ReaderWriterLockSlim和异步\\的await [英] ReaderWriterLockSlim and async\await

问题描述

我有一些问题 ReaderWriterLockSlim 。我不明白它是如何工作的魔法

I have some problems with ReaderWriterLockSlim. I cannot understand how it's magic working.

我的code：

 private async Task LoadIndex()
    {
        if (!File.Exists(FileName + ".index.txt"))
        {
            return;
        }
        _indexLock.EnterWriteLock();// <1>
        _index.Clear();
        using (TextReader index = File.OpenText(FileName + ".index.txt"))
        {
            string s;
            while (null != (s = await index.ReadLineAsync()))
            {
                var ss = s.Split(':');
                _index.Add(ss[0], Convert.ToInt64(ss[1]));
            }
        }
        _indexLock.ExitWriteLock();<2>
    }

当我在与下进写锁; 1>，调试器，我可以看到 _indexLock.IsWriteLockHeld 是真正，但当执行步骤2>我看到 _indexLock.IsWriteLockHeld 是假
和 _indexLock.ExitWriteLock 抛出异常 SynchronizationLockException 与消息写入锁没有被关押被释放。我做错了吗？

When I enter write lock at <1>, in debugger I can see that _indexLock.IsWriteLockHeld is true, but when execution steps to <2> I see _indexLock.IsWriteLockHeld is false and _indexLock.ExitWriteLock throws an exception SynchronizationLockException with message "The write lock is being released without being held". What I doing wrong?

推荐答案

ReaderWriterLockSlim 是一个线程仿射锁型，所以它通常不能与使用异步和等待。

ReaderWriterLockSlim is a thread-affine lock type, so it usually cannot be used with async and await.

您应该要么使用 SemaphoreSlim 与 WaitAsync ，或者（如果你的真正的需要读/写器锁），用我的<一个href=\"http://nitoasyncex.$c$cplex.com/wikipage?title=AsyncReaderWriterLock&referringTitle=Documentation\"><$c$c>AsyncReaderWriterLock从AsyncEx 或斯蒂芬Toub的 AsyncReaderWriterLock 。

You should either use SemaphoreSlim with WaitAsync, or (if you really need a reader/writer lock), use my AsyncReaderWriterLock from AsyncEx or Stephen Toub's AsyncReaderWriterLock.

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