diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-2/lesson-4/src/main/java/com/segmentfault/deep/in/java/collection/algorithm/QuickSort.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-2/lesson-4/src/main/java/com/segmentfault/deep/in/java/collection/algorithm/QuickSort.java"
index 1ce2988..8304c19 100644
--- "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-2/lesson-4/src/main/java/com/segmentfault/deep/in/java/collection/algorithm/QuickSort.java"	
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-2/lesson-4/src/main/java/com/segmentfault/deep/in/java/collection/algorithm/QuickSort.java"	
@@ -1,5 +1,6 @@
 package com.segmentfault.deep.in.java.collection.algorithm;
 
+import java.util.Arrays;
 import java.util.stream.Stream;
 
 public class QuickSort<T extends Comparable<T>> implements Sort<T> {
@@ -82,9 +83,9 @@ int partition(T[] values, int low, int high) {
     }
 
     public static void main(String[] args) {
-        Integer[] values = Sort.of(3, 1, 2, 5, 4);
+        Integer[] values = Sort.of(2, 5, 6, 7, 8, 8, 9, 2, 1, 6, 7, 5, 6, 11, 23);
         Sort<Integer> sort = new QuickSort<>(); // Java 7 Diamond 语法
         sort.sort(values);
-        Stream.of(values).forEach(System.out::println);
+        System.out.println(Arrays.asList(values));
     }
 }
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/pom.xml" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/pom.xml"
index 20aac00..fe88fd6 100644
--- "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/pom.xml"	
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/pom.xml"	
@@ -15,6 +15,7 @@
         <module>stage-3-lesson-1</module>
         <module>stage-3-lesson-2</module>
         <module>stage-3-lesson-3</module>
+        <module>stage-3-lesson-4</module>
     </modules>
     <packaging>pom</packaging>
 
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/pom.xml" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/pom.xml"
new file mode 100644
index 0000000..f4cef6e
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/pom.xml"	
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>stage-3</artifactId>
+        <groupId>com.segmentfault</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>stage-3-lesson-4</artifactId>
+    <name>「一入 Java 深似海 」系列 :: 第三期 :: 第四节</name>
+    <url>https://segmentfault.com/ls/1650000018320970/l/1500000018320681</url>
+</project>
\ No newline at end of file
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueConcurrentDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueConcurrentDemo.java"
new file mode 100644
index 0000000..7f04cbc
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueConcurrentDemo.java"	
@@ -0,0 +1,43 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class ArrayBlockingQueueConcurrentDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        // 最大允许添加 2 个元素
+        BlockingQueue<Integer> queue = new ArrayBlockingQueue<>(2, true);
+        // 申请 2 个大小的线程池
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+
+        for (AtomicInteger i = new AtomicInteger(1); i.get() < 100; i.incrementAndGet()) {
+            executorService.submit(() -> { // 写线程（1）
+                try {
+                    queue.put(i.get());
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+
+            executorService.submit(() -> { // 读线程（1）
+                try {
+                    System.out.println(queue.take());
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+        }
+
+//        executorService.submit(() -> { // 写线程（2）
+//            queue.put(2);
+//        });
+
+
+        executorService.awaitTermination(10, TimeUnit.SECONDS);
+        // 关闭线程池
+        executorService.shutdown();
+
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueDemo.java"
new file mode 100644
index 0000000..158b04d
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueDemo.java"	
@@ -0,0 +1,46 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+
+public class ArrayBlockingQueueDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        // ArrayBlockingQueue 是有限队列
+        ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue(3);
+
+        // Queue 添加操作中 offer 安全性高于 add 方法
+//        demoOfferMethod(queue);
+//        demoAddMethod(queue);
+
+        demoPutMethod(queue);
+        // BlockingQueue 要使用 put 方法多于 offer 方法
+
+        System.out.println(queue);
+    }
+
+    private static void demoPutMethod(BlockingQueue<Integer> queue) throws InterruptedException {
+        queue.put(1);
+        queue.put(2);
+        queue.put(3);
+        // 如果超过了 capacity，？
+        queue.put(4);
+    }
+
+    private static void demoAddMethod(BlockingQueue<Integer> queue) {
+        queue.add(1);
+        queue.add(2);
+        queue.add(3);
+        // 如果超过了 capacity，throw new IllegalStateException("Queue full")
+//        queue.add(4);
+    }
+
+    private static void demoOfferMethod(BlockingQueue<Integer> queue) {
+        queue.offer(1);
+        queue.offer(2);
+        queue.offer(3);
+        // 如果超过了 capacity，后面的offer 会被忽略
+        queue.offer(4);
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CompletableFutureDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CompletableFutureDemo.java"
