[HUDI-2901] Fixed the bug clustering jobs cannot running in parallel (#4178)

hudi-common/src/main/java/org/apache/hudi/common/util/FutureUtils.java

@@ -0,0 +1,46 @@
+/*
+ * 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.hudi.common.util;
+
+import javax.annotation.Nonnull;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
+
+/**
+ * A utility class for future operation.
+ */
+public class FutureUtils {
+
+  /**
+   * Parallel CompletableFutures
+   *
+   * @param futures CompletableFuture list
+   * @return a new CompletableFuture which will completed when all of the given CompletableFutures complete.
+   */
+  public static <T> CompletableFuture<List<T>> allOf(@Nonnull List<CompletableFuture<T>> futures) {
+    return CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]))
+        .thenApply(aVoid ->
+            futures.stream()
+                // NOTE: This join wouldn't block, since all the
+                //       futures are completed at this point.
+                .map(CompletableFuture::join)
+                .collect(Collectors.toList()));
+  }
+}