我需要一个缓慢的C#函数

Question

对于我正在做的一些测试,我需要一个C#函数,大约需要10秒才能执行.它将从ASPX页面调用,但我需要在服务器上占用CPU时间的功能,而不是渲染时间.对Northwinds数据库的慢速查询会起作用,或者计算速度很慢.有任何想法吗？

Answer 1

尝试计算第n个素数以模拟CPU密集型工作 -

public void Slow()
{
    long nthPrime = FindPrimeNumber(1000); //set higher value for more time
}

public long FindPrimeNumber(int n)
{
    int count=0;
    long a = 2;
    while(count<n)
    {
        long b = 2;
        int prime = 1;// to check if found a prime
        while(b * b <= a)
        {
            if(a % b == 0)
            {
                prime = 0;
                break;
            }
            b++;
        }
        if(prime > 0)
        {
            count++;
        }
        a++;
    }
    return (--a);
}

需要多长时间取决于系统的硬件配置.

因此尝试输入为1000然后增加输入值或减少它.

此功能将模拟CPU密集型工作.

Answer 2

Arguably the simplest such function is this:

public void Slow()
{
    var end = DateTime.Now + TimeSpan.FromSeconds(10);
    while (DateTime.Now < end)
           /*nothing here */ ;
}

Answer 3

You can use a 'while' loop to make the CPU busy.

    void CpuIntensive()
    {
        var startDt = DateTime.Now;

        while (true)
        {
            if ((DateTime.Now - startDt).TotalSeconds >= 10)
                break;
        }
    }

此方法将在while循环中保持10秒.此外,如果在多个线程中运行此方法,则可以使所有CPU核心忙碌.

Answer 4

为了最大化多个核心,我调整了@ Motti的答案,得到了以下结果:

Enumerable
  .Range(1, Environment.ProcessorCount) // replace with lesser number if 100% usage is not what you are after.
  .AsParallel()
  .Select(i => {
    var end = DateTime.Now + TimeSpan.FromSeconds(10);
    while (DateTime.Now < end)
      /*nothing here */ ;
    return i;
  })
  .ToList(); // ToList makes the query execute.

Answer 5

This is CPU intensive on a single thread/CPU, and lasts 10 seconds.

var endTime = DateTime.Now.AddSeconds(10);

while(true) {
   if (DateTime.Now >= endTime) 
      break;
}

As a side note, you should not normally do this.