好的，所以我遇到了创建一堆线程的问题，而且它们都使用同一个对象。我的想法是，我有一个＆＃34;队列＆＃34;项目（AKA列表）和项目应逐个处理，直到所有项目都已处理完毕。目前这对于一个线程（当我更改threadcount = 1时）工作得很好，但是当我尝试使它成为threadcount = 2并且线程正在竞争时，它们都会变成......一个不好的地方。
这里有一些快速的课程，我们提供了一个详细的例子来说明我想要完成的事情...我有一个非常好的预感，它将与使用＆＃34;锁定＆ ＃34;关键字，但我不能100％确定如何使用它。
在您的回答中，请在解决方案的代码中举例说明您的答案。谢谢！
守则：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.Diagnostics;
namespace MyNamespace
{
class Class1
{
static void Main()
{
Debug.WriteLine("starting application...");
int threadcount = 2;
List<Task> tasks = new List<Task>();
List<Class2> myObjs = new List<Class2>();
myObjs.Add(new Class2("list item 1"));
myObjs.Add(new Class2("list item 2"));
myObjs.Add(new Class2("list item 3"));
myObjs.Add(new Class2("list item 4"));
myObjs.Add(new Class2("list item 5"));
myObjs.Add(new Class2("list item 6"));
myObjs.Add(new Class2("list item 7"));
myObjs.Add(new Class2("list item 8"));
myObjs.Add(new Class2("list item 9"));
Debug.WriteLine("about to create " + threadcount + " task(s)...");
int t = 0;
do
{
t++;
Debug.WriteLine("creating task " + t);
Class3 starter = new Class3();
tasks.Add(starter.StartNewThread(myObjs));
} while (t < threadcount);
Task.WaitAll(tasks.ToArray());
Debug.WriteLine("all tasks have completed");
}
}
class Class2
{
private string m_status;
public string status
{
get { return m_status; }
set { m_status = value; }
}
private string m_text;
public string text
{
get { return m_text; }
set { m_text = value; }
}
private int m_threadid;
public int threadid
{
get { return m_threadid; }
set { m_threadid = value; }
}
public Class2()
{
m_status = "created";
m_text = "";
m_threadid = 0;
}
public Class2(string intext)
{
m_status = "created";
m_text = intext;
m_threadid = 0;
}
}
class Class3
{
public Task StartNewThread(List<Class2> taskObjs)
{
Task<List<Class2>> task = Task.Factory
.StartNew(() => threadTaskWorker(taskObjs),
CancellationToken.None,
TaskCreationOptions.None,
TaskScheduler.Default)
.ContinueWith(completed_task => threadTaskComplete(completed_task.Result));
return task;
}
private List<Class2> threadTaskWorker(List<Class2> taskObjs)
{
Thread.CurrentThread.Name = "thread" + Thread.CurrentThread.ManagedThreadId;
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " created.");
//Process all items in the list that need processing
Class2 nextObj;
do
{
//Look for next item in list that needs processing
nextObj = null;
foreach (Class2 taskObj in taskObjs)
{
if (taskObj.status == "created")
{
nextObj = taskObj;
break;
}
}
if (nextObj != null)
{
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId +
" is handling " + nextObj.text);
nextObj.status = "processing";
nextObj.threadid = Thread.CurrentThread.ManagedThreadId;
nextObj.text += "(handled)";
Random rnd = new Random();
Thread.Sleep(rnd.Next(300, 3000));
nextObj.status = "completed";
}
} while (nextObj != null);
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " destroyed.");
//Return the task object
return taskObjs;
}
private List<Class2> threadTaskComplete(List<Class2> taskObjs)
{
Debug.WriteLine("a thread has finished, here are the current item's status...");
foreach (Class2 taskObj in taskObjs)
{
Debug.WriteLine(taskObj.text +
" thread:" + taskObj.threadid +
" status:" + taskObj.status);
}
//Return the task object
return taskObjs;
}
}
}
结果：
/*
starting application...
about to create 2 task(s)...
creating task 1
creating task 2
thread #10 created.
thread #11 created.
thread #10 is handling list item 1
thread #11 is handling list item 1
thread #10 is handling list item 2
thread #11 is handling list item 2
thread #10 is handling list item 3
thread #11 is handling list item 4
thread #10 is handling list item 5
thread #11 is handling list item 5
thread #10 is handling list item 6
thread #11 is handling list item 6
thread #10 is handling list item 7
thread #11 is handling list item 8
thread #10 is handling list item 9
thread #11 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 2(handled)(handled) thread:11 status:completed
list item 3(handled) thread:10 status:completed
list item 4(handled) thread:11 status:completed
list item 5(handled)(handled) thread:11 status:completed
list item 6(handled)(handled) thread:11 status:completed
list item 7(handled) thread:10 status:completed
list item 8(handled) thread:11 status:completed
list item 9(handled) thread:10 status:processing
thread #10 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 2(handled)(handled) thread:11 status:completed
list item 3(handled) thread:10 status:completed
list item 4(handled) thread:11 status:completed
list item 5(handled)(handled) thread:11 status:completed
list item 6(handled)(handled) thread:11 status:completed
list item 7(handled) thread:10 status:completed
list item 8(handled) thread:11 status:completed
list item 9(handled) thread:10 status:completed
all tasks have completed
*/
预期结果：
/*
starting application...
