Java并发的集合.ppt

Java并发集合 并发集合类 ConcurrentHashMap ConcurrentLinkedQueue ConcurrentSkipListMap ConcurrentSkipListSet CopyOnWriteArrayList CopyOnWriteArraySet ArrayBlockingQueue LinkedBlockingQueue PriorityBlockingQueue LinkedBlockingDeque LinkedTransferQueue DelayQueue SynchronousQueue ConcurrentHashMap ConcurrentHashMap是线程安全且高效的HashMap ConcurrentHashMap的锁分段技术 ConcurrentHashMap 定位Segment final SegmentK,V segmentFor(int hash) { return segments[(hash segmentShift) segmentMask];} 定位HashEntry HashEntryK,V getFirst(int hash) { HashEntryK,V[] tab = table; return tab[hash (tab.length - 1)];} ConcurrentHashMap JDK6， 7 JDK8 CopyOnWriteArrayList Copy-On-Write : 写时复制 线程安全的、并且读操作无锁的ArrayList 读写分离思想 读多，写少，批量写 CopyOnWriteArrayList CopyOnWriteArrayList 写操作会加锁，新建一个数组，替换原来的。 CopyOnWriteArrayList 读操作不加锁 CopyOnWriteArrayList COWIterator是阉割版的Iterator. 每次迭代的是一个snapshot，不支持remove，set和add CopyOnWriteArraySet private final CopyOnWriteArrayListE al; //add addAll public boolean add(E e) { return al.addIfAbsent(e);} 重写equals ArrayBlockingQueue 用数组实现的有界阻塞队列 公平锁和非公平锁 Condition ArrayBlockingQueue 构造函数，需要指定一个capacity，默认是非公平锁fair=false ArrayBlockingQueue 读写都加锁 ArrayBlockingQueue Iterator弱一致性 不会抛出ConcurrentModificationException LinkedBlockingQueue 用链表实现的有界阻塞队列 /** Lock held by take, poll, etc */private final ReentrantLock takeLock = new ReentrantLock();/** Wait queue for waiting takes */private final Condition notEmpty = takeLock.newCondition();/** Lock held by put, offer, etc */private final ReentrantLock putLock = new ReentrantLock();/** Wait queue for waiting puts */private final Condition notFull = putLock.newCondition(); PriorityBlockingQueue 支持优先级的无界阻塞队列 private final PriorityQueueE q; private final ReentrantLock lock = new ReentrantLock(true);private final Condition notEmpty = lock.newCondition(); LinkedBlockingDeque 由链表结构组成的双向阻塞队列 可以运用在“工作窃取(work-stealing)”模式中 DelayQueue 支持延时获取元素的无界阻塞队列 : DelayQueueE extends Delayed private transient final ReentrantLock lock = new ReentrantLo