C#避免同时读取和写入数据
示例
有时，您希望线程同时共享数据。发生这种情况时，重要的是要了解代码并锁定可能出错的任何部分。下面显示了两个线程计数的简单示例。
这是一些危险的（不正确的）代码：
using System.Threading;
class MainClass
{
static int count { get; set; }
static void Main()
{
for (int i = 1; i <= 2; i++)
{
var thread = new Thread(ThreadMethod);
thread.Start(i);
Thread.Sleep(500);
}
}
static void ThreadMethod(object threadNumber)
{
while (true)
{
var temp = count;
System.Console.WriteLine("Thread " + threadNumber + ": Reading the value of count.");
Thread.Sleep(1000);
count = temp + 1;
System.Console.WriteLine("Thread " + threadNumber + ": Incrementing the value of count to:" + count);
Thread.Sleep(1000);
}
}
}您会注意到，我们没有计算1,2,3,4,5...，而是计算1,1,2,2,3...
要解决此问题，我们需要锁定count的值，以便多个不同的线程无法同时对其进行读写。通过添加锁和钥匙，我们可以防止线程同时访问数据。
using System.Threading;
class MainClass
{
static int count { get; set; }
static readonly object key = new object();
static void Main()
{
for (int i = 1; i <= 2; i++)
{
var thread = new Thread(ThreadMethod);
thread.Start(i);
Thread.Sleep(500);
}
}
static void ThreadMethod(object threadNumber)
{
while (true)
{
lock (key)
{
var temp = count;
System.Console.WriteLine("Thread " + threadNumber + ": Reading the value of count.");
Thread.Sleep(1000);
count = temp + 1;
System.Console.WriteLine("Thread " + threadNumber + ": Incrementing the value of count to:" + count);
}
Thread.Sleep(1000);
}
}
}