about to create 2 task(s)...
creating task 1
creating task 2
thread #10 created.
thread #11 created.
thread #10 is handling list item 1
thread #11 is handling list item 2
thread #10 is handling list item 3
thread #11 is handling list item 4
thread #10 is handling list item 5
thread #10 is handling list item 6
thread #11 is handling list item 7
thread #10 is handling list item 8
thread #11 is handling list item 9
thread #10 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:10 status:completed
list item 2(handled) thread:11 status:completed
list item 3(handled) thread:10 status:completed
list item 4(handled) thread:11 status:completed
list item 5(handled) thread:10 status:completed
list item 6(handled) thread:10 status:completed
list item 7(handled) thread:11 status:completed
list item 8(handled) thread:10 status:completed
list item 9(handled) thread:11 status:processing
thread #11 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:10 status:completed
list item 2(handled) thread:11 status:completed
list item 3(handled) thread:10 status:completed
list item 4(handled) thread:11 status:completed
list item 5(handled) thread:10 status:completed
list item 6(handled) thread:10 status:completed
list item 7(handled) thread:11 status:completed
list item 8(handled) thread:10 status:completed
list item 9(handled) thread:11 status:completed
all tasks have completed
*/
答案 0 :(得分：2)
如果您不想使用ConcurrentQueue或者您正在使用非线程安全的其他共享资源，请使用您之前在使用lock关键字时指出的选项。
来自MSDN：
lock关键字通过获取给定对象的互斥锁，执行语句，然后释放锁来将语句块标记为关键部分。
当线程获得给定object的锁定时，遇到lock(object)语句的其他线程必须等待锁定变为可用才能继续。
/// any resource shared between threads
private List<int> sharedResource = new List<int>();
/// best practice is to use a private object to synchronise threads
/// see: https://msdn.microsoft.com/en-us/library/c5kehkcz.aspx
private object resourceLock = new object();
void MethodAccessingSharedResource()
{
/// Only one thread can acquire the lock on resourceLock at a time.
lock (resourceLock)
{
/// The thread can safely access the shared resource here.
/// Other threads will wait at lock(resourceLock) until
/// this thread gives up the lock.
}
/// The thread has released the lock on resourceLock.
/// Another thread can now enter the lock(){} code block.
}
答案 1 :(得分：1)
首先，感谢@khargoosh和@interceptwind的投入！帮助我了解锁并提出这个解决方案是关键。这就是我提出的最终工作结果！它已经过测试，结果是实际结果。在答案中，我决定使用4个线程来显示结果。
守则：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.Diagnostics;
namespace MyNamespace
{
class Class1
{
static void Main()
{
Debug.WriteLine("starting application...");
int threadcount = 4;
List<Task> tasks = new List<Task>();
List<Class2> myObjs = new List<Class2>();
myObjs.Add(new Class2("list item 1"));
myObjs.Add(new Class2("list item 2"));
myObjs.Add(new Class2("list item 3"));
myObjs.Add(new Class2("list item 4"));
myObjs.Add(new Class2("list item 5"));
myObjs.Add(new Class2("list item 6"));
myObjs.Add(new Class2("list item 7"));
myObjs.Add(new Class2("list item 8"));
myObjs.Add(new Class2("list item 9"));
Debug.WriteLine("about to create " + threadcount + " task(s)...");
int t = 0;
do
{
t++;
Debug.WriteLine("creating task " + t);
Class3 starter = new Class3();
tasks.Add(starter.StartNewThread(myObjs));
} while (t < threadcount);
Task.WaitAll(tasks.ToArray());
Debug.WriteLine("all tasks have completed");
}
}
class Class2
{
private object m_locker = new object();
public object locker
{
get { return m_locker; }
set { m_locker = value; }
}
private string m_status;
public string status
{
get { return m_status; }
set { m_status = value; }
}
private string m_text;
public string text
{
get { return m_text; }
set { m_text = value; }
}
private int m_threadid;
public int threadid
{
get { return m_threadid; }
set { m_threadid = value; }
}
public Class2()
{
m_status = "created";
m_text = "";
m_threadid = 0;
}
public Class2(string intext)
{
m_status = "created";
m_text = intext;
m_threadid = 0;
}
}
class Class3
{
public Task StartNewThread(List<Class2> taskObjs)
{
Task<List<Class2>> task = Task.Factory
.StartNew(() => threadTaskWorker(taskObjs),
CancellationToken.None,
TaskCreationOptions.None,
TaskScheduler.Default)
.ContinueWith(completed_task => threadTaskComplete(completed_task.Result));
return task;
}
private List<Class2> threadTaskWorker(List<Class2> taskObjs)
{
Thread.CurrentThread.Name = "thread" + Thread.CurrentThread.ManagedThreadId;
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " created.");
//Process all items in the list that need processing
Class2 nextObj;
do
{
//Look for next item in list that needs processing
nextObj = null;
foreach (Class2 taskObj in taskObjs)
{
nextObj = taskObj;
lock (nextObj.locker)
{
if (taskObj.status == "created")
{
nextObj.status = "processing";
break;
}
else nextObj = null;
}
}
if (nextObj != null)
{
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId +
" is handling " + nextObj.text);
nextObj.threadid = Thread.CurrentThread.ManagedThreadId;
nextObj.text += "(handled)";
Random rnd = new Random();
Thread.Sleep(rnd.Next(300, 3000));
nextObj.status = "completed";
}
} while (nextObj != null);
Debug.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " destroyed.");
//Return the task object
return taskObjs;
}
private List<Class2> threadTaskComplete(List<Class2> taskObjs)
{
Debug.WriteLine("a thread has finished, here are the current item's status...");
foreach (Class2 taskObj in taskObjs)
{
Debug.WriteLine(taskObj.text +
" thread:" + taskObj.threadid +
" status:" + taskObj.status);
}
//Return the task object
return taskObjs;
}
}
}
结果：
/*
starting application...
