threadpool 里的线程可以不退出吗（C多线程）
threadpool 里的线程可以不退出吗（C多线程）Dead 任务完成后，处于死亡或终止状态Not Runable 非运行状态，调用了sleep、wait或I/O被阻塞UnStarted 处于创建但未启动状态Runnable 调用了start，处于可运行或准备运行状态Running 运行中状态
线程和进程进程：进程包含一个程序运行所需要的资源，进程即是一个程序，一个进程可以有多个线程。
线程：操作系统能够进行运算调度的最小单位。
Windows 任务管理器
进程可以有多个线程。
生命周期UnStarted 处于创建但未启动状态
Runnable 调用了start，处于可运行或准备运行状态
Running 运行中状态
Not Runable 非运行状态，调用了sleep、wait或I/O被阻塞
Dead 任务完成后，处于死亡或终止状态
ThreadThread 常用属性
class Program
{
static void Main(string[] args)
{
Console.WriteLine("主线程:" Thread.CurrentThread.ManagedThreadId);
Thread t = new Thread(new ThreadStart(Thread_A));
Console.WriteLine("创建线程 -- 线程状态：" t.ThreadState);
t.Start();
Thread.Sleep(1000); // 睡眠1秒
Console.ReadKey();
}
private static void Thread_A()
{
Console.WriteLine("常用属性值：");
Console.WriteLine("当前运行线程实例:" Thread.CurrentThread);
Console.WriteLine("当前线程唯一ID:" Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("当前线程名称:" Thread.CurrentThread.Name);
Console.WriteLine("当前线程优先级:" Thread.CurrentThread.Priority);
Console.WriteLine("当前线程状态:" Thread.CurrentThread.ThreadState);
Console.WriteLine("当前线程是否处于活跃:" Thread.CurrentThread.IsAlive);
Console.WriteLine("当前线程是否为后台线程:" Thread.CurrentThread.IsBackground);
/*
前台线程：主程序必须等待线程执行完毕后才能退出程序
后台线程：主程序执行完毕后就退出，不管线程是否完成
*/
}
}
输出
Thread 优先级
class Program
{
static void Main(string[] args)
{
Thread t1 = new Thread(new ThreadStart(A));
t1.Start();
Thread t2 = new Thread(new ThreadStart(B));
t2.Start();
Thread t3 = new Thread(new ThreadStart(C));
t3.Start();
Console.ReadKey();
}
private static void A()
{
Console.WriteLine("A");
}
private static void B()
{
Console.WriteLine("B");
}
private static void C()
{
Console.WriteLine("C");
}
}
第一次输出：ABC
第二次输出：BAC
第三次输出：ABC
第四次输出：ACB
第四次输出
Thread 优先级相同时没有先后顺序，设置优先级：
class Program
{
static void Main(string[] args)
{
Thread t1 = new Thread(new ThreadStart(A));
t1.Start();
t1.Priority = ThreadPriority.Highest;
Thread t2 = new Thread(new ThreadStart(B));
t2.Start();
t2.Priority = ThreadPriority.Highest;
Thread t3 = new Thread(new ThreadStart(C));
t3.Start();
t3.Priority = ThreadPriority.Highest;
Thread t4 = new Thread(new ThreadStart(D));
t4.Start();
Console.ReadKey();
}
private static void A()
{
Console.WriteLine("A");
}
private static void B()
{
Console.WriteLine("B");
}
private static void C()
{
Console.WriteLine("C");
}
private static void D()
{
Console.WriteLine("D");
}
}
第一次输出：CABD
第二次输出：ABCD
第三次输出：ACBD
第四次输出：ACBD
D的优先级最低，ABC优先级都是 Highest 同优先级不分顺序
带参 Threadclass Program
{
static void Main(string[] args)
{
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
Thread t1 = new Thread(new ParameterizedThreadStart(A)); // 带参数的方法
t1.Start("ThreadTest"); // 传参
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
Console.ReadLine();
}
private static void A(object data)
{
Console.WriteLine("Message: " data " 标识：" Thread.CurrentThread.ManagedThreadId);
}
}
输出
Thread 线程阻塞Thread.Join() 可以阻塞主线程
class Program
{
static void Main(string[] args)
{