new file mode 100644
index 0000000..3904c5d
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CompletableFutureDemo.java"	
@@ -0,0 +1,17 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.CompletableFuture;
+
+public class CompletableFutureDemo {
+
+    public static void main(String[] args) {
+        //  CompletableFuture
+
+        CompletableFuture.supplyAsync(() -> {
+            return 1;
+        }).thenApply(String::valueOf)
+            // 异常的方式结束
+            .completeExceptionally(new RuntimeException())
+        ;
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ConcurrentHashMapDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ConcurrentHashMapDemo.java"
new file mode 100644
index 0000000..cd11224
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ConcurrentHashMapDemo.java"	
@@ -0,0 +1,22 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+public class ConcurrentHashMapDemo {
+
+    public static void main(String[] args) {
+
+        // ConcurrentHashMap 读多写少场景
+        // 1.6 读（部分锁） -> 1.7 无锁（Segment） -> 1.8 无锁（红黑树——更好地解决 Hash 冲突）
+        // ConcurrentSkipListMap 读多写多场景（如果内存足够时）
+
+        //  ConcurrentHashMap
+        // table 2^n ->
+        // n = 1 -> size = 2
+        // n = 2 -> size = 2^2 = 4
+        // n = 3 -> size = 2^3 = 8 TREEIFY_THRESHOLD
+        // log2(8) = 3
+        // [0] -> [1] -> [2]
+        // [0] -> [1]
+        //     -> [2]
+        // n = 4 -> size = 2^4 = 16
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CopyOnWriteArrayListDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CopyOnWriteArrayListDemo.java"
new file mode 100644
index 0000000..4f00616
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CopyOnWriteArrayListDemo.java"	
@@ -0,0 +1,31 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.Iterator;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+public class CopyOnWriteArrayListDemo {
+
+    public static void main(String[] args) {
+        CopyOnWriteArrayList<Integer> list = new CopyOnWriteArrayList<>(); // Diamond 语法
+
+        // main 线程插入三条数据
+        // 安装 Thread ID
+        list.add(1);
+        // 判断当前线程 ID == main.threadId
+        list.add(2);
+        list.add(3);
+        // Copy
+        // JDK 升级两大核心性能提升
+        // 1. 数组
+        // 2. String
+
+        // ConcurrentModificationException
+        int times = 0;
+        Iterator iterator = list.iterator();
+        while (iterator.hasNext() && times < 100) {
+            iterator.next();
+            list.add(2);
+            times++;
+        }
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/HashMapDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/HashMapDemo.java"
new file mode 100644
index 0000000..bf748b7
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/HashMapDemo.java"	
@@ -0,0 +1,19 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class HashMapDemo {
+
+    public static void main(String[] args) {
+
+        String strValue = "Hello,World";
+
+        Integer intValue = new Integer(strValue.hashCode());
+
+        Map<Object, Object> map = new HashMap<>();
+
+        map.put(strValue, 1);
+        map.put(intValue, 2);
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/Java9FlowDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/Java9FlowDemo.java"
new file mode 100644
index 0000000..b5f9373
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/Java9FlowDemo.java"	
@@ -0,0 +1,72 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.*;
+
+public class Java9FlowDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        // Java 7 try-catch 语法
+
+        try (SubmissionPublisher<String> publisher = new SubmissionPublisher<>()) {
+
+            // 订阅
+            publisher.subscribe(new Flow.Subscriber<String>() {
+
+                private Flow.Subscription subscription;
+
+                @Override
+                public void onSubscribe(Flow.Subscription subscription) {
+                    this.subscription = subscription;
+                    println("已订阅");
+                    // 订阅无限(Long.MAX_VALUE)数据
+                    subscription.request(Long.MAX_VALUE);
+                }
+
+                @Override
+                public void onNext(String item) {
+                    if ("exit".equalsIgnoreCase(item)) {
+                        // 取消订阅
+                        subscription.cancel();
+                        return;
+                    } else if ("exception".equalsIgnoreCase(item)) {
+                        throw new RuntimeException("Throw an exception...");
+                    }
+                    println("得到数据：" + item);
+                }
+
+                @Override
+                public void onError(Throwable throwable) {
+                    println("得到异常：" + throwable);
+                }
+
+                @Override
+                public void onComplete() {
+                    println("操作完成");
+                }
+            });
+
+            // 发布者发布数据
+            publisher.submit("Hello,World");
+            publisher.submit("2019");
+
+            // 故意抛出异常
+            publisher.submit("exception");
