CPU 100% 問(wèn)題分析，我們把博客園踩過(guò)的坑又踩了一遍《二》(補(bǔ)充)

cpu 和內(nèi)存不高，但是線上系統(tǒng)運(yùn)行很卡 cpu使用率瞬時(shí)升高，甚至突破100%（負(fù)載突然升高）其它服務(wù)(或者進(jìn)程外的資源)傳入負(fù)載能力超出（或提示連接超時(shí)）,比如提示（StackExchange.Redis.RedisConnectionException: It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. Timeout at StackExchange.Redis.ConnectionMultiplexer.ConnectImpl(Func`1 multiplexerFactory, TextWriter log)）也可能是一次顯示為"較長(zhǎng)"的數(shù)據(jù)庫(kù)查詢或者任何非cpu活動(dòng)（如任何I/O或延遲），因此似乎非常I/O 操作隨機(jī)需要的時(shí)間比它應(yīng)該需要的時(shí)間長(zhǎng) 線程數(shù)莫名奇妙的不斷升高

問(wèn)題如下：

針對(duì).net core 異常奇怪問(wèn)題分析

1、StackExchange.Redis.RedisConnectionException: It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. Timeout
at StackExchange.Redis.ConnectionMultiplexer.ConnectImpl(Func`1 multiplexerFactory, TextWriter log)

2、There is already an open DataReader associated with this Command which must be closed first

3、A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext, however instance members are not guaranteed to be

static void Main(string[] args)
        {
          //按鍵后開始執(zhí)行
            Console.ReadKey();
            //模擬并發(fā)
            while (true)
            {
                Task.Run(Producer);
                Thread.Sleep(200);
            }
           
        }
        /// <summary>
        /// 如果處理程序耗時(shí)>請(qǐng)求耗時(shí)，也就是說(shuō)引起并發(fā)，就會(huì)導(dǎo)致死鎖
        /// </summary>
        static void Producer()
        {
            var result = Process().Result;
            //或者
            //Process().Wait();
        }


        static async Task<bool> Process()
        {
            Console.WriteLine("Start - " + DateTime.Now.ToLongTimeString());
            await Task.Run(() =>
            {
                //模擬任務(wù)執(zhí)行耗時(shí)
                Thread.Sleep(1000);
            });

            Console.WriteLine("Ended - " + DateTime.Now.ToLongTimeString());
            return true;
        }

執(zhí)行效果：

以上可看出：

1、控制臺(tái)執(zhí)行5-10個(gè)任務(wù)后，不再執(zhí)行Ended 語(yǔ)句的任何內(nèi)容(Ended語(yǔ)句全部被阻塞）

2、內(nèi)存占用穩(wěn)步上升

3、AsyncTest.exe 線程每秒增加一個(gè)

解決方案：

var result = Process().ConfigureAwait(false);

