[Dataflow Streaming] [Multi Key] Introduce KeyGroupWorkQueue and integrate with BoundedQueueExecutor

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java

@@ -178,6 +178,9 @@ public final class StreamingDataflowWorker {
   // Experiment make the monitor within BoundedQueueExecutor fair
   public static final String BOUNDED_QUEUE_EXECUTOR_USE_FAIR_MONITOR_EXPERIMENT =
       "windmill_bounded_queue_executor_use_fair_monitor";
+  // Don't use. Experiment guarding multi key bundles. The feature is work in progress and
+  // incomplete.
+  private static final String UNSTABLE_ENABLE_MULTI_KEY_BUNDLE = "unstable_enable_multi_key_bundle";
 
   private final WindmillStateCache stateCache;
   private AtomicReference<StreamingWorkerStatusPages> statusPages = new AtomicReference<>();
@@ -1017,14 +1020,17 @@ private static JobHeader createJobHeader(DataflowWorkerHarnessOptions options, l
   private static BoundedQueueExecutor createWorkUnitExecutor(DataflowWorkerHarnessOptions options) {
     boolean useFairMonitor =
         DataflowRunner.hasExperiment(options, BOUNDED_QUEUE_EXECUTOR_USE_FAIR_MONITOR_EXPERIMENT);
+    boolean useKeyGroupWorkQueue =
+        DataflowRunner.hasExperiment(options, UNSTABLE_ENABLE_MULTI_KEY_BUNDLE);
     return new BoundedQueueExecutor(
         chooseMaxThreads(options),
         THREAD_EXPIRATION_TIME_SEC,
         TimeUnit.SECONDS,
         chooseMaxBundlesOutstanding(options),
         chooseMaxBytesOutstanding(options),
         new ThreadFactoryBuilder().setNameFormat("DataflowWorkUnits-%d").setDaemon(true).build(),
-        useFairMonitor);
+        useFairMonitor,
+        useKeyGroupWorkQueue);
   }
 
   public static void main(String[] args) throws Exception {

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/streaming/ExecutableWork.java

@@ -62,16 +62,24 @@ public void run(BoundedQueueExecutorWorkHandle handle) {
     }
   }
 
-  public final WorkId id() {
+  public WorkId id() {
     return work().id();
   }
 
-  public final Windmill.WorkItem getWorkItem() {
+  public Windmill.WorkItem getWorkItem() {
     return work().getWorkItem();
   }
 
   @Override
   public String toString() {
     return "ExecutableWork{" + id() + "}";
   }
+
+  public String getComputationId() {
+    return work().getComputationId();
+  }
+
+  public Work.KeyGroup getKeyGroup() {
+    return work().getKeyGroup();
+  }
 }

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/streaming/Work.java

@@ -25,6 +25,7 @@
 import java.util.IntSummaryStatistics;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -52,6 +53,7 @@
 import org.apache.beam.sdk.annotations.Internal;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.joda.time.Duration;
 import org.joda.time.Instant;
 
@@ -74,6 +76,7 @@ public final class Work implements RefreshableWork {
   private final Instant startTime;
   private final Map<LatencyAttribution.State, Duration> totalDurationPerState;
   private final WorkId id;
+  private final KeyGroup keyGroup;
   private final String latencyTrackingId;
   private final long serializedWorkItemSize;
   private volatile TimedState currentState;
@@ -101,6 +104,10 @@ private Work(
     // keyUniverse inside EnumMap every time.
     this.totalDurationPerState = new EnumMap<>(EMPTY_ENUM_MAP);
     this.id = WorkId.of(workItem);
+    this.keyGroup =
+        workItem.hasKeyGroup()
+            ? KeyGroup.create(workItem.getKeyGroup().getHigh(), workItem.getKeyGroup().getLow())
+            : KeyGroup.DEFAULT;
     this.latencyTrackingId =
         Long.toHexString(workItem.getShardingKey())
             + '-'
@@ -383,6 +390,14 @@ private boolean isCommitPending() {
     abstract Instant startTime();
   }
 
+  public String getComputationId() {
+    return processingContext.computationId();
+  }
+
+  public KeyGroup getKeyGroup() {
+    return keyGroup;
+  }
+
   @AutoValue
   public abstract static class ProcessingContext {
 
