Fix restart aggregation when remote partitions are already completed

spring-batch-core/src/main/java/org/springframework/batch/core/partition/support/AbstractPartitionHandler.java

@@ -18,9 +18,11 @@
 import java.util.Collection;
 import java.util.Set;
 
+import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.step.StepExecution;
 import org.springframework.batch.core.partition.PartitionHandler;
 import org.springframework.batch.core.partition.StepExecutionSplitter;
+import org.springframework.util.CollectionUtils;
 
 /**
  * Base {@link PartitionHandler} implementation providing common base features. Subclasses
@@ -55,8 +57,25 @@ protected abstract Set<StepExecution> doHandle(StepExecution managerStepExecutio
 	public Collection<StepExecution> handle(StepExecutionSplitter stepSplitter,
 			final StepExecution managerStepExecution) throws Exception {
 		final Set<StepExecution> stepExecutions = stepSplitter.split(managerStepExecution, gridSize);
+		final Set<StepExecution> alreadyCompleted = CollectionUtils.newHashSet(stepExecutions.size());
+		final Set<StepExecution> toBeExecuted = CollectionUtils.newHashSet(stepExecutions.size());
 
-		return doHandle(managerStepExecution, stepExecutions);
+		for (StepExecution stepExecution : stepExecutions) {
+			if (stepExecution.getStatus() == BatchStatus.COMPLETED) {
+				alreadyCompleted.add(stepExecution);
+			}
+			else {
+				toBeExecuted.add(stepExecution);
+			}
+		}
+
+		final Set<StepExecution> updatedExecutions = CollectionUtils.newHashSet(stepExecutions.size());
+		final Set<StepExecution> handledExecutions = doHandle(managerStepExecution, toBeExecuted);
+		if (handledExecutions != null) {
+			updatedExecutions.addAll(handledExecutions);
+		}
+		updatedExecutions.addAll(alreadyCompleted);
+		return updatedExecutions;
 	}
 
 	/**

spring-batch-core/src/main/java/org/springframework/batch/core/partition/support/SimpleStepExecutionSplitter.java

@@ -143,8 +143,13 @@ public Set<StepExecution> split(StepExecution stepExecution, int gridSize) throw
 				set.add(currentStepExecution);
 			}
 			else { // restart
-				if (lastStepExecution.getStatus() != BatchStatus.COMPLETED
-						&& shouldStart(allowStartIfComplete, stepExecution, lastStepExecution)) {
+				if (lastStepExecution.getStatus() == BatchStatus.COMPLETED) {
+					// Keep completed partitions for aggregation on restart.
+					if (!isSameJobExecution(stepExecution, lastStepExecution)) {
+						set.add(lastStepExecution);
+					}
+				}
+				else if (shouldStart(allowStartIfComplete, stepExecution, lastStepExecution)) {
 					StepExecution currentStepExecution = jobRepository.createStepExecution(stepName, jobExecution);
 					currentStepExecution.setExecutionContext(lastStepExecution.getExecutionContext());
 					jobRepository.updateExecutionContext(currentStepExecution);

spring-batch-core/src/test/java/org/springframework/batch/core/partition/PartitionStepTests.java

@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -245,4 +246,55 @@ public void aggregate(StepExecution result, Collection<StepExecution> executions
 		assertEquals(true, stepExecution.getExecutionContext().get("aggregated"));
 	}
 