或修改為異步方法（強(qiáng)烈推薦）

 　　　　static async Task Producer()
        {
            await Process();
        }

---補(bǔ)充 2021.2.26-------------------

優(yōu)化代碼后進(jìn)一步測(cè)試

測(cè)試代碼如下：

  1 using System;
  2 using System.Threading;
  3 using System.Threading.Tasks;
  4 
  5 namespace AsyncTest
  6 {
  7     class Program
  8     {
  9         static void Main(string[] args)
 10         {
 11             Console.ReadKey();
 12             //模擬并發(fā)
 13             for (int i = 0; i < 300; i++)
 14             {
 15                
 16                 Task.Run(() => 
 17                      Producer(i)
 18                 );
 19                 // Task.Run(Producer3);
 20                 // Task.Run(ProducerQueue);
 21                 Thread.Sleep(300);
 22             }
 23         }
 24         /// <summary>
 25         /// 如果處理程序耗時(shí)>請(qǐng)求耗時(shí)，也就是說(shuō)引起并發(fā)，就會(huì)導(dǎo)致死鎖
 26         /// </summary>
 27         static void Producer(int i)
 28         {
 29             var result = Process(i).Result;
 30             //或者
 31             //Process().Wait();
 32         }
 33         /// <summary>
 34         /// 正常
 35         /// </summary>
 36         static void Producer2(int i)
 37         {
 38             var result = Process(i).ConfigureAwait(false);
 39         }
 40         //cpu 內(nèi)存均正常
 41         static async Task Producer3(int i)
 42         {
 43             await Process(i);
 44         }
 45 
 46         /// <summary>
 47         /// 
 48         /// </summary>
 49         static void ProducerQueue(int i)
 50         {
 51             ProcessQueue(i).Wait();
 52             //或者
 53             //Process().Wait();
 54         }
 55         /// <summary>
 56         /// 正常
 57         /// </summary>
 58         static void ProducerQueue2(int i)
 59         {
 60             var result = ProcessQueue(i).ConfigureAwait(false);
 61         }
 62         //cpu 內(nèi)存均正常
 63         static async Task ProducerQueue3(int i)
 64         {
 65             await ProcessQueue(i);
 66         }
 67 
 68         static async Task<bool> Process(int i)
 69         {
 70             ConsoleWrite($"Start{i}");
 71             await Task.Run(() =>
 72             {
 73                 //模擬任務(wù)執(zhí)行耗時(shí)
 74                 Thread.Sleep(2000);
 75             });
 76 
 77             ConsoleWrite($"End{i}");
 78             return true;
 79         }
 80 
 81 
 82 
 83         static async Task ProcessQueue(int i)
 84         {
 85             ConsoleWrite($"Start{i}");
 86             ThreadPool.QueueUserWorkItem(state =>
 87             {
 88                 ConsoleWrite("Hello" + (string)state);
 89             }, await GetName(i));
 90             ConsoleWrite($"End{i}");
 91         }
 92 
 93         private static async Task<string> GetName(int i)
 94         {
 95             Thread.Sleep(1000);
 96             Random r = new Random();
 97             return $"ZhiXin[{r.Next(100, 999)}]-[{i}]";
 98         }
 99         private static string GetCurrentThreadID()
100         {
101             return $" {DateTime.Now.ToLongTimeString()} --ThreadId[{Thread.CurrentThread.ManagedThreadId.ToString("0000")}]";
102         }
103         private static void ConsoleWrite(string type)
104         {
105             if (type.Contains("Start"))
106             {
107                 //Console.BackgroundColor = ConsoleColor.Blue; //設(shè)置背景色
108                 Console.ForegroundColor = ConsoleColor.Green; //設(shè)置前景色，即字體顏色
109             }
110             else if (type.Contains("End"))
111             {
112                 // Console.BackgroundColor = ConsoleColor.Red; //設(shè)置背景色
113                 Console.ForegroundColor = ConsoleColor.Red; //設(shè)置前景色，即字體顏色
114             }
115             Console.WriteLine($"{type} - " + GetCurrentThreadID());
116         }
117     }
118 }

