diff --git a/week_04/18/ArrayBlockingQueue.md b/week_04/18/ArrayBlockingQueue.md
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+# ArrayBlockingQueue
+[ArrayBlockingQueue 详细源码解析 - 简书](https://www.jianshu.com/p/3fedd6e53cf9)
+[死磕java concurrent包系列（四）基于AQS的条件队列彻底理解ArrayBlockingQueue - 简书](https://www.jianshu.com/p/3a77478658ec)
+## Why use
+1. 从线程安全,如何调度,是否有界,支持的操作等方面谈谈ArrayBlockingQueue的特点?
+![](ArrayBlockingQueue/C26216E7-9E90-443F-8E80-BC17C60151FD.png)
+
+## 数据结构
+1. ArrayBlockingQueue的数据结构设计为什么需要维护两个指针takeIndex,putIndex?用来解决什么问题?
+
+![](ArrayBlockingQueue/F69855D7-1455-49B2-977A-1DEE07EF08D4.png)
+
+2. ArrayBlockingQueue的数据结构是怎样的?
+![](ArrayBlockingQueue/72205113-EE4C-428E-90DA-2E16CEE02444.png)
+
+3. ArrayBlockingQueue的数据结构中Condition notEmpty;Condition notFull这两个属性的作用?
+![](ArrayBlockingQueue/ABA927E1-1D53-4FD1-82DF-2B8B0D2015C4.png)
+
+
+
+## 入队操作
+1. ArrayBlockingQueue中的元素统一入队操作enqueue 的执行过程?
+
+![](ArrayBlockingQueue/5FB720BE-8FAF-4D2B-BA7D-46EB5902E936.png)
+
+2. ArrayBlockingQueue中的元素统一入队操作enqueue 的执行过程中putIndex 进行自增，当达到数组长度的时候，putIndex 重头再来，即设置为0,为什么?
+![](ArrayBlockingQueue/5C4B5DCA-74B4-487A-A33F-809F38AAB65E.png)
+
+
+
+
+3. ArrayBlockingQueue中入队操作 add 和 offer 方法的区别?
+![](ArrayBlockingQueue/B4B3D5A8-4AC8-466A-AE37-7C62C187BCA0.png)
+
+4. ArrayBlockingQueue中入队操作方法 put 和add,offer方法 的区别?它的执行过程?
+![](ArrayBlockingQueue/06CC7154-F4C4-48E3-913B-ABD3C9F8428C.png)
+
+
+## 出队操作
+1. ArrayBlockingQueue中的元素统一入队操作dequeue 的执行过程?
+![](ArrayBlockingQueue/868AF4E7-46E8-4367-AC55-D7216CB0F648.png)
+2. ArrayBlockingQueue中出队的非阻塞提取方法 peek和 poll 的区别?
+![](ArrayBlockingQueue/A114AB78-E806-4A60-9B6B-AC2F8A0114D6.png)
+3. ArrayBlockingQueue中出队的阻塞提取方法take 的执行过程?
+
+![](ArrayBlockingQueue/9AEE3C00-C193-4492-8869-FC01E13BDDD2.png)
+
+
+
+4. ArrayBlockingQueue中通过 remove移除对应的元素过程?删除时会遇到哪两种情况?删除后为什么需要维护迭代器实例变量?
+![](ArrayBlockingQueue/6A29537E-ED0A-44CC-BB48-D7F77A340056.png)
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@@ -0,0 +1,47 @@
+# ConcurrentHashMap 1.8
+[ConcurrentHashMap源码解析（1）-社区博客-网易云](https://sq.163yun.com/blog/article/233752108046987264)
+[Java 源码分析-ConcurrentHashMap(1.8) - 简书](https://www.jianshu.com/p/c7f85caa0b3f)
+[基于 cas 机制的 concurrenthashmap 实现内幕 | 指 · 间](https://www.zhenchao.org/2019/01/31/java/cas-based-concurrent-hashmap/)
+[J.U.C 并发集合（一）：ConcurrentHashMap基础 | 陈树义](http://shuyi.me/2019/09/25/java_concurrent_collection/java_concurrent_collection_01_concurrent_hash_map_01/)
+[并发容器之ConcurrentHashMap(JDK 1.8版本) - 简书](https://www.jianshu.com/p/e6ed5af68de2)
+[面试必问之 ConcurrentHashMap 线程安全的具体实现方式 | Just Do Java](http://www.justdojava.com/2019/12/18/java-collection-15/)
+[为并发而生的 ConcurrentHashMap（Java 8） - 云+社区 - 腾讯云](https://cloud.tencent.com/developer/article/1013643)
+[J.U.C 并发集合（二）：ConcurrentHashMap 扩容 | 陈树义](http://shuyi.me/2019/09/25/java_concurrent_collection/java_concurrent_collection_02_concurrent_hash_map_02/)
+## Why use 
+## Segment
+
+## 重要数据结构
+1. ConcurrentHashMap中的内部静态类 Node<K,V> 的作用?和 HashMap 中的有什么区别?
