这是我编写的用于测试基本线程场景的程序。当我在启用调试的情况下运行它时,它完全按预期工作。
using System;
using System.Threading;
class Program
{
static bool keepCounting;
static void Main(string[] args)
{
Thread myThread = new Thread(countNumbers);
myThread.Name = "MyThread";
keepCounting = true;
myThread.Start();
Thread.Sleep(new TimeSpan(0, 0, 1)); // countNumbers() runs for 1 sec.
keepCounting = false;
}
static void countNumbers()
{
Console.WriteLine("{0} beginning count.", Thread.CurrentThread.Name);
long n = 0;
while (keepCounting)
{
n++;
}
Console.WriteLine("Current thread: {0}", Thread.CurrentThread.Name);
Console.WriteLine("Number of iterations: {0}", n);
}
}
然而,当我设置VS进行发布构建,并使用“Start Without Debugging”运行它时 - 请注意,必须采取这些步骤,否则它仍然会成功 - 它会神秘地“卡住” “在打印”MyThread开始计数后“countNumbers()
方法中间某处,它永远不会超时并将结果打印到控制台窗口。
任何人都可以解释这种古怪的行为吗?
答案 0 :(得分:3)
你的循环
while (keepCounting)
{
n++;
}
就语言而言,是等同于
var cpu_register = keepCounting;
while (cpu_register)
{
n++;
}
CPU寄存器比内存读取快得多,因此优化器使用第二个版本。可预测的不愉快结果。