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finnish 是一个标志，如果为 true 则说明整张表的迁移操作已经全部完成了，我们只需要重置 table 的引用并将 nextTable 赋为空即可。否则，CAS 式的将 sizeCtl 减一，表示当前线程已经完成了任务，退出扩容操作。如果退出成功，那么需要进一步判断是否还有其他线程仍然在执行...

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只允许一个线程对表进行初始化，若不巧有其他线程进来了，则会让其他线程交出 CPU 等待下次系统调度。这保证了表同时只会被一个线程初始化。//检测到桶结点是 ForwardingNode 类型，协助扩容 else if ((fh = f.hash) == MOVED) tab = helpTransf...

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为并发而生的 ConcurrentHashMap数据结构Java 7为实现并发访问，引入了Segment这一结构，实现了分段锁，理论上最大并发度与Segment个数相等。Java 8取消了基于 Segment 的分段锁思想，改用CAS + synchronized 控制并发操作，在某些方面提升了性能...

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Java 集合源码解析 - ConcurrentHashMap（JDK7）（上）

ConcurrentHashMap是线程安全且高效的HashMap1 为什么要使用ConcurrentHashMap线程不安全的HashMapHashMap是Java中最常用的一个Map类，性能好、速度快，但不能保证线程安全，它可用null作为key/valueHashMap的线程不安全主要体现在r...

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