并发：线程池异步执行与创建单独的线程执行

线程池与并行度

实例代码验证

static void Main(string[] args)
{
const int numberOfOperations = 500;
var sw = new Stopwatch();
sw.Start();
UseThreads(numberOfOperations);
sw.Stop();
Console.WriteLine("Thread Execution time using threads: {0}", sw.ElapsedMilliseconds);

sw.Reset();
sw.Start();
UseThreadPool(numberOfOperations);
sw.Stop();
Console.WriteLine("ThreadPool Execution time using threads: {0}", sw.ElapsedMilliseconds);

Console.ReadKey();
}

static void UseThreads(int numberOfOperations)
{
using (var countdown = new CountdownEvent(numberOfOperations))//并发执行个数
{
Console.WriteLine("Scheduling work by creating threads");
for (int i = 0; i < numberOfOperations; i++)
{
var thread = new Thread(() => {
Console.Write("{0},", Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(TimeSpan.FromSeconds(0.1));
countdown.Signal();//注册当前线程
});
//thread.IsBackground = true;
thread.Start();
}
countdown.Wait();
Console.WriteLine();
}
}

static void UseThreadPool(int numberOfOperations)
{
using (var countdown = new CountdownEvent(numberOfOperations))//并发执行个数
{
Console.WriteLine("Starting work on a threadpool");
for (int i = 0; i < numberOfOperations; i++)
{
ThreadPool.QueueUserWorkItem( _ => {
Console.Write("{0},", Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(TimeSpan.FromSeconds(0.1));
countdown.Signal();//注册当前线程
});
}
countdown.Wait();
Console.WriteLine();
}
}

结论