C#有ThreadPool和Task，为什么还要自己写线程池？我以前也没想过自己写线程池，都是用ThreadPool或Task，前段时间写爬虫，我想控制10个线程爬网页、10个线程下载网页上的图片，不然的话因为网页很多，图片相对较少，可能大部分线程都在爬网页，少量线程在下载图片，这样下载图片的速度慢了，所以我想到了自己写线程池MyThreadPool，再配合ThreadPool使用，精确控制爬网页和下载图片的线程数。不过这个线程池写的比较简单，缺点是线程池会瞬间创建最大数量的工作线程。
线程池类代码：
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace Utils
{
/// <summary>
/// 线程池
/// </summary>
public static class MyThreadPool
{
/// <summary>
/// 最大工作线程数
/// </summary>
private static int m_WorkerThreads = 5;
/// <summary>
/// 线程队列
/// </summary>
private static ConcurrentQueue<MyThread> m_ThreadQueue = new ConcurrentQueue<MyThread>();
/// <summary>
/// 任务队列
/// </summary>
private static ConcurrentQueue<Tuple<Action<object>, object>> m_Action = new ConcurrentQueue<Tuple<Action<object>, object>>();
/// <summary>
/// 创建并启动线程
/// </summary>
/// <param name="action"></param>
/// <param name="obj"></param>
public static void Start(Action<object> action, object obj = null)
{
m_Action.Enqueue(new Tuple<Action<object>, object>(action, obj));
MyThread thread;
if (m_ThreadQueue.Count < m_WorkerThreads)
{
thread = new MyThread();
m_ThreadQueue.Enqueue(thread);
thread.isWorker = true; //设置为工作线程
thread.thread = new Thread(new ThreadStart(() =>
{
Tuple<Action<object>, object> tuple;
while (thread.isWorker) //如果是工作线程，则一直循环
{
if (m_Action.TryDequeue(out tuple)) //如果任务队列中有任务，则取出任务执行
{
tuple.Item1(tuple.Item2); //执行任务
}
else
{
Thread.Sleep(100);
}
Thread.Sleep(1);
}
}));
thread.thread.IsBackground = true;
thread.thread.Start();
}
}
/// <summary>
/// 设置最大工作线程数
/// </summary>
/// <param name="workerThreads">最大工作线程数</param>
public static void SetMaxThreads(int workerThreads)
{
m_WorkerThreads = workerThreads;
MyThread thread = null;
while (m_ThreadQueue.Count > m_WorkerThreads)
{
m_ThreadQueue.TryDequeue(out thread);
thread.isWorker = false;
Thread.Sleep(1);
}
}
/// <summary>
/// 获取最大工作线程数
/// </summary>
public static int GetMaxThreads()
{
return m_WorkerThreads;
}
/// <summary>
/// 获取当前工作线程数
/// </summary>
public static int GetWorkerThreads()
{
return m_ThreadQueue.Count;
}
}
/// <summary>
/// 线程
/// </summary>
public class MyThread
{
/// <summary>
/// 线程
/// </summary>
public Thread thread { get; set; }
/// <summary>
/// 是否工作线程
/// </summary>
public bool isWorker { get; set; }
}
}
测试代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using Common.Utils;
using System.Collections.Concurrent;
namespace test
{
public partial class Form1 : Form
{
private static int errorCount = 0;
private static int errorCount2 = 0;
private static object _lock = new object();
private static int dataCount = 30;
/// <summary>
/// 任务执行总次数
/// </summary>
private static int runCount = 0;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
ThreadPool.SetMaxThreads(20, 20);
StringBuilder sb = new StringBuilder();
for (int k = 1; k <= dataCount; k++)
{
sb.AppendFormat("{0},", k.ToString("00"));
}
lblMsg2.Text = sb.ToString();
timer1.Tick += new EventHandler((obj, ea) =>
{
int maxThreads = MyThreadPool.GetMaxThreads();
int workerThreads = MyThreadPool.GetWorkerThreads();
lblMsg.Text = string.Format("{0}/{1}(工作线程数/最大工作线程数)", workerThreads, maxThreads);
//ThreadPool.GetMaxThreads(out workerThreads, out maxThreads);
//lblMsg.Text = string.Format("{0}/{1}(最大辅助线程数/最大I/O线程数)", workerThreads, maxThreads);
if (workerThreads > maxThreads)
{
errorCount++;
lblError.Text = "错误(工作线程数超过最大工作线程数)次数：" + errorCount.ToString() + "，错误(线程内代码执行结果错误)次数：" + errorCount2.ToString();
}
if (lblMsg2.Text != sb.ToString())
{
errorCount2++;
lblError.Text = "错误(工作线程数超过最大工作线程数)次数：" + errorCount.ToString() + "，错误(线程内代码执行结果错误)次数：" + errorCount2.ToString();
LogUtil.LogError(lblMsg2.Text);
}
lblRunCount.Text = "任务执行总次数：" + runCount.ToString();
});
timer1.Interval = 100;
timer1.Start();
lblError.Text = "暂没有错误";
}
//开始
private void button1_Click(object sender, EventArgs e)
{
MyThreadPool.SetMaxThreads(20);
ThreadPool.SetMaxThreads(20, 20);
button1.Enabled = false;
Thread thread = new Thread(new ThreadStart(() =>
{
while (true)
{
List<int> list = new List<int>();
for (int i = 1; i <= dataCount; i++)
{
// ThreadPool.QueueUserWorkItem((obj) =>
// Task.Factory.StartNew((obj) =>
MyThreadPool.Start((obj) =>
{
int n = (int)obj;
lock (_lock)
{
list.Add(n);
}
if (list.Count == dataCount)
{
list.Sort();
StringBuilder sb = new StringBuilder();
for (int k = 0; k < list.Count; k++)
{
sb.AppendFormat("{0},", list[k].ToString("00"));
}
this.Invoke(new MyInvoke(() => { lblMsg2.Text = sb.ToString(); }));
runCount++;
}
}, i);
}
Thread.Sleep(1);
}
}));
thread.IsBackground = true;
thread.Start();
}
//设置最大工作线程数
private void button2_Click(object sender, EventArgs e)
{
int d;
if (int.TryParse(txtMaxThreads.Text, out d))
{
if (d > 0)
{
MyThreadPool.SetMaxThreads(d);
ThreadPool.SetMaxThreads(d, d);
}
else
{
txtMaxThreads.Text = "1";
}
}
else
{
txtMaxThreads.Text = "20";
}
}
}
public delegate void MyInvoke();
}
测试截图：
来源：https://www.cnblogs.com/s0611163/p/6178973.html