之前分布式锁中使用redisson的lock.tryLock(0,0,TimeUnit.SECONDS)

这么做的逻辑是releaseTime设置为0，实际上会使用默认的30s并触发看门狗机制

那waitTime有没有默认值呢？设置为0实际会等待多少时间？

看源码

 public boolean tryLock(long waitTime, long leaseTime, TimeUnit unit) throws InterruptedException {long time = unit.toMillis(waitTime);long current = System.currentTimeMillis();long threadId = Thread.currentThread().getId();Long ttl = this.tryAcquire(waitTime, leaseTime, unit, threadId);if (ttl == null) {return true;} else {time -= System.currentTimeMillis() - current;if (time <= 0L) {this.acquireFailed(waitTime, unit, threadId);return false;} else {........

这里的time直接就取的传入的waitTime，当time减少到小于0时，返回加锁失败！

所以waitTime是没有什么默认值的，这么写相当于加锁失败立刻返回

实验一下，先加一个不会过期的锁，然后另一个线程试图获取锁

@Testpublic void getLock() throws InterruptedException {String lockKey = "testLock";RLock lock = redissonClient.getLock(lockKey);System.out.println(System.currentTimeMillis());Boolean isLock = lock.tryLock(0,-1,TimeUnit.SECONDS);System.out.println(System.currentTimeMillis());System.out.println(isLock);}

如果设置为0，在尝试获取不到锁后立刻就会返回失败