讀寫鎖是以 ReaderWriterLockSlim 對象作為鎖管理資源的，不同的 ReaderWriterLockSlim 對象中鎖定同一個文件也會被視為不同的鎖進行管理，這種差異可能會再次導致文件的並發寫入問題，所以 ReaderWriterLockSlim 應盡量定義為只讀的靜態對象。

多線程同時寫入文件

class Program
    {
        static int writeCount = 0;
        static int wrongCount = 0;
        static void Main(string[] args)
        {
            Test();
        }
        
 
static void Test()
        {
            //叠代運行寫入內容，由於多個線程同時寫入同一個文件將會導致錯誤
            Parallel.For(0, 100, e =>
            {
                try
                {
                    writeCount++;
                    var logFilePath = "/test.txt";
                    var now = DateTime.Now;
                    
 
var logContent = string.Format("Tid: {0}{1} {2}=>{3}\r\n", Thread.CurrentThread.ManagedThreadId.ToString().PadRight(4), now.ToLongDateString(), now.ToLongTimeString(), writeCount);

                    File.AppendAllText(logFilePath, logContent);
                }
                catch (Exception ex)
                {
                    wrongCount
 
++;
                    Console.WriteLine("累計失敗" + wrongCount + "次");
                    Console.WriteLine(ex.Message);
                    throw;
                }
            });

            Console.Read();
        }
    }

運行結果

只有部分數據寫入了文件

多線程使用讀寫鎖同步寫入文件

class Program
    {
        static int writeCount = 0;
        static int wrongCount = 0;
        static void Main(string[] args)
        {
            Test();
        }
        static ReaderWriterLockSlim writeLock = new ReaderWriterLockSlim();
        static void Test()
        {
            //叠代運行寫入內容
            Parallel.For(0, 100, e =>
            {
                try
                {
                    writeLock.EnterWriteLock();
                    writeCount++;
                    var logFilePath = "/test.txt";
                    var now = DateTime.Now;
                    var logContent = string.Format("Tid: {0}{1} {2}=>{3}\r\n", Thread.CurrentThread.ManagedThreadId.ToString().PadRight(4), now.ToLongDateString(), now.ToLongTimeString(), writeCount);

                    File.AppendAllText(logFilePath, logContent);
                }
                catch (Exception ex)
                {
                    wrongCount++;
                    Console.WriteLine("累計失敗" + wrongCount + "次");
                    Console.WriteLine(ex.Message);
                    throw;
                }
                finally
                {
                    writeLock.ExitWriteLock();
                }
            });

            Console.Read();
        }
    }

運行成功，數據全部寫入文件

C#使用讀寫鎖解決多線程並發寫入文件時線程同步的問題