Thread t1 = new Thread(() => { Console.WriteLine("A"); });
t1.Start();
t1.Join();
Console.WriteLine("主线程");
Console.Read();
}
}
输出
阻塞所有线程，t1 执行完成之后再执行其他线程
Thread.Sleep(); 阻塞当前线程
class Program
{
static void Main(string[] args)
{
Thread t1 = new Thread(() =>
{
Console.WriteLine("A");
Thread.Sleep(1000);
});
t1.Start();
Console.WriteLine("主线程");
Console.Read();
}
}
输出
当前线程阻塞1s，Thread.Sleep() 单位是ms
Thread 方法
来源：https://www.lidihuo.com/csharp/csharp-thread-class.html
Lock 线程锁例：A、B同时在银行取钱，余额只有1000，两人都需要取1000，A取出来1000后，B取得时候提示余额不足
class Program
{
private static object obj = new object();
private static int money = 1000;
static void Main(string[] args)
{
Thread thread1 = new Thread(Sum1);
thread1.Start();
Thread thread2 = new Thread(Sum1);
thread2.Start();
Console.ReadKey();
}
public static void Sum1()
{
lock (obj)
{
if(money >= 1000)
{
money -= 1000;
Console.WriteLine("余额：{0}" money);
}
else
{
Console.WriteLine("余额不足");
}
}
}
}
输出
ThreadPoolThreadPool 线程池是为了方便对线程进行管理，线程池可以限制线程数量且可以重复使用
static void Main(string[] args)
{
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
ThreadPool.QueueUserWorkItem(p => A("")); // A括号里面传参数
ThreadPool.QueueUserWorkItem(new WaitCallback(A));
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
Console.ReadLine();
}
private static void A(object data)
{
Console.WriteLine("Message: " data " 标识：" Thread.CurrentThread.ManagedThreadId);
}
输出
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
Thread t1 = new Thread(new ThreadStart(A));
Thread t2 = new Thread(new ThreadStart(B));
t1.Start();
t2.Start();
Console.WriteLine("Main 标识：" Thread.CurrentThread.ManagedThreadId);
Console.ReadLine();
}
private static void B()
{
Console.WriteLine("Thread B");
}
private static void A()
{
Console.WriteLine("Thread A");
}
}
输出
两端代码运行过多次，Thread 主线程会等待线程，ThreadPool 主线程不会等待线程
ThreadPool 线程重用、线程数量线程数量
class Program
{
static void Main(string[] args)
{
int workerThreads; // 工作线程
int completionPortThreads; // I/O 线程
ThreadPool.GetMaxThreads(out workerThreads out completionPortThreads);
Console.WriteLine($"最大线程数：{workerThreads} {completionPortThreads}");
ThreadPool.GetMinThreads(out workerThreads out completionPortThreads);
Console.WriteLine($"最小线程数：{workerThreads} {completionPortThreads}");
Console.ReadLine();
}
}
输出
设置数量
class Program
{
static void Main(string[] args)
{
int workerThreads; // 工作线程
int completionPortThreads; // I/O 线程
// 设置最大线程
ThreadPool.SetMaxThreads(5 5);
// 设置最小线程
ThreadPool.SetMinThreads(1 1);
ThreadPool.GetMaxThreads(out workerThreads out completionPortThreads);
Console.WriteLine($"最大线程数：{workerThreads} {completionPortThreads}");
ThreadPool.GetMinThreads(out workerThreads out completionPortThreads);
Console.WriteLine($"最小线程数：{workerThreads} {completionPortThreads}");
Console.ReadLine();
}
}
输出
线程重用
class Program
{
static void Main(string[] args)
{
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
ThreadPool.QueueUserWorkItem(new WaitCallback(GetMoney));
