（注意：虽然我想了解.Net 4.0的未来想法，但我只限于此项目的.Net 3.5。）
我有一个线程，它从外部设备异步读取数据（在代码示例中通过创造性的strSomeData :-)模拟并将其存储在StringBuilder'缓冲区'中（strBuilderBuffer： - ）
在'主要代码'中我想在这个'缓冲区'''唠叨'。但是，从“操作”的角度来看，我不确定如何以线程安全的方式执行此操作。我理解从“数据”的角度看它是安全的，因为根据msdn，“这个（StringBuilder）类型的任何公共静态成员都是线程安全的。任何实例成员都不能保证是线程安全的。”但是，下面的代码说明从“运营”角度来看，它可能不是线程安全的。
关键是我担心两行代码：
string strCurrentBuffer = ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.ToString();
// Thread 'randomly' slept due to 'inconvenient' comp resource scheduling...
ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.Length = 0;
如果计算机操作系统在缓冲区的“读取”和“读取”之间休眠。缓冲区的'清除'，我可以丢失数据（这很糟糕： - （
有没有办法保证'atomocy？'这两条线和强迫计算机不要打断它们？
关于弗拉德下面关于使用lock的建议，我尝试了但是它没有用（实际上是真的）：
public void BufferAnalyze()
{
String strCurrentBuffer;
lock (ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer)
{
strCurrentBuffer = ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.ToString();
Console.WriteLine("[BufferAnalyze()] ||<< Thread 'Randomly' Slept due to comp resource scheduling");
Thread.Sleep(1000); // Simulate poor timing of thread resourcing...
ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.Length = 0;
}
Console.WriteLine("[BufferAnalyze()]\r\nstrCurrentBuffer[{0}] == {1}", strCurrentBuffer.Length.ToString(), strCurrentBuffer);
}
有没有更好的方法来实现线程安全缓冲区？
这是完整的代码：
namespace ExploringThreads
{
/// <summary>
/// Description of BasicThreads_TestThreadSafety_v1a
/// </summary>
class ThreadWorker_TestThreadSafety_v1a
{
private Thread thread;
public static StringBuilder strBuilderBuffer = new StringBuilder("", 7500);
public static StringBuilder strBuilderLog = new StringBuilder("", 7500);
public bool IsAlive
{
get { return thread.IsAlive; }
}
public ThreadWorker_TestThreadSafety_v1a(string strThreadName)
{
// It is possible to have a thread begin execution as soon as it is created.
// In the case of MyThread this is done by instantiating a Thread object inside MyThread's constructor.
thread = new Thread(new ThreadStart(this.threadRunMethod));
thread.Name = strThreadName;
thread.Start();
}
public ThreadWorker_TestThreadSafety_v1a() : this("")
{
// NOTE: constructor overloading ^|^
}
//Entry point of thread.
public void threadRunMethod()
{
Console.WriteLine("[ThreadWorker_TestThreadSafety_v1a threadRunMethod()]");
Console.WriteLine(thread.Name + " starting.");
int intSomeCounter = 0;
string strSomeData = "";
do
{
Console.WriteLine("[ThreadWorker_TestThreadSafety_v1a threadRunMethod()] running.");
intSomeCounter++;
strSomeData = "abcdef" + intSomeCounter.ToString() + "|||";
strBuilderBuffer.Append(strSomeData);
strBuilderLog.Append(strSomeData);
Thread.Sleep(200);
} while(intSomeCounter < 15);
Console.WriteLine(thread.Name + " terminating.");
}
}
/// <summary>
/// Description of BasicThreads_TestThreadSafety_v1a.
/// </summary>
public class BasicThreads_TestThreadSafety_v1a
{
public BasicThreads_TestThreadSafety_v1a()
{
}
public void BufferAnalyze()
{
string strCurrentBuffer = ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.ToString();
Console.WriteLine("[BufferAnalyze()] ||<< Thread 'Randomly' Slept due to comp resource scheduling");
Thread.Sleep(1000); // Simulate poor timing of thread resourcing...
ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.Length = 0;
Console.WriteLine("[BufferAnalyze()]\r\nstrCurrentBuffer[{0}] == {1}", strCurrentBuffer.Length.ToString(), strCurrentBuffer);
}
public void TestBasicThreads_TestThreadSafety_v1a()
{
Console.Write("Starting TestBasicThreads_TestThreadSafety_v1a >>> Press any key to continue . . . ");
Console.Read();
// First, construct a MyThread object.
ThreadWorker_TestThreadSafety_v1a threadWorker_TestThreadSafety_v1a = new ThreadWorker_TestThreadSafety_v1a("threadWorker_TestThreadSafety_v1a Child");
do
{
Console.WriteLine("[TestBasicThreads_TestThreadSafety_v1a()]");
Thread.Sleep(750);
BufferAnalyze();
//} while (ThreadWorker_TestThreadSafety_v1a.thread.IsAlive);
} while (threadWorker_TestThreadSafety_v1a.IsAlive);
BufferAnalyze();
Thread.Sleep(1250);
Console.WriteLine("[TestBasicThreads_TestThreadSafety_v1a()]");
Console.WriteLine("ThreadWorker_TestThreadSafety_v1a.strBuilderLog[{0}] == {1}", ThreadWorker_TestThreadSafety_v1a.strBuilderLog.Length.ToString(), ThreadWorker_TestThreadSafety_v1a.strBuilderLog);
Console.Write("Completed TestBasicThreads_TestThreadSafety_v1a >>> Press any key to continue . . . ");
Console.Read();
}
}
}
答案 0 :(得分：4)
下载3.5 Reactive Extensions的here后端。还有一个NuGet包。下载后，只需在项目中引用System.Threading.dll。
现在，您可以在.NET 3.5中使用.NET 4.0中的所有新并发集合标准。最适合您情况的是BlockingCollection。它基本上是一个缓冲区，允许线程将项排入队列并将它们像普通队列一样出列。除了出列操作阻止，直到某个项目可用。
现在根本不需要使用StringBuilder课程。这是我如何重构你的代码。我试图让我的例子简短，以便更容易理解。
public class Example
{
private BlockingCollection<string> buffer = new BlockingCollection<string>();
public Example()
{
new Thread(ReadFromExternalDevice).Start();
new Thread(BufferAnalyze).Start();
}
private void ReadFromExteneralDevice()
{
while (true)
{
string data = GetFromExternalDevice();
buffer.Add(data);
Thread.Sleep(200);
}
}
private void BufferAnalyze()
{
while (true)
{
string data = buffer.Take(); // This blocks if nothing is in the queue.
Console.WriteLine(data);
}
}
}
为了将来参考，TPL Data Flow库中的BufferBlock<T>类与BlockingCollection基本相同。它将在.NET 4.5中提供。
答案 1 :(得分：3)
使用StringBuffer不是线程安全的，但您可以切换到ConcurrentQueue<char>。
如果您需要其他数据结构，.NET 4中还有其他线程安全的集合，请参阅http://msdn.microsoft.com/en-us/library/dd997305.aspx。
编辑：在.NET 3.5中，同步原语较少。您可以通过在Queue<char>周围添加一个锁来创建一个简单的解决方案，尽管它的效率低于.NET 4的ConcurrentQueue。或者使用相同的StrignBuffer，再次使用lock读/写操作：
public static StringBuilder strBuilderBuffer = new StringBuilder("", 7500);
private object BufferLock = new object();
...
lock (BufferLock)
strBuilderBuffer.Append(strSomeData);
...
string strCurrentBuffer;
lock (BufferLock)
{
strCurrentBuffer = ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.ToString();
ThreadWorker_TestThreadSafety_v1a.strBuilderBuffer.Clear();
}
Console.WriteLine("[BufferAnalyze()] ||<< Thread 'Randomly' Slept ...");
Thread.Sleep(1000); // Simulate poor timing of thread resourcing...
编辑：
您不能保证操作系统不会挂起持有锁的工作线程。但是，只要一个线程正在处理它，锁就可以保证其他线程不会干扰并更改缓冲区。
这就是为什么你握住锁的时间应该尽可能短：
答案 2 :(得分：1)
如果你从缓冲区中读取大量内容，也许这会有所帮助：
http://msdn.microsoft.com/en-us/library/system.threading.readerwriterlock.aspx
可以使用多个读者，但只有一个作者。
它可以在.NET 1.X及以上版本中使用...