Java：具有优先级的ReentrantReadWriteLock [英] Java : ReentrantReadWriteLock with priority

问题描述

以下是典型的读写器模式（大量读取和少量写入）

The following is the typical reader and writer pattern (a lot of reads and few writes)

  private ReadWriteLock lock = new ReentrantReadWriteLock();
  private int value;

  public void writeValue(int newValue){
       lock.writeLock().lock();
       try{
           this.value = newValue;
       }
       finally{
           lock.writeLock().unlock();
       }
  }

  public int readValue(){
       lock.readLock().lock();
       try{
           return value;
       }
       finally{
           lock.writeLock().unlock();
       }
  }

我想知道是否有可能优先考虑作家和读者？例如，通常编写者可能会等待很长时间（可能永远），如果其他线程持有读取锁定，那么是否可以让编写器具有更高的优先级，因此每当编写器出现时，它都可以被认为是正如高优先级（跳过线）类似的东西。

I am wondering that is it possible to have priority to writer and reader ? For example, normally writer could wait a very long time (maybe forever) if there are constantly read locks held by other thread, so is it possible to have writer with higher priority, so whenever a writer comes it can be considered as it's being as high priority (skip line) something like that.

推荐答案

根据 javadoc ，jdk实现不有任何读者/作家优先。但是，如果你使用公平实现，那么锁 以fifo顺序被授予（仍然没有读者/作者偏好），所以至少未来的读者不会阻止等待的作者。

According to the javadoc, the jdk implementation does not have any reader/writer priority. however, if you use the "fair" implementation, then the lock is granted in fifo order (still no reader/writer preference), so at least future readers will not block waiting writers.

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