Console.ReadKey();
}
private static void GetMoney(object state)
{
Console.WriteLine("线程标识: " Thread.CurrentThread.ManagedThreadId);
}
}
输出
从输出的线程标识中可以看出只用了三个线程，减少了线程的创建
带参 ThreadPoolclass Program
{
static void Main(string[] args)
{
string msg = "The User Does't exit";
object mg = "Hello Banananana";
ThreadPool.QueueUserWorkItem((a) => Message(msg));
ThreadPool.QueueUserWorkItem(new WaitCallback(Message) mg); // 传参类型需要 Object
Console.Read();
}
private static void Message(string msg)
{
Console.WriteLine(msg);
}
private static void Message(object msg)
{
Console.WriteLine(msg "");
}
}
输出
QueueUserWorkItem
回调方法
TaskThreadPool 不能控制线程执行的顺序，也不能获取线程池内线程的取消、异常、完成的通知
Task 无返回值线程class Program
{
static void Main(string[] args)
{
Console.WriteLine("开始执行");
var factory = new TaskFactory();
Task t1 = factory.StartNew(() => Console.WriteLine("A，标识: {0}" Thread.CurrentThread.ManagedThreadId));
Task t2 = Task.Factory.StartNew(() => Console.WriteLine("B，标识: {0}" Thread.CurrentThread.ManagedThreadId));
Task t3 = new Task(() => Console.WriteLine("C，标识: {0}" Thread.CurrentThread.ManagedThreadId));
t3.Start();
Task t4 = Task.Run(() => Console.WriteLine("D，标识: {0}" Thread.CurrentThread.ManagedThreadId));
Console.Read();
}
}
输出
Task 有返回值线程class Program
{
static void Main(string[] args)
{
Task<string> t1 = new Task<string>(() => { return $"A 标识:{Thread.CurrentThread.ManagedThreadId}"; });
t1.Start();
Task<string> t2 = Task.Factory.StartNew(() => { return $"B 标识:{Thread.CurrentThread.ManagedThreadId}"; });
Task<string> t3 = Task.Run(() => { return $"C 标识:{Thread.CurrentThread.ManagedThreadId}"; });
Console.WriteLine(t1.Result);
Console.WriteLine(t2.Result);
Console.WriteLine(t3.Result);
Console.Read();
}
}
输出
注：Task.Result 返回结果时会阻塞线程
Task 同步执行class Program
{
static void Main(string[] args)
{
Task t1 = new Task(() => Console.WriteLine("Task 线程"));
t1.RunSynchronously(); // 同步方法
Console.WriteLine("主线程");
Console.Read();
}
}
输出
Task 线程阻塞Thread 也有方法可以进行阻塞，但每次只能对一个线程进行阻塞，Task 可以有方法可以解决这个问题，task.Wait() 等待 task 执行完成，类似 Thread.Join()，Task.WaitAll() 执行完所有 task 再解除线程，Task.WaitAny() 只要有一个 task 执行完成就解除线程
Task.Wait
class Program
{
static void Main(string[] args)
{
Task t1 = new Task(() => { Console.WriteLine("A"); });
t1.Start();
t1.Wait();
Console.WriteLine("主线程");
Console.Read();
}
}
Task.Wait()
阻塞所有线程，等待当前执行完成
Task.WaitAll
class Program
{
static void Main(string[] args)
{
List<Task> list = new List<Task>();
Task t1 = Task.Run(() => Console.WriteLine("A"));
Task t2 = Task.Run(() => Console.WriteLine("B"));
Task t3 = Task.Run(() => Console.WriteLine("C"));
Task t4 = Task.Run(() => Console.WriteLine("D"));
list.Add(t1);
list.Add(t2);
list.Add(t3);
list.Add(t4);
Task.WaitAll(list.ToArray());
Console.WriteLine("主线程");
Console.Read();
}
}
Task.WaitAll
等待 Task线程组 完成
Task.WaitAny
class Program
{
static void Main(string[] args)
{
List<Task> list = new List<Task>();
Task t1 = Task.Run(() => Console.WriteLine("A"));