+
+            // exit 是退出命令
+            publisher.submit("exit");
+            // 当 exit 出现时，忽略后续提交
+            publisher.submit("ABCDEFG");
+            publisher.submit("HIGKLMN");
+
+            ExecutorService executor = (ExecutorService) publisher.getExecutor();
+
+            executor.awaitTermination(100, TimeUnit.MILLISECONDS);
+
+        }
+    }
+
+    private static void println(Object object) {
+        System.out.printf("[线程: %s] - %s\n", Thread.currentThread().getName(), object);
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/LinkedBlockingQueueConcurrentDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/LinkedBlockingQueueConcurrentDemo.java"
new file mode 100644
index 0000000..dc284b5
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/LinkedBlockingQueueConcurrentDemo.java"	
@@ -0,0 +1,43 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class LinkedBlockingQueueConcurrentDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        // 最大允许添加 2 个元素
+        BlockingQueue<Integer> queue = new LinkedBlockingQueue<>(2);
+        // 申请 2 个大小的线程池
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+
+        for (AtomicInteger i = new AtomicInteger(1); i.get() < 100; i.incrementAndGet()) {
+            executorService.submit(() -> { // 写线程（1）
+                try {
+                    queue.put(i.get());
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+
+            executorService.submit(() -> { // 读线程（1）
+                try {
+                    System.out.println(queue.take());
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+        }
+
+//        executorService.submit(() -> { // 写线程（2）
+//            queue.put(2);
+//        });
+
+
+        executorService.awaitTermination(10, TimeUnit.SECONDS);
+        // 关闭线程池
+        executorService.shutdown();
+
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/MapEntryDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/MapEntryDemo.java"
new file mode 100644
index 0000000..cac5f24
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/MapEntryDemo.java"	
@@ -0,0 +1,51 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentSkipListMap;
+
+public class MapEntryDemo {
+
+    public static void main(String[] args) {
+        Map<String, Integer> map = new HashMap<>();
+        map.put("A", 1);
+        map.put("B", 2);
+        map.put("C", 3);
+        demoMap(map);
+
+        System.out.println(map);
+
+        //注意：Java Concurrent Map 可能未实现 Map.Entry#setValue(Object) 方法
+        Map<String, Integer> skipListMap = new ConcurrentSkipListMap<>();
+
+        skipListMap.put("A", 1);
+        skipListMap.put("B", 2);
+        skipListMap.put("C", 3);
+
+        demoMap(skipListMap);
+
+        System.out.println(skipListMap);
+    }
+
+    private static void demoMap(Map<String, Integer> map) {
+
+        // 问题：如何让所有的成员值 +1
+        for (Map.Entry<String, Integer> entry : map.entrySet()) {
+            slowApproach(entry, map);
+            fastApproach(entry);
+        }
+    }
+
+    private static void fastApproach(Map.Entry<String, Integer> entry) {
+        entry.setValue(entry.getValue() + 1);
+    }
+
+    private static void slowApproach(Map.Entry<String, Integer> entry, Map<String, Integer> map) {
+        String key = entry.getKey();
+        Integer value = entry.getValue();
+        // Key 的计算消耗时间
+        // +1
+        value += 1;
+        map.put(key, value);
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/QuickSortForkJoinDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/QuickSortForkJoinDemo.java"
new file mode 100644
index 0000000..5f9a124
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/QuickSortForkJoinDemo.java"	
@@ -0,0 +1,104 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.Arrays;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.RecursiveAction;
+import java.util.concurrent.TimeUnit;
+
+public class QuickSortForkJoinDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        Integer[] values = new Integer[]{2, 5, 6, 7, 8, 8, 9, 2, 1, 6, 7, 5, 6, 11, 23};
+
+        ForkJoinPool pool = new ForkJoinPool();
+
+        pool.submit(new QuickSortTask(values));
+
+        pool.awaitTermination(100, TimeUnit.MILLISECONDS);
+
+        pool.shutdown();
+
+        System.out.println(Arrays.asList(values));
+    }
+
+    private static class QuickSortTask extends RecursiveAction {
+
+        private final Integer[] parts;
+
+        private final int low;
+
+        private final int high;
+        // 设置一个阈值
+        private static final int THRESHOLD = 4;
+
+        private QuickSortTask(Integer[] parts) {
+            this.parts = parts;
+            this.low = 0;
+            this.high = parts.length - 1;
+        }
+
+        private QuickSortTask(Integer[] parts, int low, int high) {
+            this.parts = parts;
+            this.low = low;
+            this.high = high;
+        }
+
+        @Override
+        protected void compute() {
+            if (high - low < THRESHOLD) { // 范围低于阈值时，直接排序
+                sort(parts, low, high);
+            } else {
+                int pivot = partition(parts, low, high);