+	@Test
+	void testRestartWhenAllPartitionsCompletedShouldAggregateCompletedPartitions() throws Exception {
+		AtomicInteger aggregateSizeOnRestart = new AtomicInteger(-1);
+		AtomicBoolean firstAggregation = new AtomicBoolean(true);
+		step.setStepExecutionAggregator((result, executions) -> {
+			if (firstAggregation.getAndSet(false)) {
+				return;
+			}
+			aggregateSizeOnRestart.set(executions.size());
+		});
+
+		SimpleStepExecutionSplitter stepExecutionSplitter = new SimpleStepExecutionSplitter(jobRepository,
+				step.getName(), new SimplePartitioner());
+		step.setStepExecutionSplitter(stepExecutionSplitter);
+		step.setPartitionHandler((stepSplitter, managerExecution) -> {
+			Set<StepExecution> executions = stepSplitter.split(managerExecution, 2);
+			for (StepExecution execution : executions) {
+				if (execution.getStatus() != BatchStatus.COMPLETED) {
+					execution.setStatus(BatchStatus.COMPLETED);
+					execution.setExitStatus(ExitStatus.COMPLETED);
+					jobRepository.update(execution);
+				}
+			}
+			return executions;
+		});
+
+		step.afterPropertiesSet();
+		JobParameters jobParameters = new JobParameters();
+		ExecutionContext executionContext = new ExecutionContext();
+		JobInstance jobInstance = jobRepository.createJobInstance("remotePartitionRestartJob", jobParameters);
+		JobExecution firstJobExecution = jobRepository.createJobExecution(jobInstance, jobParameters, executionContext);
+		StepExecution firstManagerStepExecution = jobRepository.createStepExecution("manager", firstJobExecution);
+		step.execute(firstManagerStepExecution);
+
+		firstManagerStepExecution.setStatus(BatchStatus.FAILED);
+		firstManagerStepExecution.setExitStatus(ExitStatus.FAILED);
+		jobRepository.update(firstManagerStepExecution);
+		firstJobExecution.setStatus(BatchStatus.FAILED);
+		firstJobExecution.setEndTime(LocalDateTime.now());
+		jobRepository.update(firstJobExecution);
+
+		JobExecution restartedJobExecution = jobRepository.createJobExecution(jobInstance, jobParameters,
+				executionContext);
+		StepExecution restartedManagerStepExecution = jobRepository.createStepExecution("manager",
+				restartedJobExecution);
+		step.execute(restartedManagerStepExecution);
+
+		assertEquals(BatchStatus.COMPLETED, restartedManagerStepExecution.getStatus());
+		assertEquals(2, aggregateSizeOnRestart.get());
+	}
+
 }

spring-batch-core/src/test/java/org/springframework/batch/core/partition/support/SimpleStepExecutionSplitterTests.java

@@ -119,6 +119,19 @@ void testRememberGridSize() throws Exception {
 		assertEquals(2, provider.split(stepExecution, 3).size());
 	}
 
+	@Test
+	void testCompletedPartitionsAreReturnedForAggregationOnRestart() throws Exception {
+		SimpleStepExecutionSplitter provider = new SimpleStepExecutionSplitter(jobRepository, step.getName(),
+				new SimplePartitioner());
+		Set<StepExecution> split = provider.split(stepExecution, 2);
+		assertEquals(2, split.size());
+		stepExecution = update(split, stepExecution, BatchStatus.COMPLETED, false);
+
+		Set<StepExecution> restartSplit = provider.split(stepExecution, 2);
+		assertEquals(2, restartSplit.size());
+		assertTrue(restartSplit.stream().allMatch(execution -> execution.getStatus() == BatchStatus.COMPLETED));
+	}
+
 	@Test
 	void testRememberPartitionNames() throws Exception {
 		class CustomPartitioner implements Partitioner, PartitionNameProvider {

spring-batch-core/src/test/java/org/springframework/batch/core/partition/support/TaskExecutorPartitionHandlerTests.java

@@ -26,6 +26,7 @@
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.ExitStatus;
 import org.springframework.batch.core.job.JobExecution;
 import org.springframework.batch.core.job.JobExecutionException;
@@ -128,4 +129,31 @@ void testTaskExecutorFailure() throws Exception {
 		assertEquals(ExitStatus.FAILED.getExitCode(), stepExecution.getExitStatus().getExitCode());
 	}
 
+	@Test
+	void testCompletedStepExecutionsAreNotReExecutedButReturned() throws Exception {
+		StepExecutionSplitter splitter = new StepExecutionSplitter() {
+			@Override
+			public String getStepName() {
+				return stepExecution.getStepName();
+			}
+
+			@Override
+			public Set<StepExecution> split(StepExecution managerStepExecution, int gridSize) {
+				Set<StepExecution> split = new HashSet<>();
+				StepExecution completed = new StepExecution(10L, "completed", managerStepExecution.getJobExecution());
+				completed.setStatus(BatchStatus.COMPLETED);
+				completed.setExitStatus(ExitStatus.COMPLETED);
+				split.add(completed);
+				split.add(new StepExecution(11L, "started", managerStepExecution.getJobExecution()));
+				return split;
+			}
+		};
+
+		Collection<StepExecution> executions = handler.handle(splitter, stepExecution);
+
+		assertEquals(1, count);
+		assertEquals("[started]", stepExecutions.toString());
+		assertEquals(2, executions.size());
+	}
+
 }