[游戏开发]unity与多线程，子线程的崩溃会卡死主线程

http://blog.sina.com.cn/s/blog_471132920101hh5d.html
https://www.jianshu.com/p/95784290a384
https://www.cnblogs.com/HangZhe/p/7273227.html
https://kb.cnblogs.com/page/88513/
https://www.cnblogs.com/OceanEyes/p/coroutine_vs_threading.html
https://github.com/rhedgeco/unity_multithreading_handler 代码

举例1：使用多线程

using System.Collections;
using System.Collections.Generic;
using System.Threading;
using UnityEngine;

public class UseThread : MonoBehaviour
{
    private int count = 0;
    void Start()
    {
        Thread t1 = new Thread(SayHello);
        Thread t2 = new Thread(SayNihao);
        t1.Name = "t1";
        t2.Name = "t2";
        t1.Start("xiaoming");
        t2.Start(123);
    }

    private void SayHello(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            Debug.LogError("hello " + param.ToString() + "  " + Thread.CurrentThread.Name + "  " + Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(1000);
        }
    }

    private void SayNihao(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            Debug.LogError("你好 " + param.ToString() + "  " + Thread.CurrentThread.Name + "  " + Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(1000);
        }
    }

    void Update()
    {
        count++;
        if (count % 1000 == 0)
        {
            Debug.LogError("mainThread " + Thread.CurrentThread.Name + "  " + Thread.CurrentThread.ManagedThreadId);
            count = 0;
        }
    }
}

上面在start方法中，创建了两个子线程。
线程1：执行SayHello方法
线程2：执行SayNihao方法
主线程：执行Update方法

举例2：两个子线程同时访问queue

using System.Collections;
using System.Collections.Generic;
using System.Threading;
using UnityEngine;

public class UseQueueInMultiThread : MonoBehaviour
{
    private int count = 0;
    private Queue<string> m_queue = new Queue<string>();
    private static readonly object m_lock = new object();
    void Start()
    {
        Thread t1 = new Thread(SayHello);
        Thread t2 = new Thread(SayNihao);
        t1.Name = "t1";
        t2.Name = "t2";
        t1.Start("xiaoming");
        t2.Start(123);
    }

    private void SayHello(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            lock(m_lock) //如果未加锁，则导致最后输出的m_queue.count不等于总共的600
            {
                m_queue.Enqueue(i + "   " + param.ToString());
            }
            Thread.Sleep(10);
        }
    }

    private void SayNihao(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            lock (m_lock) //如果未加锁，则导致最后输出的m_queue.count不等于总共的600
            {
                m_queue.Enqueue(i + "   " + param.ToString());
            }
            Thread.Sleep(10);
        }
    }

    void Update()
    {
        count++;
        if (count % 200 == 0)
        {
            Debug.LogError("queue count=" + m_queue.Count);
            count = 0;
        }
    }
}

上面如果将lock(m_lock)去除掉，则会看到在update中最后的输出，有可能不等于600。

举例3：主线程的卡死问题
这个问题，还是很难，或者很容易解决的。
lock的最后编译成的是：

Monitor.Enter
	……
Monitor.Exit

但是如果在Enter和Exit直接报错或者出现exception的话，会直接卡死主线程。示例代码：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using UnityEngine;

public class UseQueueInMultiThread : MonoBehaviour
{
    private int count = 0;
    private Queue<string> m_queue = new Queue<string>();
    private static readonly object m_lock = new object();
    private Thread t1;
    private Thread t2;
    private List<int> m_list = new List<int>();
    void Start()
    {
        t1 = new Thread(SayHello);
        t2 = new Thread(SayNihao);
        t1.Name = "t1";
        t2.Name = "t2";
        t1.Start("xiaoming");
        //t2.Start(123);
    }

    private void SayHello(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            //lock (m_lock) //如果未加锁，则导致最后输出的m_queue.count不等于总共的600
            //try
            {
                Monitor.Enter(m_lock);
                m_queue.Enqueue(i + "   " + param.ToString());
                Debug.LogError("SayHello " + i);
                if (i == 100)
                {
                    //throw new System.Exception("xxxxxxxxxxx");
                    Debug.LogError("dd = " + m_list[1]); //数组越界会卡死主线程
                }
                Debug.LogError("yyyyyyyyyyyy");
            }
            //catch (Exception ex)
            //{
            //    Debug.LogError("ddaaaaaaaa " + ex.ToString());
            //}
            Monitor.Exit(m_lock);
            Thread.Sleep(10);
        }
    }

    private void SayNihao(object param)
    {
        for (int i = 0; i < 300; ++i)
        {
            //lock (m_lock) //如果未加锁，则导致最后输出的m_queue.count不等于总共的600
            Monitor.Enter(m_lock);
            {
                m_queue.Enqueue(i + "   " + param.ToString());
                Debug.LogError("SayNihao " + i);
            }
            Monitor.Exit(m_lock);
            Thread.Sleep(10);
        }
    }

    void Update()
    {
        count++;
        if (count % 10 == 0)
        {
            Debug.LogError("queue count=" + m_queue.Count + "  " + t1.ThreadState + "  " + t2.ThreadState);
            count = 0;
        }

        Monitor.Enter(m_lock);
        Debug.LogError("xxxxxxxxxxaaaaaaaaaaaa");
        Monitor.Exit(m_lock);
    }
}