+                QuickSortTask task = new QuickSortTask(parts, low, pivot - 1);
+                QuickSortTask task2 = new QuickSortTask(parts, pivot + 1, high);
+                task.fork().join();
+                task2.fork().join();
+            }
+        }
+
+        /**
+         * 获取分区索引
+         *
+         * @param values 数组对象
+         * @param low    低位索引
+         * @param high   高位索引
+         * @return 分区索引
+         */
+        int partition(Integer[] values, int low, int high) {
+            // 获取 pivot = values[high]
+
+            // [3, 1, 2, 5, 4]
+            // pivot = 4
+            //              -1
+            // [0] = 3 < 4 (0)
+            // [1] = 1 < 4 (1)
+            // [2] = 2 < 4 (2)
+            // [3] = 5 > 4 (3)
+            // => [(3, 1, 2), (4), (5)]
+            // pIndex = 3
+
+            Integer pivot = values[high];
+            int i = low;
+
+            for (int j = low; j < high; j++) {
+                if (values[j].compareTo(pivot) < 1) { // <=
+                    Integer temp = values[i]; // 低位数据
+                    values[i] = values[j]; // 低位数据获取高位数据
+                    values[j] = temp;
+                    i++; // -1 -> 0
+                }
+            }
+
+            Integer temp = values[i];
+            values[i] = values[high];
+            values[high] = temp;
+
+            return i;
+        }
+
+        private void sort(Integer[] parts, int low, int high) {
+            Arrays.sort(parts, low, high + 1);
+        }
+    }
+}
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/SynchronousQueueDemo.java" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/SynchronousQueueDemo.java"
new file mode 100644
index 0000000..1728c3b
--- /dev/null
+++ "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\344\273\243\347\240\201/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/SynchronousQueueDemo.java"	
@@ -0,0 +1,72 @@
+package com.segmentfault.deep.in.java.concurrency;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class SynchronousQueueDemo {
+
+    public static void main(String[] args) throws InterruptedException {
+
+
+        // SynchronousQueue 互斥使用场景
+        // SynchronousQueue put() 完成之后，必须被其他线程 take()
+        // capacity == 0 , 又允许插入(put) 一个元素
+        // offer 方法无效，add 方法抛出异常
+        BlockingQueue<Integer> sQueue = new SynchronousQueue<>(true);
+        // 申请 2 个大小的线程池
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+
+        for (AtomicInteger i = new AtomicInteger(1); i.get() < 100; i.incrementAndGet()) {
+            executorService.execute(() -> { // 写线程
+                try {
+                    // 必须要有 put，不能用 offer
+                    // BlockingQueue 尽可能用 put，避免使用 offer，最好不要用 add
+                    // sQueue.offer(1); // 如果 SynchronousQueue 被其他线程调用 take() 方法的话，会发生死锁
+                    sQueue.put(i.get());
+                } catch (Exception e) {
+                    e.printStackTrace();
+                }
+            });
+
+            executorService.execute(() -> { // 读线程
+                try {
+                    System.out.println(sQueue.take());
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+        }
+
+        executorService.awaitTermination(10, TimeUnit.MICROSECONDS);
+
+        executorService.shutdown();
+    }
+
+    private static void synchronousQueuevsArrayBlockingQueue() throws InterruptedException {
+        // size == 0 特殊 ArrayBlockingQueue
+        BlockingQueue<Integer> sQueue = new SynchronousQueue<Integer>();
+        sQueue.put(1);
+
+        System.out.println(sQueue.size());
+
+        BlockingQueue<Integer> aQueue = new ArrayBlockingQueue<>(1);
+
+        aQueue.add(1);
+
+        System.out.println(aQueue.size());
+
+    }
+
+    // offer 方法来自于 Queue 接口，因此，子接口无法超越 Queue 方法签名
+
+    public boolean equals(Object object)
+//            throws Exception // 错误（编译时）：超越父类 Object equals(Object) 方法签名
+            throws RuntimeException // 非 checked 异常时没有以上限制
+    {
+
+        return false;
+    }
+}
+
+
+
diff --git "a/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\347\254\254\344\270\211\346\234\237/\347\254\254\345\233\233\350\212\202 Java \345\271\266\345\217\221\346\241\206\346\236\266\351\253\230\347\272\247\350\277\220\347\224\250/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215\347\263\273\345\210\227 \347\254\254\344\270\211\346\234\237 \347\254\254\345\233\233\350\212\202 \343\200\212Java \345\271\266\345\217\221\346\241\206\346\236\266\351\253\230\347\272\247\350\277\220\347\224\250\343\200\213.pdf" "b/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215/\347\254\254\344\270\211\346\234\237/\347\254\254\345\233\233\350\212\202 Java \345\271\266\345\217\221\346\241\206\346\236\266\351\253\230\347\272\247\350\277\220\347\224\250/\343\200\214\344\270\200\345\205\245 Java \346\267\261\344\274\274\346\265\267 \343\200\215\347\263\273\345\210\227 \347\254\254\344\270\211\346\234\237 \347\254\254\345\233\233\350\212\202 \343\200\212Java \345\271\266\345\217\221\346\241\206\346\236\266\351\253\230\347\272\247\350\277\220\347\224\250\343\200\213.pdf"
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