+
+![](ConcurrentHashMap%201.8/E8EF68C1-DB89-4F9D-BE87-B38A4E592232.png)
+
+2. ConcurrentHashMap中的静态内部类 TreeNode<K,V> 的作用?
+
+![](ConcurrentHashMap%201.8/964C34C6-3328-4BDF-BA8E-2FA4287E7275.png)
+
+
+3. ConcurrentHashMap中的静态内部类 ForwardingNode<K,V> 的作用?
+![](ConcurrentHashMap%201.8/E3FF7CC7-8210-4871-8769-6012FD104C93.png)
+
+4. ConcurrentHashMap中的静态内部类 ReservationNode<K, V> 的作用?
+![](ConcurrentHashMap%201.8/CDF80BCE-92E7-4EC0-8A77-4C32BACE6959.png)
+
+## 构造函数
+	1. ConcurrentHashMap中提供的构造函数的特点?
+![](ConcurrentHashMap%201.8/A486FB92-EC45-493C-AB5A-E5BA60D788AE.png)
+
+## put 插入操作
+1. ConcurrentHashMap中通过initTable 初始化数组的过程?在该方法调用过程中可以看出实例变量**sizeCtl**的作用?
+
+![](ConcurrentHashMap%201.8/923EFA14-0EE3-45DA-A4E9-436B08FC79AB.png)
+2. ConcurrentHashMap中帮助扩容的方法helpTransfer的触发条件?执行过程?
+![](ConcurrentHashMap%201.8/007536A9-F050-46C3-A3B9-3FA1BDFC79D8.png)
+3. ConcurrentHashMap中 put()插入操作的结尾处调用了addCount方法做了哪两件事?执行过程是怎样的?
+![](ConcurrentHashMap%201.8/C2E1605A-70E2-43AA-8E4F-60576C5B5FF1.png)
+4. ConcurrentHashMap中扩容逻辑的具体实现?(待补充)
+	1.  [为并发而生的 ConcurrentHashMap（Java 8） - 云+社区 - 腾讯云](https://cloud.tencent.com/developer/article/1013643)
+	2. [多线程十二之ConcurrentHashMap1.8实现分析 – Python量化投资](https://www.lizenghai.com/archives/4639.html)
+	3. [基于 cas 机制的 concurrenthashmap 实现内幕 | 指 · 间](https://www.zhenchao.org/2019/01/31/java/cas-based-concurrent-hashmap/)
+	4. [J.U.C 并发集合（二）：ConcurrentHashMap 扩容 | 陈树义](http://shuyi.me/2019/09/25/java_concurrent_collection/java_concurrent_collection_02_concurrent_hash_map_02/)
+5. ConcurrentHashMap中 put()插入操作的总体流程? 注意过程中为什么 f.hash>0,代表的是链表的头结点?
+![](ConcurrentHashMap%201.8/5A5E23E7-ECB9-4703-BA37-4D5F78B1ADE0.png)
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diff --git a/week_04/18/ConcurrentLinkedQueue.md b/week_04/18/ConcurrentLinkedQueue.md
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@@ -0,0 +1,61 @@
+# ConcurrentLinkedQueue
+## 参考
+[【Java并发编程】—–“J.U.C”：ConcurrentLinkedQueue - 简书](https://www.jianshu.com/p/32d6526494fd)
+[ConcurrentLinkedQueue原理解析 - 简书](https://www.jianshu.com/p/b9fa382926e0)
+[并发容器-ConcurrentLinkedQueue详解 - 简书](https://www.jianshu.com/p/231caf90f30b)
+## Why use
+1. 为什么要引入ConcurrentLinkedQueue?
+
+![](ConcurrentLinkedQueue/FE61C37A-2361-4CD3-B14D-7BF4A126617D.png)
+2. ConcurrentLinkedQueue具有哪些特点?
+![](ConcurrentLinkedQueue/34698E77-E06C-454B-88B4-636601A79B97.png)
+
+## 数据结构
+1. ConcurrentLinkedQueue的类结构是怎样的?
+
+![](ConcurrentLinkedQueue/F3DA5DAD-F922-45F3-BD11-2616363FC424.png)
+
+2. ConcurrentLinkedQueue的静态内部类 Node 的类结构是怎样的?有什么作用?
+![](ConcurrentLinkedQueue/E7061624-37BB-4ED7-9EB8-F07FA6918C1B.png)
+
+3. ConcurrentLinkedQueue中包含哪几种类型的节点?