@@ -416,4 +431,60 @@ private Optional<KeyedGetDataResponse> fetchKeyedState(KeyedGetDataRequest reque
       return Optional.ofNullable(getDataClient().getStateData(computationId(), request));
     }
   }
+
+  /**
+   * WorkItems with same key group and computation are eligible to be executed together in a
+   * multi-key bundle.
+   */
+  public static final class KeyGroup {
+
+    // Work items equaling to the default keyGroup will always be executed
+    // separately and not in a multi-key bundle
+    public static final KeyGroup DEFAULT = new KeyGroup(0, 0);
+
+    private final long high;
+    private final long low;
+
+    private KeyGroup(long high, long low) {
+      this.high = high;
+      this.low = low;
+    }
+
+    public static KeyGroup create(long high, long low) {
+      if (high == 0 && low == 0) {
+        return DEFAULT;
+      }
+      return new KeyGroup(high, low);
+    }
+
+    public long high() {
+      return high;
+    }
+
+    public long low() {
+      return low;
+    }
+
+    @Override
+    public boolean equals(@Nullable Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (!(o instanceof KeyGroup)) {
+        return false;
+      }
+      KeyGroup other = (KeyGroup) o;
+      return high == other.high && low == other.low;
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(high, low);
+    }
+
+    @Override
+    public String toString() {
+      return String.format("%016x%016x", high, low);
+    }
+  }
 }

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/util/BoundedQueueExecutor.java

@@ -29,10 +29,13 @@
 import javax.annotation.concurrent.GuardedBy;
 import org.apache.beam.runners.dataflow.worker.streaming.BoundedQueueExecutorWorkHandle;
 import org.apache.beam.runners.dataflow.worker.streaming.ExecutableWork;
+import org.apache.beam.runners.dataflow.worker.streaming.Work;
+import org.apache.beam.runners.dataflow.worker.streaming.Work.KeyGroup;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.Monitor;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.Monitor.Guard;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An executor for executing work on windmill items. */
 @SuppressWarnings({
@@ -78,14 +81,19 @@ private static class Budget {
   @GuardedBy("this")
   private long totalTimeMaxActiveThreadsUsed;
 
+  // If set the keyGroupWorkQueue is used by the underlying executor.
+  private final @Nullable KeyGroupWorkQueue keyGroupWorkQueue;
+
   public BoundedQueueExecutor(
       int initialMaximumPoolSize,
       long keepAliveTime,
       TimeUnit unit,
       int maximumElementsOutstanding,
       long maximumBytesOutstanding,
       ThreadFactory threadFactory,
-      boolean useFairMonitor) {
+      boolean useFairMonitor,
+      boolean useKeyGroupWorkQueue) {
+    this.keyGroupWorkQueue = useKeyGroupWorkQueue ? new KeyGroupWorkQueue(useFairMonitor) : null;
     this.maximumPoolSize = initialMaximumPoolSize;
     monitor = new Monitor(useFairMonitor);
     executor =
@@ -94,7 +102,7 @@ public BoundedQueueExecutor(
             initialMaximumPoolSize,
             keepAliveTime,
             unit,
-            new LinkedBlockingQueue<>(),
+            keyGroupWorkQueue != null ? keyGroupWorkQueue : new LinkedBlockingQueue<>(),
             threadFactory) {
           @Override
           protected void beforeExecute(Thread t, Runnable r) {
@@ -313,7 +321,7 @@ public synchronized void close() {
     }
   }
 
-  private static final class QueuedWork implements Runnable {
+  static final class QueuedWork implements Runnable {
 
     private final ExecutableWork work;
     private final BoundedQueueExecutorWorkHandleImpl handle;
@@ -378,6 +386,22 @@ BoundedQueueExecutorWorkHandleImpl createBudgetHandle(int elements, long bytes)
     return new BoundedQueueExecutorWorkHandleImpl(elements, bytes);
   }
 
+  public @Nullable ExecutableWork pollWork(
+      String computationId, Work.KeyGroup keyGroup, BoundedQueueExecutorWorkHandle handle) {
+    checkArgument(handle instanceof BoundedQueueExecutorWorkHandleImpl);
+    checkArgument(computationId != null && keyGroup != null && !keyGroup.equals(KeyGroup.DEFAULT));
+    BoundedQueueExecutorWorkHandleImpl internalHandle = (BoundedQueueExecutorWorkHandleImpl) handle;
+    if (keyGroupWorkQueue == null) {
+      return null;
+    }
+    QueuedWork queuedWork = keyGroupWorkQueue.pollWork(computationId, keyGroup);
+    if (queuedWork == null) {
+      return null;
+    }
+    internalHandle.merge(queuedWork.getHandle());
+    return queuedWork.getWork();
+  }
+
   private void decrementCounters(int elements, long bytes) {
     // All threads queue decrements and one thread grabs the monitor and updates
     // counters. We do this to reduce contention on monitor which is locked by