锁定缓存密钥而不锁定整个缓存

String 在全球可见,所以他们是一个差劲的候选人。

ConcurrentMap 并行映射

ReadWriteLock trial = new ReentrantReadWriteLock(fair);
ReadWriteLock lock = locks.putIfAbsent(key, trial);
if (lock == null) {
  /* The current thread won the race to create lock for key. */
  lock = trial;
}

(使用 ReadWriteLock 是可选的;有了它,您可以做一些花哨的事情,比如允许多个线程同时读取缓存的值,但是当值需要更新时,仍然让另一个线程获得独占锁。)

java.util.concurrent . 在这种情况下,您可以在地图上同步:

Object lock;
synchronized (locks) {
  if (locks.containsKey(key))
    lock = locks.get(key);
  else {
    lock = new Object();
    locks.put(key, object);
  }
}

我考虑过锁定字符串“Bob”(因为由于实习,它总是同一个对象对吧?)。这样行吗?

I've previously tried this and it actually doesn't work quite like you might expect . 你一定要打电话 intern()

如果您正在使用地图进行缓存,那么锁定该键将执行您的建议。