Task t2 = Task.Run(() => Console.WriteLine("B"));
Task t3 = Task.Run(() => Console.WriteLine("C"));
Task t4 = Task.Run(() => Console.WriteLine("D"));
list.Add(t1);
list.Add(t2);
list.Add(t3);
list.Add(t4);
Task.WaitAny(list.ToArray());
Console.WriteLine("主线程");
Console.Read();
}
}
Task.WaitAny
线程组任意线程完成就接触阻塞
Task 延续操作有一个需求，需要在 task 线程组 执行完成之后执行
class Program
{
static void Main(string[] args)
{
List<Task> list = new List<Task>();
Task t1 = Task.Run(() => Console.WriteLine("A"));
Task t2 = Task.Run(() => Console.WriteLine("B"));
Task t3 = Task.Run(() => Console.WriteLine("C"));
Task t4 = Task.Run(() => Console.WriteLine("D"));
list.Add(t1);
list.Add(t2);
list.Add(t3);
list.Add(t4);
// 二选一即可
Task.WhenAll(list.ToArray()).ContinueWith(t => Console.WriteLine("执行完成"));
// Task.Factory.ContinueWhenAll(list.ToArray() t => Console.WriteLine("执行完成"));
Console.WriteLine("主线程");
Console.Read();
}
}
输出
从输出中可以看出，task 不会阻塞主线程
有一个需求，需要在 task 线程任意线程执行完成之后执行
class Program
{
static void Main(string[] args)
{
List<Task> list = new List<Task>();
Task t1 = Task.Run(() => Console.WriteLine("A"));
Task t2 = Task.Run(() => Console.WriteLine("B"));
Task t3 = Task.Run(() => Console.WriteLine("C"));
Task t4 = Task.Run(() => Console.WriteLine("D"));
list.Add(t1);
list.Add(t2);
list.Add(t3);
list.Add(t4);
// 二选一即可
Task.WhenAny(list.ToArray()).ContinueWith(t => Console.WriteLine("执行完成"));
// Task.Factory.ContinueWhenAny(list.ToArray() t => Console.WriteLine("执行完成"));
Console.WriteLine("主线程");
Console.Read();
}
}
输出
这个方法也不会阻塞主线程
Task 任务取消有一个下载任务已运行，但这个文件已经不需要了，需要取消这个下载任务
class Program
{
static void Main(string[] args)
{
var cts = new CancellationTokenSource();
int i;
Task t1 = new Task(() =>
{
i = 0;
while (!cts.IsCancellationRequested)
{
Thread.Sleep(1000);
Console.WriteLine($"下载中：{i }%");
if(cts.IsCancellationRequested)
Console.WriteLine("下载已取消");
}
});
t1.Start();
// cts.Cancel(); // 立刻取消
cts.CancelAfter(1000 * 10); // 10秒后取消
Console.Read();
}
}
输出
除了使用 if 语句输出 下载已取消，CancellationTokenSource 也有一个自带的注册任务取消事件
class Program
{
static void Main(string[] args)
{
var cts = new CancellationTokenSource();
int i;
Task t1 = new Task(() =>
{
i = 0;
while (!cts.IsCancellationRequested)
{
Thread.Sleep(1000);
Console.WriteLine($"下载中：{i }%");
}
});
// 取消后执行
cts.Token.Register(() =>
{
Console.WriteLine("下载已取消");
});
t1.Start();
cts.CancelAfter(1000 * 10);
Console.Read();
}
}
输出
异步方法(async/await)class Program
{
static void Main(string[] args)
{
Console.WriteLine(GetContentAsync().Result);
Console.Read();
}
// 不会阻塞线程
async static Task<string> GetContentAsync()
{
Encoding GB2312 = Encoding.GetEncoding("GB2312");
Encoding GBK = Encoding.GetEncoding("GBK");
FileStream fs = new FileStream(@"D:\1.txt" FileMode.Open);
byte[] bytes = new byte[fs.Length];
Console.WriteLine("开始读取文件");
int len = await fs.ReadAsync(bytes 0 bytes.Length);
string res = Encoding.UTF8.GetString(bytes);
return res;
}
}
输出
Task 对ThreadPool做了封装，主要是为了更好地控制线程池中的线程
完！坚持and放弃，我选择坚持
