Question

我正在尝试创建一个日志库，在调用应用程序关闭之前一切正常。调用应用程序关闭时，任何未完成的线程都将被终止，特定日志将丢失。

截至目前，应用程序甚至在前10个线程完成之前就退出了。我想要了解如何使应用程序等到库创建的所有线程完成之后的帮助。

注意：我得到的要求是这样的。修改应仅在“Logging”类中，因为这将是一个库，并将提供给最终用户。在app关闭期间处理日志记录问题必须在其中完成。这是我现在遇到麻烦的地方。

或者像在日志记录类中创建事件以触发所有日志记录完成的解决方案，并要求用户在该事件上调用app exit是可能的，但我试图避免，因为它给最终用户增加了负担并增加了复杂性用于实现。他们有可能跳过它，我不想要。我正在寻找一个像用户应该做'Logging.AddException（....）'的解决方案，然后忘了它。

请帮忙。如果您不清楚这个想法，请提供意见。

以下是可以放入控制台应用程序的完整代码摘要。 注意：在CASE 1和CASE 2中查找评论。

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace MultithreadKeepAlive
{
class Program
{
    static void Main(string[] args)
    {
        LogLoadTest();
        Logging.AddExceptionEntryAsync(new Exception("Last Exception"));

        /*
         * USE CASE 1: Enable the below lines and you will see how long it is supposed to take.
         * Notice that currentDomain_ProcessExit will not trigger if below gets uncommented
         */
        //Console.WriteLine("Main thread wait override");
        //Console.ReadLine();
    }

    static void LogLoadTest()
    {
        //In real world this will be called from any place of application like startup or just after application shutdown is initiated.
        //: NOTICE: Unlike the sample here, this will never be on loop and I am not looking for handling multithreads in this class.
        //      That responsibility I am planning to assign to Logging class.
        // AND ALSO the class Logging is going to be in a seperate signed assembly where user of this class ('Program') should not worry about multithreads.
        Task t;
        for (int i = 0; i < 40; i++)
        {
           t =  Logging.AddExceptionEntryAsync(new Exception("Hello Exception " + i), "Header info" + i);
        }
    }
}

public class Logging
{
    static List<Task> tasks = new List<Task>();

    static AppDomain currentDomain;
    static Logging()
    {
        currentDomain = AppDomain.CurrentDomain;
        currentDomain.ProcessExit += currentDomain_ProcessExit;
    }

    public static async Task AddExceptionEntryAsync(Exception ex, string header = "")
    {
        Task t = Task.Factory.StartNew(() => AddExceptionEntry(ex, header));
        tasks.Add(t);
        await t;
    }

    public static void AddExceptionEntry(Exception ex, string header)
    {
        /* Exception processing and write to file or DB. This might endup in file locks or 
         * network or any other cases where it will take delays from 1 sec to 5 minutes. */
        Thread.Sleep(new Random().Next(1, 1000));
        Console.WriteLine(ex.Message);
    }

    static void currentDomain_ProcessExit(object sender, EventArgs e)
    {
            Console.WriteLine("Application shutdown triggerd just now.");
            Process.GetCurrentProcess().WaitForExit();    //1st attempt.
            //Task.WaitAll(tasks.ToArray()); //2nd attempt
            while (tasks.Any(t => !t.IsCompleted)) //3rd attempt.
            {
            }
            /* USE CASE 2: IF WORKING GOOD, THIS WILL BE DISPLAYED IN CONSOLE AS LAST 
             * MESSAGE OF APPLICATION AND WILL WAIT FOR USER. THIS IS NOT WORKING NOW.*/
            Console.WriteLine("All complete"); //this message should show up if this work properly
            Console.ReadLine(); //for testing purpose wait for input from user after every thread is complete. Check all 40 threads are in console.
    }
}

}

Answer 1

截至目前，我自己找到了解决方法。

    /// <summary>
    /// Makes the current thread Wait until any of the pending messages/Exceptions/Logs are completly written into respective sources.
    /// Call this method before application is shutdown to make sure all logs are saved properly.
    /// </summary>
    public static void WaitForLogComplete()
    {
        Task.WaitAll(tasks.Values.ToArray());
    }

Answer 2

你可以尝试

Task.WaitAll(tasks);

等待所有提供的Task对象完成执行。

更新：使用async / await

使用async和await，我们正式化并阐明异步，非阻塞方法的开始和结束方式。异步方法只能返回void或任务。

static void Main()
{
// Create task and start it.
// ... Wait for it to complete.
Task task = new Task(AsyncMethod);
task.Start();
task.Wait();
}

public static async void AsyncMethod(){
await AnotherMehod();}

static async Task AnotherMehod() { //TODO}

Answer 3

步骤1：如果您不想让调度程序参与，请考虑更改为Task.Run（）。我还假设您要等到所有异步任务完成。

public static AddExceptionEntry(Exception ex, string header = "")
{
    Task t = Task.Factory.StartNew(() => AddExceptionEntry(ex, header));
    tasks.Add(t);

    WaitForExecutionAsync().ConfigureAwait(true);
}

public static async Task WaitForExecutionAsync()
{
    if(tasks.Count >0) 
        await Task.WhenAll(tasks.ToArray());
    // Raise Event.
}

阻止只是调用它来运行sync vs async：

WaitForExecution().GetAwaiter().GetResult();

C＃.Net - 如何让应用程序等到在Library中创建的所有线程完成之后

3 个答案: