C#使用读写锁解决多线程并发写入文件时线程同步的问题

读写锁是以 ReaderWriterLockSlim 对象作为锁管理资源的，不同的 ReaderWriterLockSlim 对象中锁定同一个文件也会被视为不同的锁进行管理，这种差异可能会再次导致文件的并发写入问题，所以 ReaderWriterLockSlim 应尽量定义为只读的静态对象。

多线程同时写入文件

class Program
    {
        static int writeCount = 0;
        static int wrongCount = 0;
        static void Main(string[] args)
        {
            Test();
        }
        static void Test()
        {
            //迭代运行写入内容，由于多个线程同时写入同一个文件将会导致错误
            Parallel.For(0, 100, e =>
            {
                try
                {
                    writeCount++;
                    var logFilePath = "/test.txt";
                    var now = DateTime.Now;
                    var logContent = string.Format("Tid: {0}{1} {2}=>{3}
", Thread.CurrentThread.ManagedThreadId.ToString().PadRight(4), now.ToLongDateString(), now.ToLongTimeString(), writeCount);

                    File.AppendAllText(logFilePath, logContent);
                }
                catch (Exception ex)
                {
                    wrongCount++;
                    Console.WriteLine("累计失败" + wrongCount + "次");
                    Console.WriteLine(ex.Message);
                    throw;
                }
            });

            Console.Read();
        }
    }

运行结果

只有部分数据写入了文件

多线程使用读写锁同步写入文件

class Program
    {
        static int writeCount = 0;
        static int wrongCount = 0;
        static void Main(string[] args)
        {
            Test();
        }
        static ReaderWriterLockSlim writeLock = new ReaderWriterLockSlim();
        static void Test()
        {
            //迭代运行写入内容
            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}
", Thread.CurrentThread.ManagedThreadId.ToString().PadRight(4), now.ToLongDateString(), now.ToLongTimeString(), writeCount);

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

            Console.Read();
        }
    }

运行成功，数据全部写入文件