.NET 某云采购平台API 挂死问题解析_开发_开发者

一：背景

1. 讲故事

大概有两个月没写博客了，关注我的朋友应该知道我最近都把精力花在了星球，这两个月时间也陆陆续续的有朋友求助如何分析dump，有些朋友太客气了，给了大大的红包，哈哈，手里面也攒了10多个不同问题类型的dump，后续也会逐一将分析思路贡献出来。

这个dump是一位朋友大概一个月php前提供给我的，由于wx里面求助的朋友比较多，一时也没找到相关截图，不得已破坏一下老规矩。

既然朋友说api接口无响应，呈现了hangon现编程象，从一些过往经验看，大概也只有三种情况。

大量锁等待
线程不够用
死锁

有了这种先入为主的思想，那就上windbg说事呗。

二： windbg 分析

1. 有大量锁等待吗？

要想看是否锁等待，老规矩，看一下 同步块表。

0:000> !syncblk
Index Syncblock MonitorHeld Recursion Owning Thread Info  SyncBlock Owner
-----------------------------
Total           1673
CCW             3
RCW             4
ComClassFactory 0
Free            397

扑了个空，啥也没有，那就暴力看看所有的线程栈吧。

.NET 某云采购平台API 挂死问题解析

不看还好，一看吓一跳，有339个线程卡在了 System.Threading.Monitor.ObjWait(Boolean, Int32, System.Object) 处，不过转念一想，就算有339个线程卡在这里，真的会导致程序hangon吗？也不一定，毕竟我看过有1000+的线程也不会卡死，只不过cpu爆高而已，接下来继续研判一下是不是线程不够用导致，可以从 线程池任务队列 上面入手。

2. 探究线程池队列

可以用 !tp 命令查看。

0:000> !tp
CPU utilization: 10%
Worker Thread: Total: 328 Running: 328 Idle: 0 MaxLimit: 32767 MinLimit: 4
Work Request in Queue: 74
    Unknown Function: 00007ffe91cc17d0  Context: 000001938b5d8d98
    Unknown Function: 00007ffe91cc17d0  Context: 000001938b540238
    Unknown Function: 00007ffe91cc17d0  Context: 000001938b5eec08
    ...
    Unknown Function: 00007ffe91cc17d0  Context: 0000019390552948
    Unknown Function: 00007ffe91cc17d0  Context: 0000019390562398
    Unknown Function: 00007ffe91cc17d0  Context: 0000019390555b30
--------------------------------------
Number of Timers: 0
----------------------------编程客栈----------
Completion Port Thread:Total: 5 Free: 4 MaxFree: 8 CurrentLimit: 4 MaxLimit: 1000 MinLimit: 4

从输出信息看，线程池中328个线程全部打满，工作队列中还有74位客人在等待，综合这两点信息就已经很清楚了，本次hangon是由于大量的客人到来超出了线程池的接待能力所致。

3. 接待能力真的不行吗？

这个标题我觉得很好，真的不行吗？到底行不行，可以从两点入手：

是不是代码写的烂?
qps是不是真的超出了接待能力？

要想找出答案，还得从那 339 个卡死的线程说起，仔细研究了下每一个线程的调用栈，大概卡死在这三个地方。

<1>. GetModel

public static T GetModel<T, K>(string url, K content)
{
	T result = default(T);
	HttpClientHandler httpClientHandler = new HttpClientH编程andler();
	httpClientHandler.AutomaticDecompression = DecompressionMethods.GZip;
	HttpClientHandler handler = httpClientHandler;
	using (HttpClient httpClient = new HttpClient(handler))
	{
		string content2 = jsonConvert.SerializeObject((object)content);
		HttpContent httpContent = new StringContent(content2);
		httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
		string mD5ByCrypt = Md5.GetMD5ByCrypt(ConfigurationManager.AppSettings["SsoToken"] + DateTime.Now.ToString("yyyyMMdd"));
		httpClient.DefaultRequestHeaders.Add("token", mD5ByCrypt);
		httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
		HttpResponseMessage result2 = httpClient.PostAsync(url, httpContent).Result;
		if (result2.IsSuccessStatusCode)
		{
			string result3 = result2.Content.ReadAsStringAsync().Result;
			return JsonConvert.DeserializeObject<T>(result3);
		}
		return result;
	}
}

<2>. Get

public static T Get<T>(string url, string serviceModuleName)
{
	try
	{
		T val3 = default(T);
		HttpClient httpClient = TryGetClient(serviceModuleName, true);
		using (HttpResponseMessage httpResponseMessage = httpClient.GetAsync(GetRelativeRquestUrl(url, serviceModuleName, true)).Result)
		{
			if (httpResponseMessage.IsSuccessStatusCode)
			{
				string result = httpResponseMessage.Content.ReadAsStringAsync().Result;
				if (!string.IsNullOrEmpty(result))
				{
					val3 = JsonConvert.DeserializeObject<T>(result);
				}
			}
		}
		T val4 = val3;
		val5 = val4;
		return val5;
	}
	catch (Exception exceptiwww.devze.comon)
	{
		throw;
	}
}

<3>. GetStreamByApi

public static Stream GetStreamByApi<T>(string url, T content)
{
	Stream result = null;
	HttpClientHandler httpClientHandler = new HttpClientHandler();
	httpClientHandler.AutomaticDecompression = DecompressionMethods.GZip;
	HttpClientHandler handler = httpClientHandler;
	using (HttpClient httpClient = new HttpClient(handler))
	{
		httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/octet-stream"));
		string content2 = JsonConvert.SerializeObject((object)content);
		HttpContent httpContent = new StringContent(content2);
		httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
		HttpResponseMessage result2 = httpClient.PostAsync(url, httpContent).Result;
		if (result2.IsSuccessStatusCode)
		{
			result = result2.Content.ReadAsStreamAsync().Result;
		}
		httpContent.Dispose();
		return result;
	}
}