C#多线程与异步/等待结合 [英] C# multithreading combined with async/await
问题描述
这是与C#中的多线程有关的另一个问题.
This is yet another question related to multi-threading in C#.
但是,将多线程与async/await结合使用似乎很有趣.
However, when multi-threading combined with async/await seems to be interesting.
我有一个生成线程的方法,该线程异步调用对象的方法.
I have a method generating threads which invoke methods of objects asynchronously.
但是,上下文不是由不同类的对象共享的.
However, the context is not shared by objects of different classes.
例如,考虑代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ThreadDataSharing
{
class Data
{
public static ThreadLocal<string> Name = new ThreadLocal<string>();
}
class Locker { public static object lobj = new object { };}
class Program2
{
static void Main(string[] args)
{
for (int i = 0; i < 3; i++)
{
var pObj = new Program();
new Thread(new ThreadStart(pObj.MyThreadMethod)).Start();
}
}
}
class Program
{
///my async method
///
public async Task MyAsyncMethod()
{
lock (Locker.lobj)
{
Console.WriteLine("From async method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("id: " + Data.Name.Value);
}
await MyAsyncMethod2();
await new AsyncClass().AsyncMethod();
}
public async Task MyAsyncMethod2()
{
lock (Locker.lobj)
{
Console.WriteLine("From async 2 method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("id: " + Data.Name.Value);
}
await Task.Run(() =>
{
lock (Locker.lobj)
{
Console.WriteLine("From task run method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("id: " + Data.Name.Value);
}
});
}
public void MyThreadMethod()
{
lock (Locker.lobj)
{
Console.WriteLine("From thread method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
var id = Guid.NewGuid();
Data.Name.Value = id.ToString();
Console.WriteLine("id: " + Data.Name.Value);
}
MyAsyncMethod().Wait();
}
}
public class AsyncClass
{
public async Task AsyncMethod()
{
lock (Locker.lobj)
{
Console.WriteLine("From class async method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("id: " + Data.Name.Value);
}
var newId = Guid.NewGuid();
Data.Name.Value = newId.ToString();
await AsyncMethod2();
}
public async Task AsyncMethod2()
{
lock (Locker.lobj)
{
Console.WriteLine("From class async 2 method");
Console.WriteLine("thread: " + Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("id: " + Data.Name.Value);
}
await Task.Run(() => { });
}
}
}
运行此代码会在我的机器上产生以下输出
Running this code produces the following output on my machine
From thread method
thread: 3
id: 3a7ef8e3-ebe1-49e1-94bb-798358ac1567
From thread method
thread: 4
id: 341d3371-f905-4e1c-aac3-47bda16c8d88
From thread method
thread: 5
id: b7e79901-81b7-430f-b158-59f091e43a0c
From async method
thread: 3
id: 3a7ef8e3-ebe1-49e1-94bb-798358ac1567
From async method
thread: 5
id: b7e79901-81b7-430f-b158-59f091e43a0c
From async method
thread: 4
id: 341d3371-f905-4e1c-aac3-47bda16c8d88
From async 2 method
thread: 3
id: 3a7ef8e3-ebe1-49e1-94bb-798358ac1567
From async 2 method
thread: 4
id: 341d3371-f905-4e1c-aac3-47bda16c8d88
From async 2 method
thread: 5
id: b7e79901-81b7-430f-b158-59f091e43a0c
From task run method
thread: 6
id:
From task run method
thread: 8
id:
From task run method
thread: 7
id:
From class async method
thread: 7
id:
From class async method
thread: 6
id:
From class async method
thread: 8
id:
From class async 2 method
thread: 8
id: f52ed654-0e55-4906-bfc1-65c6b25a7785
From class async 2 method
thread: 7
id: 1e53e03b-a3a0-4296-8622-7716b45d1462
From class async 2 method
thread: 6
id: 1adca81d-b11a-4860-b37d-a017afe877b8
问题是,为什么它不与第二个类( AsyncClass
)的实例共享 ThreadLocal< T>
对象?
Question is, why is it not sharing the ThreadLocal<T>
object with the instance of the second Class (AsyncClass
)?
推荐答案
在具有await/async的控制台应用程序中,没有共享的同步上下文,这可能就是为什么它不共享的原因.
In a Console app with await/async there isn't shared synchronization context, may be this is the reason why it's not shared.
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