[英]c# multiple threads waiting for a ManualResetEvent
我搞砸了多線程並制作了某種任務引擎。 這個想法是,引擎可以等待可配置數量的線程,並且當一個新任務到達時,第一個空閑線程將其拾取並執行。
問題是2個線程以某種方式承擔了相同的任務。 我仔細檢查了一下,認為該代碼應該可以工作,但顯然不行。 如果我在現在注釋掉的地方添加10ms睡眠,它將起作用,但是我不確定我為什么會這樣。 看起來.Reset()函數在實際重置事件之前返回了嗎?
有人可以解釋嗎? 在有多個等待時,是否有更好的方法讓僅一個線程繼續運行?
謝謝
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace TaskTest
{
public class Engine
{
private ManualResetEvent taskEvent;
private ConcurrentQueue<Task> tasks;
private bool running;
private List<Thread> threads;
private int threadAmount;
private int threadsBusy = 0;
public Engine(int amountOfThreads)
{
taskEvent = new ManualResetEvent(false);
tasks = new ConcurrentQueue<Task>();
threads = new List<Thread>();
threadAmount = amountOfThreads;
}
public void Start()
{
running = true;
for (var i = 0; i < threadAmount; i++)
{
var thread = new Thread(Process);
thread.Name = "Thread " + i;
threads.Add(thread);
thread.Start();
}
}
public void Stop()
{
running = false;
taskEvent.Set();
threads.ForEach(t => t.Join());
}
private void Process()
{
while (running)
{
lock (taskEvent)
{
// Lock it so only a single thread is waiting on the event at the same time
taskEvent.WaitOne();
taskEvent.Reset();
//Thread.Sleep(10);
}
if (!running)
{
taskEvent.Set();
return;
}
threadsBusy += 1;
if (threadsBusy > 1)
Console.WriteLine("Failed");
Task task;
if (tasks.TryDequeue(out task))
task.Execute();
threadsBusy -= 1;
}
}
public void Enqueue(Task t)
{
tasks.Enqueue(t);
taskEvent.Set();
}
}
}
編輯其余代碼:
namespace TaskTest
{
public class Start
{
public static void Main(params string[] args)
{
var engine = new Engine(4);
engine.Start();
while (true)
{
Console.Read();
engine.Enqueue(new Task());
}
}
}
}
namespace TaskTest
{
public class Task
{
public void Execute()
{
Console.WriteLine(Thread.CurrentThread.Name);
}
}
}
在按鍵上使用Console.Read()
時,將從輸入中讀取兩個字符。 您應該改用Console.ReadLine()
。
請注意,使用BlockingCollection
處理同步可以大大簡化代碼:
public class Engine
{
private BlockingCollection<Task> tasks;
private List<Thread> threads;
private int threadAmount;
public Engine(int amountOfThreads)
{
tasks = new BlockingCollection<Task>();
threads = new List<Thread>();
threadAmount = amountOfThreads;
}
public void Start()
{
for (var i = 0; i < threadAmount; i++)
{
var thread = new Thread(Process);
thread.Name = "Thread " + i;
threads.Add(thread);
thread.Start();
}
}
public void Stop()
{
tasks.CompleteAdding();
threads.ForEach(t => t.Join());
}
private void Process()
{
foreach (var task in tasks.GetConsumingEnumerable())
{
task.Execute();
}
}
public void Enqueue(Task t)
{
tasks.Add(t);
}
}
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