if (operatorSubtaskState == null) { operatorSubtaskState = new OperatorSubtaskState(); } OperatorState operatorState = operatorStates.get(operatorID); if (operatorState == null) { operatorState = new OperatorState( operatorID, vertex.getTotalNumberOfParallelSubtasks(), vertex.getMaxParallelism()); operatorStates.put(operatorID, operatorState); } operatorState.putState(subtaskIndex, operatorSubtaskState); stateSize += operatorSubtaskState.getStateSize(); } } ++numAcknowledgedTasks; final PendingCheckpointStats statsCallback = this.statsCallback; if (statsCallback != null) { long alignmentDurationMillis = metrics.getAlignmentDurationNanos() / 1_000_000; long checkpointStartDelayMillis = metrics.getCheckpointStartDelayNanos() / 1_000_000; SubtaskStateStats subtaskStateStats = new SubtaskStateStats( subtaskIndex, ackTimestamp, stateSize, metrics.getSyncDurationMillis(), metrics.getAsyncDurationMillis(), alignmentDurationMillis, checkpointStartDelayMillis); statsCallback.reportSubtaskStats(vertex.getJobvertexId(), subtaskStateStats); } return TaskAcknowledgeResult.SUCCESS; } }

Target:
public TaskAcknowledgeResult acknowledgeTask( ExecutionAttemptID executionAttemptId, TaskStateSnapshot operatorSubtaskStates, CheckpointMetrics metrics) { synchronized (lock) { if (discarded) { return TaskAcknowledgeResult.DISCARDED; } final ExecutionVertex vertex = notYetAcknowledgedTasks.remove(executionAttemptId); if (vertex == null) { if (acknowledgedTasks.contains(executionAttemptId)) { return TaskAcknowledgeResult.DUPLICATE; } else { return TaskAcknowledgeResult.UNKNOWN; } } else { acknowledgedTasks.add(executionAttemptId); } List<OperatorIDPair> operatorIDs = vertex.getJobVertex().getOperatorIDs(); int subtaskIndex = vertex.getParallelSubtaskIndex(); long ackTimestamp = System.currentTimeMillis(); long stateSize = 0L; if (operatorSubtaskStates != null) { for (OperatorIDPair operatorID : operatorIDs) { OperatorSubtaskState operatorSubtaskState = operatorSubtaskStates.getSubtaskStateByOperatorID(operatorID.getGeneratedOperatorID()); if (operatorSubtaskState == null) { operatorSubtaskState = new OperatorSubtaskState(); } OperatorState operatorState = operatorStates.get(operatorID.getGeneratedOperatorID()); if (operatorState == null) { operatorState = new OperatorState( operatorID.getGeneratedOperatorID(), vertex.getTotalNumberOfParallelSubtasks(), vertex.getMaxParallelism()); operatorStates.put(operatorID.getGeneratedOperatorID(), operatorState); } operatorState.putState(subtaskIndex, operatorSubtaskState); stateSize += operatorSubtaskState.getStateSize(); } } ++numAcknowledgedTasks; final PendingCheckpointStats statsCallback = this.statsCallback; if (statsCallback != null) { long alignmentDurationMillis = metrics.getAlignmentDurationNanos() / 1_000_000; long checkpointStartDelayMillis = metrics.getCheckpointStartDelayNanos() / 1_000_000; SubtaskStateStats subtaskStateStats = new SubtaskStateStats( subtaskIndex, ackTimestamp, stateSize, metrics.getSyncDurationMillis(), metrics.getAsyncDurationMillis(), alignmentDurationMillis, checkpointStartDelayMillis); statsCallback.reportSubtaskStats(vertex.getJobvertexId(), subtaskStateStats); } return TaskAcknowledgeResult.SUCCESS; } }