张氏万家网站建设,个人主页建站,做网站需要固定ip吗,seo英文一#xff1a;背景 1. 讲故事这个月初#xff0c;有位朋友wx上找到我#xff0c;说他的api过一段时间后#xff0c;就会出现只有请求#xff0c;没有响应的情况#xff0c;截图如下#xff1a;从朋友的描述中看样子程序是被什么东西卡住了#xff0c;这种卡死的问题解决… 一背景 1. 讲故事这个月初有位朋友wx上找到我说他的api过一段时间后就会出现只有请求没有响应的情况截图如下从朋友的描述中看样子程序是被什么东西卡住了这种卡死的问题解决起来相对简单接下来我就用 windbg 给大家分析一下。二Windbg 分析 1. Request 请求正在干嘛既然朋友说 api 有 request 无 response那怎么去验证朋友的话对不对呢我们都知道 .NET 用 HttpContext 来表示一个请求言外之意就是可以去抓 HttpContext 下的时长属性Netext 中有一个 !whttp 命令可以帮助我们。0:000 !whttp
HttpContext Thread Time Out Running Status Verb Url
000000563bf803b0 42 00:01:50 00:01:24 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx-HN
000000563bf84660 -- 00:01:50 Finished 200 GET http://xxx.com:30003/
000000563c4a0470 51 00:01:50 00:00:12 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx2C
00000056bbf63590 30 00:01:50 00:02:41 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx-B2C
00000056bc82a038 -- 00:01:50 Finished 200 GET http://localhost:30003/
00000056bc84a3e8 44 00:01:50 00:00:51 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx
00000056bc8671c8 46 00:01:50 00:00:45 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx-B2C
000000573bf44698 35 00:01:50 00:02:39 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx
000000573bf483c0 33 00:01:50 00:02:41 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx-HN
000000573bf97e80 40 00:01:50 00:02:32 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxZJB2C
000000573c583b08 -- 00:01:50 Finished 200 GET http://localhost:30003/
000000573c589ec8 -- 00:01:50 Finished 200 GET http://xxx.com:30003/Wms/xxx/xxx/xxx
000000573c760e28 -- 00:01:50 Finished 200 POST http://xxx.com:30003/Wms/xxx/xxx/xxx
000000573c95f990 48 00:01:50 00:00:31 200 POST http://xxx.com:30003/Wms/Common/xxx?xxxxxxxxxx-HN
00000057bbf4f8e8 31 00:01:50 00:02:12 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx
00000057bc080340 50 00:01:50 00:00:19 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx
000000583c4aee80 43 00:01:50 00:01:11 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx2B
000000583c4d0c50 53 00:01:50 00:00:01 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx2B
00000058bbf8f1a0 34 00:01:50 00:02:22 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx2B
000000593bfe1758 41 00:01:50 00:01:22 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx2C
000000593c892160 -- 00:01:50 Finished 200 GET http://xxx.com:30003/Wms/xxx/xxx/xxxJob
000000593ca813b0 45 00:01:50 00:00:30 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx-HN
000000593caa45d8 -- 00:01:50 Finished 200 GET http://xxx.com:30003/
00000059bc1ad808 32 00:01:50 00:01:45 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxxxx-B2C
00000059bc1c3d70 36 00:01:50 00:01:29 200 POST http://xxx.com:30003/Wms/xxx/xxx?xxxxxxxxxx25 HttpContext object(s) found matching criteria从 Running 列可以看到大多请求都已经达到1分钟以上这也验证了朋友所说的卡死问题按照经验可以取 Running 列中最大的 httpContext 所在的线程也就是上面的 30 和 33 号线程 看看它们都在干什么2. 探究 Running 最长线程接下来切到 30 和 33 号线程看看它们的线程栈。0:000 ~30s
ntdll!NtWaitForSingleObject0xa:
00007ffdb81f024a c3 ret
0:030 !clrstack
OS Thread Id: 0x29d0 (30)Child SP IP Call Site
0000005acc3ac590 00007ffdb81f024a [PrestubMethodFrame: 0000005acc3ac590] xxx.xxx.RedisConnectionHelp.get_Instance()
0000005acc3ac850 00007ffd4dd78911 xxx.xxx.RedisCache..ctor(Int32, System.String)
0000005acc3ac8c0 00007ffd4dd78038 xxx.xxx.CacheByRedis.HashGet[[System.__Canon, mscorlib]](System.String, System.String, Int32)
0000005acc3ac968 00007ffdabef1f7c [StubHelperFrame: 0000005acc3ac968]
0000005acc3ac9c0 00007ffd4dd77f18 xxx.xxx.Cache.xxx.GetCacheNotAreaDataEntity[[System.__Canon, mscorlib]](System.String, System.String, System.String)...0:030 ~33s
