Read/Write Lock

iteye_10104

于 2005-10-31 16:00:00 发布

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分类专栏： java基础文章标签： thread HTML

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博客介绍了一个线程读写锁的示例，当写锁未被持有时，所有线程可同时操作；当请求写锁时，请求线程需等待所有现有读操作完成，且后续读操作将被阻止，之后写线程才能开始。

  SomeContainer   Set<element> elements;  ReadWriteLock globalLock;  Lock readLock;  Lock writeLock; SomeContainer()   elements =  HashSet<element>();  globalLock =  ReentrantReadWriteLock();  readLock = globalLock.readLock();  writeLock = globalLock.writeLock();     addElement(Element elem)   writeLock.lock();      elements.add(elem);        writeLock.unlock();        processElements(ElementProcessor processor)   readLock.lock();      Iterator<element> iter = elements.iterator();    (iter.hasNext())      Element element = iter.next();     processor.processElement(element);        readLock.unlock();    ElementProcessor   processElement(Element element);</element></element></element>

So, in the example above, the first line in processElements will let everybody play at once so long as the write lock is not held. Then, when the write lock is requested, the requesting thread will be made to wait until all existing readers are done (no further readers will be let in), and then the writer thread may begin.

http://www.javalobby.com/java/forums/t45090.html