ArrayBlockingQueue使用单个锁进行插入和删除，但LinkedBlockingQueue使用2个单独的锁 [英] ArrayBlockingQueue uses a single lock for insertion and removal but LinkedBlockingQueue uses 2 separate locks

问题描述

我正在浏览ArrayBlockingQueue和LinkedBlockingQueue的源代码。 LinkedBlockingQueue有一个putLock和一个takeLock分别插入和删除，但ArrayBlockingQueue只使用一个锁。我相信LinkedBlockingQueue是基于简单，快速和实用的非阻塞和阻塞
并发队列算法。在本文中，他们提到他们保留一个虚拟节点，使入口队从不必访问头和出列队员从来没有访问尾，避免了死锁场景。我想知道为什么ArrayBlockingQueue不借用相同的想法和使用2锁代替。

I was going through the source code of ArrayBlockingQueue and LinkedBlockingQueue. LinkedBlockingQueue has a putLock and a takeLock for insertion and removal respectively but ArrayBlockingQueue uses only 1 lock. I believe LinkedBlockingQueue was implemented based on the design described in Simple, Fast, and Practical Non-Blocking and Blocking Concurrent Queue Algorithms. In this paper, they mention that they keep a dummy node so that enqueuers never have to access head and dequeuers never have to access tail which avoids deadlock scenarios. I was wondering why ArrayBlockingQueue doesn't borrow the same idea and use 2 locks instead.

推荐答案

ArrayBlockingQueue必须避免重写条目它需要知道开始和结束的位置。 LinkedBlockQueue不需要知道这一点，因为它让GC担心清理队列中的节点。

ArrayBlockingQueue has to avoid overwriting entries so that it needs to know where the start and the end is. A LinkedBlockQueue doesn't need to know this as it lets the GC worry about cleaning up Nodes in the queue.

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