ntdll!NtWaitForMultipleObjects0xa:
00007ffdb81f07ba c3 ret
0:033 !clrstack
OS Thread Id: 0x3ad4 (33)Child SP IP Call Site
0000005accabae90 00007ffdb81f07ba [GCFrame: 0000005accabae90]
0000005accabafb8 00007ffdb81f07ba [HelperMethodFrame_1OBJ: 0000005accabafb8] System.Threading.Monitor.ObjWait(Boolean, Int32, System.Object)
0000005accabb0d0 00007ffdaac60d64 System.Threading.ManualResetEventSlim.Wait(Int32, System.Threading.CancellationToken)
0000005accabb160 00007ffdaac5b4bb System.Threading.Tasks.Task.SpinThenBlockingWait(Int32, System.Threading.CancellationToken)
0000005accabb1d0 00007ffdab5a01d1 System.Threading.Tasks.Task.InternalWait(Int32, System.Threading.CancellationToken)
0000005accabb2a0 00007ffdab59cfa7 System.Threading.Tasks.Task1[[System.__Canon, mscorlib]].GetResultxxx(Boolean)
0000005accabb2e0 00007ffd4d8d338f xxx.Config.xxx.Config1[[System.__Canon, mscorlib]].GetConfig(xxx.Config.Model.ConfigListener, System.Func2xxx.Config.Request.GetConfigRequest,System.Threading.Tasks.Task1System.String)
0000005accabb340 00007ffd4d8d2f40 xxx.Config.xxx.Config1[[System.__Canon, mscorlib]].get_Item(System.String, System.String)
0000005accabb3c0 00007ffd4dd78f7f xxx.Util.BaseConfig.get_GetRedisConn()
0000005accabb440 00007ffd4dd78e9c xxx.xxx.RedisConnectionHelp.GetConnectionString()
0000005accabb4a0 00007ffd4dd789cb xxx.xxx.RedisConnectionHelp..cctor()
0000005accabb940 00007ffdabef6953 [GCFrame: 0000005accabb940]
0000005accabc5b0 00007ffdabef6953 [PrestubMethodFrame: 0000005accabc5b0] xxx.xxx.RedisConnectionHelp.get_Instance()
0000005accabc870 00007ffd4dd78911 xxx.xxx.RedisCache..ctor(Int32, System.String)
0000005accabc8e0 00007ffd4dd78038 xxx.xxx.CacheByRedis.HashGet[[System.__Canon, mscorlib]](System.String, System.String, Int32)
0000005accabc988 00007ffdabef1f7c [StubHelperFrame: 0000005accabc988]
0000005accabc9e0 00007ffd4dd77f18 xxx.Core.Cache.xxx.GetCacheNotAreaDataEntity[[System.__Canon, mscorlib]](System.String, System.String, System.String)
...上面的信息不难发现 30 号线程正卡在 RedisConnectionHelp.get_Instance() 处33 号线已经进入了 RedisConnectionHelp.get_Instance() 方法中最后在 GetConfig() 处等待 Result 的结果按经验来说30 号线程看样子正在锁等待 33 号正在等待异步结果接下来的突破点就是探究下 RedisConnectionHelp.Instance 处代码。3. 寻找问题代码接下来用反编译工具 ILSpy 找到问题代码。public static class RedisConnectionHelp
{public static ConnectionMultiplexer Instance{get{if (_instance null){lock (Locker){if (_instance null || !_instance.IsConnected){_instance GetManager();}}}return _instance;}}
}30 号线程果然是卡在 Locker 处接下来深挖下 33 号线程所执行的 GetManager() 方法简化后代码如下public T this[string dataId, string key ]
{get{try{string config GetConfig(configListener, new NacosConfigClient(Base.NacosConfiguration).DoGetConfigAsync);return JsonConvert.DeserializeObjectT(config);}catch (Exception ex){return default(T);}}
}private string GetConfig(ConfigListener listener, FuncGetConfigRequest, Taskstring action)
{var text2 action(new GetConfigRequest{DataId listener.DataId,Group listener.Group,Tenant text}).Result;return text2;
}internal async Taskstring DoGetConfigAsync(GetConfigRequest request)
{IRestResponse restResponse await HttpUtil.Request(currentServerAddr, Method.GET, request.ParamValues(), xxx);return restResponse.Content;
}可以看到代码卡在了 Result 上无限期等待到这里我就想到了 同步上下文 我看他这个程序是 .NET 4.8 下的 ASP.NET MVC记得不错上下文应该是 AspNetSynchronizationContext具体死锁原因可参见我的这篇文章一句 Task.Result 就死锁, 这代码还怎么写解决办法大概有四种。使用 .ConfigureAwait(false)改成全异步用 Task 再包一层。改成全同步三总结 其实本次事故主要还是因为在 同步代码 中做了 异步代码.Result 导致的死锁问题有非常多的文章都在抨击这种现象在 asp.net core 中已经移除了这种同步上下文的大坑给到朋友的建议是改成全同步死锁问题也随之消失。哈哈真替朋友开心
