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Merged
merged 3 commits into from
Jun 17, 2025
Merged

Optimize ParallelExecutor #2767

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6093589
Optimize ParallelExecutor
brfrn169 Jun 14, 2025
5c87a11
Merge branch 'master' into optimize-ParallelExecutor
feeblefakie Jun 17, 2025
95a8f22
Merge branch 'master' into optimize-ParallelExecutor
brfrn169 Jun 17, 2025
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7 changes: 7 additions & 0 deletions core/src/main/java/com/scalar/db/transaction/consensuscommit/ParallelExecutor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -155,6 +155,13 @@ private void executeTasks(
String taskName,
String transactionId)
throws ExecutionException, ValidationConflictException, CrudException {
if (tasks.size() == 1 && !noWait) {
// If there is only one task and noWait is false, we can run it directly without parallel
// execution.
executeTasksSerially(tasks, stopOnError, taskName, transactionId);
return;
}

if (parallel) {
executeTasksInParallel(tasks, noWait, stopOnError, taskName, transactionId);
} else {
Expand Down
111 changes: 111 additions & 0 deletions core/src/test/java/com/scalar/db/transaction/consensuscommit/ParallelExecutorTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import com.scalar.db.exception.transaction.ValidationConflictException;
import com.scalar.db.transaction.consensuscommit.ParallelExecutor.ParallelExecutorTask;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
Expand Down Expand Up @@ -100,6 +101,23 @@ public void prepare_ParallelPreparationEnabled_ShouldExecuteTasksInParallel()
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void prepare_ParallelPreparationEnabled_SingleTaskGiven_ShouldExecuteTasksSerially()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelPreparationEnabled()).thenReturn(true);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.prepare(tasks, TX_ID);

// Assert
verify(task, times(tasks.size())).run();
verify(parallelExecutorService, never()).execute(any());
}

@Test
public void
prepare_ParallelPreparationEnabled_ExecutionExceptionThrownByTask_ShouldNotStopRunningTasks()
Expand Down Expand Up @@ -176,6 +194,23 @@ public void validate_ParallelValidationEnabled_ShouldExecuteTasksInParallel()
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void validate_ParallelValidationEnabled_SingleTaskGiven_ShouldExecuteTasksSerially()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelValidationEnabled()).thenReturn(true);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.validate(tasks, TX_ID);

// Assert
verify(task, times(tasks.size())).run();
verify(parallelExecutorService, never()).execute(any());
}

@Test
public void
validate_ParallelValidationEnabled_ExecutionExceptionThrownByTask_ShouldStopRunningTasks()
Expand Down Expand Up @@ -254,6 +289,25 @@ public void commitRecords_ParallelCommitNotEnabled_ShouldExecuteTasksSerially()
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
commitRecords_ParallelCommitEnabledAndAsyncCommitNotEnabled_SingleTaskGiven_ShouldExecuteTasksSerially()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelCommitEnabled()).thenReturn(true);
when(config.isAsyncCommitEnabled()).thenReturn(false);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.commitRecords(tasks, TX_ID);

// Assert
verify(task, times(tasks.size())).run();
verify(parallelExecutorService, never()).execute(any());
}

@Test
public void
commitRecords_ParallelCommitEnabledAndAsyncCommitNotEnabled_ExecutionExceptionThrownByTask_ShouldNotStopRunningTasks()
Expand Down Expand Up @@ -287,6 +341,25 @@ public void commitRecords_ParallelCommitNotEnabled_ShouldExecuteTasksSerially()
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
commitRecords_ParallelCommitEnabledAndAsyncCommitEnabled_SingleTaskGiven_ShouldExecuteTasksInParallelAndAsynchronously()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelCommitEnabled()).thenReturn(true);
when(config.isAsyncCommitEnabled()).thenReturn(true);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.commitRecords(tasks, TX_ID);

// Assert
verify(task, atMost(tasks.size())).run();
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Copilot AI Jun 14, 2025

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Using atMost(tasks.size()) allows zero invocations, so the test could pass even if task.run() was never called. Consider using verify(task, atLeastOnce()).run() or verify(task, timeout(...).times(1)).run() to ensure it actually executes.

Suggested change
verify(task, atMost(tasks.size())).run();
verify(task, atLeastOnce()).run();

Copilot uses AI. Check for mistakes.
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
commitRecords_ParallelCommitEnabledAndAsyncCommitEnabled_ExecutionExceptionThrownByTask_ShouldNotStopRunningTasks()
Expand Down Expand Up @@ -349,6 +422,25 @@ public void rollbackRecords_ParallelRollbackNotEnabled_ShouldExecuteTasksSeriall
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
rollbackRecords_ParallelRollbackEnabledAndAsyncRollbackNotEnabled_SingleTaskGiven_ShouldExecuteTasksSerially()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelRollbackEnabled()).thenReturn(true);
when(config.isAsyncRollbackEnabled()).thenReturn(false);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.rollbackRecords(tasks, TX_ID);

// Assert
verify(task, times(tasks.size())).run();
verify(parallelExecutorService, never()).execute(any());
}

@Test
public void
rollbackRecords_ParallelRollbackEnabledAndAsyncRollbackNotEnabled_ExecutionExceptionThrownByTask_ShouldNotStopRunningTasks()
Expand Down Expand Up @@ -382,6 +474,25 @@ public void rollbackRecords_ParallelRollbackNotEnabled_ShouldExecuteTasksSeriall
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
rollbackRecords_ParallelRollbackEnabledAndAsyncRollbackEnabled_SingleTaskGiven_ShouldExecuteTasksInParallelAndAsynchronously()
throws ExecutionException, ValidationConflictException, CrudException {
// Arrange
when(config.isParallelRollbackEnabled()).thenReturn(true);
when(config.isAsyncRollbackEnabled()).thenReturn(true);

// A single task
tasks = Collections.singletonList(task);

// Act
parallelExecutor.rollbackRecords(tasks, TX_ID);

// Assert
verify(task, atMost(tasks.size())).run();
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Copilot AI Jun 14, 2025

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As above, atMost(tasks.size()) could allow zero runs. For the asynchronous rollback test, use atLeastOnce() or a timeout-based verification to confirm the task actually executes.

Suggested change
verify(task, atMost(tasks.size())).run();
verify(task, atLeastOnce()).run();

Copilot uses AI. Check for mistakes.
verify(parallelExecutorService, times(tasks.size())).execute(any());
}

@Test
public void
rollbackRecords_ParallelRollbackEnabledAndAsyncRollbackEnabled_ExecutionExceptionThrownByTask_ShouldNotStopRunningTasks()
Expand Down