尝试读取资源时 ReaderWriterLock 阻塞

Question

我正在尝试将ReaderWriterLock 用于两个Tasks 之间的共享资源。由于某种原因，它开始无限期地等待：

class State {

        private const int TIMEOUT = 5000;
        private ReaderWriterLock lck = new ReaderWriterLock();
        private TimeSpan lastIssuedAt;

        public TimeSpan LastIssuedAt {
            get {

                this.lck.AcquireReaderLock(TIMEOUT);
                return this.lastIssuedAt;
            }
            set {
                this.lck.AcquireWriterLock(TIMEOUT);
                this.lastIssuedAt = value;
            }
        }
}

当一个任务尝试get 属性LastIssuedAt 它只是阻塞，我不明白为什么。

Answer 1

看看MSDN上的例子：https://docs.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlock?view=netframework-4.8

您忘记释放锁。这样做的常见模式是 try/finally：

ReaderWriterLock lck = new ReaderWriterLock();

lck.AcquireReaderLock(timeOut);
try
{
    // Do what needs to be done under the lock
}
finally 
{
    // Ensure that the lock is released.
    lck.ReleaseReaderLock();
}

另外，请查看 ReaderWriterLockSlim：https://docs.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlockslim?view=netframework-4.8 哪个 MSDN 推荐用于新开发。