about to create 4 task(s)...
creating task 1
creating task 2
creating task 3
creating task 4
thread #11 created.
thread #13 created.
thread #12 created.
thread #12 is handling list item 3
thread #11 is handling list item 1
thread #13 is handling list item 2
thread #14 created.
thread #14 is handling list item 4
thread #12 is handling list item 5
thread #11 is handling list item 6
thread #13 is handling list item 7
thread #14 is handling list item 8
thread #12 is handling list item 9
thread #11 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 2(handled) thread:13 status:completed
list item 3(handled) thread:12 status:completed
list item 4(handled) thread:14 status:completed
list item 5(handled) thread:12 status:completed
list item 6(handled) thread:11 status:completed
list item 7(handled) thread:13 status:processing
list item 8(handled) thread:14 status:processing
list item 9(handled) thread:12 status:processing
thread #13 destroyed.
thread #14 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 2(handled) thread:13 status:completed
list item 3(handled) thread:12 status:completed
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 4(handled) thread:14 status:completed
list item 5(handled) thread:12 status:completed
list item 2(handled) thread:13 status:completed
list item 3(handled) thread:12 status:completed
list item 6(handled) thread:11 status:completed
list item 7(handled) thread:13 status:completed
list item 4(handled) thread:14 status:completed
list item 5(handled) thread:12 status:completed
list item 8(handled) thread:14 status:completed
list item 9(handled) thread:12 status:processing
list item 6(handled) thread:11 status:completed
list item 7(handled) thread:13 status:completed
list item 8(handled) thread:14 status:completed
list item 9(handled) thread:12 status:processing
thread #12 destroyed.
a thread has finished, here are the current item's status...
list item 1(handled) thread:11 status:completed
list item 2(handled) thread:13 status:completed
list item 3(handled) thread:12 status:completed
list item 4(handled) thread:14 status:completed
list item 5(handled) thread:12 status:completed
list item 6(handled) thread:11 status:completed
list item 7(handled) thread:13 status:completed
list item 8(handled) thread:14 status:completed
list item 9(handled) thread:12 status:completed
all tasks have completed
*/
答案 2 :(得分：0)
如果您确实需要可以同时访问的项目的先进先出队列，请使用ConcurrentQueue。使用TryDequeue（）方法检索对象将确保每个对象只被访问一次。
示例：
var cq = new ConcurrentQueue<T>();
//populate queue
...
//process queue until empty -- this can be done in parallel
T item;
while(cq.trydequeue(out item)){
//process item
}
//queue was empty when we tried to retrieve something.
答案 3 :(得分：0)
首先，您需要在Class2
中使用另一个对象作为储物柜class Class2
{
public object locker = new object();
private string m_status;
...
}
编辑：接下来，在Class3的处理循环中，您需要先检查您的nextObj.status是否已“创建”。如果是，请将其更改为“处理”并继续处理。如果没有跳到下一个对象。
请注意，我们将锁定nextObj.status以防止2个线程同时访问它。 （基于MoreOn的评论）
private List<Class2> threadTaskWorker(List<Class2> taskObjs)
{
Thread.CurrentThread.Name = "thread" + Thread.CurrentThread.ManagedThreadId;
Console.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " created.");
//Process all items in the list that need processing
foreach (Class2 nextObj in taskObjs)
{
Console.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId +
" is handling " + nextObj.text);
lock (nextObj.locker)
{
if (nextObj.status == "created")
nextObj.status = "processing";
else
continue;
}
nextObj.status = "processing";
nextObj.threadid = Thread.CurrentThread.ManagedThreadId;
nextObj.text += "(handled)";
Random rnd = new Random();
Thread.Sleep(rnd.Next(300, 3000));
nextObj.status = "completed";
}
Console.WriteLine("thread #" + Thread.CurrentThread.ManagedThreadId + " destroyed.");
return taskObjs;
}