使用.Result異步調(diào)用

結(jié)果如下：

測(cè)試代碼如下：

  1 using System;
  2 using System.Threading;
  3 using System.Threading.Tasks;
  4 
  5 namespace AsyncTest
  6 {
  7     class Program
  8     {
  9         static void Main(string[] args)
 10         {
 11             Console.ReadKey();
 12             //模擬并發(fā)
 13             for (int i = 0; i < 300; i++)
 14             {
 15                
 16                 Task.Run(() => 
 17                      Producer3(i)
 18                 );
 19                 // Task.Run(Producer3);
 20                 // Task.Run(ProducerQueue);
 21                 Thread.Sleep(300);
 22             }
 23         }
 24         /// <summary>
 25         /// 如果處理程序耗時(shí)>請(qǐng)求耗時(shí)，也就是說(shuō)引起并發(fā)，就會(huì)導(dǎo)致死鎖
 26         /// </summary>
 27         static void Producer(int i)
 28         {
 29             var result = Process(i).Result;
 30             //或者
 31             //Process().Wait();
 32         }
 33         /// <summary>
 34         /// 正常
 35         /// </summary>
 36         static void Producer2(int i)
 37         {
 38             var result = Process(i).ConfigureAwait(false);
 39         }
 40         //cpu 內(nèi)存均正常
 41         static async Task Producer3(int i)
 42         {
 43             await Process(i);
 44         }
 45 
 46         /// <summary>
 47         /// 
 48         /// </summary>
 49         static void ProducerQueue(int i)
 50         {
 51             ProcessQueue(i).Wait();
 52             //或者
 53             //Process().Wait();
 54         }
 55         /// <summary>
 56         /// 正常
 57         /// </summary>
 58         static void ProducerQueue2(int i)
 59         {
 60             var result = ProcessQueue(i).ConfigureAwait(false);
 61         }
 62         //cpu 內(nèi)存均正常
 63         static async Task ProducerQueue3(int i)
 64         {
 65             await ProcessQueue(i);
 66         }
 67 
 68         static async Task<bool> Process(int i)
 69         {
 70             ConsoleWrite($"Start{i}");
 71             await Task.Run(() =>
 72             {
 73                 //模擬任務(wù)執(zhí)行耗時(shí)
 74                 Thread.Sleep(2000);
 75             });
 76 
 77             ConsoleWrite($"End{i}");
 78             return true;
 79         }
 80 
 81 
 82 
 83         static async Task ProcessQueue(int i)
 84         {
 85             ConsoleWrite($"Start{i}");
 86             ThreadPool.QueueUserWorkItem(state =>
 87             {
 88                 ConsoleWrite("Hello" + (string)state);
 89             }, await GetName(i));
 90             ConsoleWrite($"End{i}");
 91         }
 92 
 93         private static async Task<string> GetName(int i)
 94         {
 95             Thread.Sleep(1000);
 96             Random r = new Random();
 97             return $"ZhiXin[{r.Next(100, 999)}]-[{i}]";
 98         }
 99         private static string GetCurrentThreadID()
100         {
101             return $" {DateTime.Now.ToLongTimeString()} --ThreadId[{Thread.CurrentThread.ManagedThreadId.ToString("0000")}]";
102         }
103         private static void ConsoleWrite(string type)
104         {
105             if (type.Contains("Start"))
106             {
107                 //Console.BackgroundColor = ConsoleColor.Blue; //設(shè)置背景色
108                 Console.ForegroundColor = ConsoleColor.Green; //設(shè)置前景色，即字體顏色
109             }
110             else if (type.Contains("End"))
111             {
112                 // Console.BackgroundColor = ConsoleColor.Red; //設(shè)置背景色
113                 Console.ForegroundColor = ConsoleColor.Red; //設(shè)置前景色，即字體顏色
114             }
115             Console.WriteLine($"{type} - " + GetCurrentThreadID());
116         }
117     }
118 }

使用await關(guān)鍵字異步調(diào)用

結(jié)果如下：

ps:截屏工具 ScreenToGif

參考：

又踩.NET Core的坑：在同步方法中調(diào)用異步方法Wait時(shí)發(fā)生死鎖(deadlock)

一碼阻塞，萬(wàn)碼等待：ASP.NET Core 同步方法調(diào)用異步方法“死鎖”的真相

.NET Core中遇到奇怪的線程死鎖問(wèn)題：內(nèi)存與線程數(shù)不停地增長(zhǎng)

C#同步方法中如何調(diào)用異步方法？值得一看

理解C#中的ConfigureAwait

bindot:http://www.rzrgm.cn/bindot/p/cpu100.html

posted @ 2021-02-02 16:22 FengLu-1 閱讀(1264) 評(píng)論(4) 收藏舉報(bào)

刷新頁(yè)面返回頂部

bindot

CPU 100% 問(wèn)題分析，我們把博客園踩過(guò)的坑又踩了一遍《二》(補(bǔ)充)

公告