ConcurrentHashMap源码学习分析-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_41440097/article/details/101420841

本文详细探讨了ConcurrentHashMap的源码实现，重点分析了其并发控制和数据结构的设计，帮助理解如何在高并发场景下保证数据的正确性和性能。

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ConcurrentHashMap源码学习分析

类注释的翻译：

	/*是一种支持 全并发查询操作和高并发修改操作的哈希表*/
	A hash table supporting full concurrency of retrievals and high expected concurrency for updates.
	/*查询操作不加锁，因此会和修改操作冲突，所以查询操作返回的是最新修改的值*/
	Retrieval operations (including {@code get}) generally do not block. so may 
overlap with update operations (including {@code put} and {@code remove}).Retrievals 
reflect the results of the most recently <em>completed</em> update operations holding upon their onset.
	/*对于批量修改操作，查询操作获取的结果可能是修改操作完成后的子集，换个说法，查询操作获取的结果是整个Hashtable的snapshot*/
	For aggregate operations such as {@code putAll} and {@code clear}, concurrent retrievals may reflect insertion or removal of only some entries.
	/*对于需要扫描整个table的表来说，必须是单线程的，因此会给整个table加锁*/
	Bear in mind that the results of aggregate status methods including {@code size}, {@code isEmpty}, and {@code containsValue} are typically useful only when a map is not undergoing concurrent updates in other threads.

public class ConcurrentHashMap<K,V> extends AbstractMap<K,V>
    implements ConcurrentMap<K,V>, Serializable

继承AbstractMap类，实现ConcurrentMap、Serializable 接口。