diff --git a/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java b/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
index b418ddcc1..53243cb71 100644
--- a/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
@@ -179,7 +179,7 @@ public class CollStreamUtil {
 		Set<K> key = new HashSet<>();
 		key.addAll(map1.keySet());
 		key.addAll(map2.keySet());
-		Map<K, V> map = new HashMap<>();
+		Map<K, V> map = MapUtil.newHashMap(key.size());
 		for (K t : key) {
 			X x = map1.get(t);
 			Y y = map2.get(t);
diff --git a/hutool-core/src/main/java/cn/hutool/core/thread/SyncUtil.java b/hutool-core/src/main/java/cn/hutool/core/thread/SyncUtil.java
new file mode 100644
index 000000000..5f4601b39
--- /dev/null
+++ b/hutool-core/src/main/java/cn/hutool/core/thread/SyncUtil.java
@@ -0,0 +1,53 @@
+package cn.hutool.core.thread;
+
+import cn.hutool.core.exceptions.ExceptionUtil;
+
+import java.lang.reflect.UndeclaredThrowableException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+/**
+ * CompletableFuture工具类，叫CompletableFutureUtil太长
+ *
+ * @author <achao1441470436@gmail.com>
+ * @since 2021/11/10 0010 20:55
+ */
+public class SyncUtil {
+
+	private SyncUtil() {
+		/* Do not new me! */
+	}
+
+	/**
+	 * 等待所有任务执行完毕，包裹了异常
+	 *
+	 * @param tasks 并行任务
+	 * @throws UndeclaredThrowableException 未受检异常
+	 */
+	public static void wait(CompletableFuture<?>... tasks) {
+		try {
+			CompletableFuture.allOf(tasks).get();
+		} catch (InterruptedException | ExecutionException e) {
+			ExceptionUtil.wrapAndThrow(e);
+		}
+	}
+
+	/**
+	 * 获取异步任务结果，包裹了异常
+	 *
+	 * @param task 异步任务
+	 * @param <T>  任务返回值类型
+	 * @return 任务返回值
+	 * @throws RuntimeException 未受检异常
+	 */
+	public static <T> T get(CompletableFuture<T> task) {
+		RuntimeException exception;
+		try {
+			return task.get();
+		} catch (InterruptedException | ExecutionException e) {
+			exception = ExceptionUtil.wrapRuntime(e);
+		}
+		throw exception;
+	}
+
+}
diff --git a/hutool-core/src/main/java/cn/hutool/core/util/NumberUtil.java b/hutool-core/src/main/java/cn/hutool/core/util/NumberUtil.java
index 08f30132a..ec92e1a21 100644
--- a/hutool-core/src/main/java/cn/hutool/core/util/NumberUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/util/NumberUtil.java
@@ -1362,10 +1362,9 @@ public class NumberUtil {
 			throw new UtilException("Size is larger than range between begin and end!");
 		}
 
-		Random ran = new Random();
-		Set<Integer> set = new HashSet<>();
+		Set<Integer> set = new HashSet<>(Math.max((int) (size / .75f) + 1, 16));
 		while (set.size() < size) {
-			set.add(begin + ran.nextInt(end - begin));
+			set.add(begin + RandomUtil.randomInt(end - begin));
 		}
 
 		return set.toArray(new Integer[size]);
diff --git a/hutool-core/src/test/java/cn/hutool/core/thread/SyncUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/thread/SyncUtilTest.java
new file mode 100644
index 000000000..846b4614d
--- /dev/null
+++ b/hutool-core/src/test/java/cn/hutool/core/thread/SyncUtilTest.java
@@ -0,0 +1,36 @@
+package cn.hutool.core.thread;
+
+import cn.hutool.core.lang.Assert;
+import org.junit.Test;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * CompletableFuture工具类测试
+ *
+ * @author <achao1441470436@gmail.com>
+ * @since 2021/11/10 0010 21:15
+ */
+public class SyncUtilTest {
+
+	@Test
+	public void waitAndGetTest() {
+		CompletableFuture<String> hutool = CompletableFuture.supplyAsync(() -> {
+			ThreadUtil.sleep(3, TimeUnit.SECONDS);
+			return "hutool";
+		});
+		CompletableFuture<String> sweater = CompletableFuture.supplyAsync(() -> {
+			ThreadUtil.sleep(4, TimeUnit.SECONDS);
+			return "卫衣";
+		});
+		CompletableFuture<String> warm = CompletableFuture.supplyAsync(() -> {
+			ThreadUtil.sleep(5, TimeUnit.SECONDS);
+			return "真暖和";
+		});
+		// 等待完成
+		SyncUtil.wait(hutool, sweater, warm);
+		// 获取结果
+		Assert.isTrue("hutool卫衣真暖和".equals(SyncUtil.get(hutool) + SyncUtil.get(sweater) + SyncUtil.get(warm)));
+	}
+}