+
+![](ConcurrentLinkedQueue/8D54E941-4B4F-4C3D-8BCE-04DC4EF27C35.png)
+
+4. ConcurrentLinkedQueue的源代码分析中，我们将会看到队列有时会处于不一致状态。为此，ConcurrentLinkedQueue 使用三个不变式 ( **基本不变式，head 的不变式和 tail 的不变式** )，来约束队列中方法的执行。通过这三个不变式来维护非阻塞算法的正确性,这三个不变式是怎样的(不变式,即不变性约束)?
+
+![](ConcurrentLinkedQueue/D63E6E8A-9F25-48F1-BB76-6213BD03CF04.png)
+
+5. ConcurrentLinkedQueue中 head 节点的不变性和可变性约束?
+
+![](ConcurrentLinkedQueue/6476B071-05F6-42EC-B641-2A1EBF2AFBC0.png)
+
+6. ConcurrentLinkedQueue中 tail 节点的不变性和可变性约束?
+
+![](ConcurrentLinkedQueue/D1AB030A-86C2-4F66-BFE1-3429DF035E1C.png)
+
+## 入队
+1. ConcurrentLinkedQueue入队过程中队列添加第一个节点后的情况?tail 节点的指向?这种情况对应代码的执行过程?
+![](ConcurrentLinkedQueue/8FD5BD88-6620-4CAD-879B-EBBA37F201AB.png)
+
+
+2. ConcurrentLinkedQueue入队过程中队列添加第二个节点后的情况?此时tail 节点的指向?这种情况对应代码的执行过程?
+![](ConcurrentLinkedQueue/854071A2-EAB7-4182-B43A-923B6898D792.png)
+
+
+3. ConcurrentLinkedQueue入队过程中的`t != (t = tail)` 这个判断的代码,如何理解,什么时候结果会是 false?
+![](ConcurrentLinkedQueue/806693FC-DF81-4820-B285-9A79DB56BDEE.png)
+
+4. 在并发环境，ConcurrentLinkedQueue入列线程安全考虑具体可分哪2类?
+![](ConcurrentLinkedQueue/EA28788D-1E59-4212-9E94-ABA681949597.png)
+5. ConcurrentLinkedQueue入队过程中,执行到 p==q 的场景(即 tail 节点滞后的情况,此时 tail 节点已脱落,成为了哨兵节点)?
+![](ConcurrentLinkedQueue/0056E67E-28C1-46E0-8DB4-ED1ED96FDBCE.png)
+
+## 出队
+1. ConcurrentLinkedQueue出队过程中删除第一个节点的情况?删除第一个节点过程中head的指向是如何变换的?
+
+![](ConcurrentLinkedQueue/DE5E88BC-9A3A-46AF-9555-EB009971D72A.png)
+
+
+2. ConcurrentLinkedQueue出队过程中删除第二个节点,第三个节点时的情况?过程中head的指向是如何变换的?
+![](ConcurrentLinkedQueue/61A22E30-423A-4AF6-AFFB-9ECB153EAA95.png)
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diff --git a/week_04/18/CopyOnWriteArrayList.md b/week_04/18/CopyOnWriteArrayList.md
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+++ b/week_04/18/CopyOnWriteArrayList.md
@@ -0,0 +1,40 @@
+# CopyOnWriteArrayList
+[CopyOnWriteArrayList你都不知道，怎么拿offer？ - 掘金](https://juejin.im/post/5be23e6ef265da6135720d61)
+## Why use
+1. 为什么引入CopyOnWriteArrayList,它解决了什么问题?
+![](CopyOnWriteArrayList/C03EB474-D22A-4069-9D5B-6F65C158A139.png)
+
+2. 什么场景下使用CopyOnWriteArrayList?它的特点和实现原理?
+
+![](CopyOnWriteArrayList/09B01D7F-3469-42F2-A4A5-74D3EAFEF3B4.png)
+
+## 数据结构
+	1. **CopyOnWriteArrayList**类关系是怎样的?
+
+
+## 方法
+1. CopyOnWriteArrayList中 add 方法的实现?
+![](CopyOnWriteArrayList/6AC2754D-AF3E-4EE0-84F7-CD4155E77FF6.png)
+
+2. CopyOnWriteArrayList中 remove 方法的实现?
+![](CopyOnWriteArrayList/35698580-FDA6-4F12-A10A-9FB1B8FF22B7.png)
+
+## COWIterator
+
+	1. CopyOnWriteArrayList中**为什么遍历时不用调用者显式加锁**?
+![](CopyOnWriteArrayList/FB943C0F-34AE-4BC8-9928-792499D85E5C.png)
+
+
+
+
+
+
+## 设计
+1. question
+![](CopyOnWriteArrayList/1F8EFC7E-779E-4364-86C4-6273DA798830.png)
+	- answer
+![](CopyOnWriteArrayList/3EBD03D2-A1C0-40B9-8229-36B9993CF07A.png)
+
+2. **CopyOnWriteArrayList缺点**?
+
+![](CopyOnWriteArrayList/7507814A-C082-4E81-8F17-15D66C7511F8.png)
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