做网站编辑如何写好一篇新闻,室内装修设计软件推荐,网络营销渠道策略包括,html5网页代码大全一#xff1a;背景 1. 讲故事这个月中旬#xff0c;有位朋友加我wx求助他的程序线程占有率很高#xff0c;寻求如何解决#xff0c;截图如下#xff1a;说实话#xff0c;和不同行业的程序员聊天还是蛮有意思的#xff0c;广交朋友#xff0c;也能扩大自己的圈子#… 一背景 1. 讲故事这个月中旬有位朋友加我wx求助他的程序线程占有率很高寻求如何解决截图如下说实话和不同行业的程序员聊天还是蛮有意思的广交朋友也能扩大自己的圈子朋友说他因为这个bug还导致项目黄了一个... 哈哈看样子是客户不买账验收不了害。。。早找到我这客户不就捞回来啦这也许就是技术的价值吧既然找到我那就让这个挂死问题彻底消失吧上windbg说话。二Windbg 分析 1. 查看线程情况既然朋友说线程高那就从线程入手用 !t 命令即可。0:000 !t
ThreadCount: 1006
UnstartedThread: 0
BackgroundThread: 1005
PendingThread: 0
DeadThread: 0
Hosted Runtime: noLock DBG ID OSID ThreadOBJ State GC Mode GC Alloc Context Domain Count Apt Exception0 1 10c8 00000000004D89A0 2a020 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 MTA 2 2 13c0 000000000031FF70 2b220 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 MTA (Finalizer) 3 3 12cc 000000000032B780 102a220 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 MTA (Threadpool Worker) 4 5 138c 000000000039E3C0 8029220 Preemptive 00000000B6D3CCA0:00000000B6D3D260 00000000002f1070 0 MTA (Threadpool Completion Port) 6 6 106c 0000000019E562A0 3029220 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 MTA (Threadpool Worker) 8 11 7f0 0000000019F8F9E0 20220 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 Ukn 9 1949 323c 000000009AA69E40 8029220 Preemptive 00000000B6BB8AD0:00000000B6BB94E0 00000000002f1070 0 MTA (Threadpool Completion Port) 10 1637 b3c 000000009AA1C260 8029220 Preemptive 00000000B6CD4220:00000000B6CD47E0 00000000002f1070 0 MTA (Threadpool Completion Port) 11 1947 223c 000000009ADB72E0 8029220 Preemptive 00000000B6D88D68:00000000B6D89550 00000000002f1070 0 MTA (Threadpool Completion Port) 12 1968 2e74 000000009AA1E330 8029220 Preemptive 00000000B6A8CD40:00000000B6A8D300 00000000002f1070 0 MTA (Threadpool Completion Port)
...994 313 1fa4 000000009A81FFC0 8029220 Preemptive 00000000B6BFC1B8:00000000B6BFC410 00000000002f1070 0 MTA (Threadpool Completion Port) 995 1564 18ec 000000009A835510 8029220 Preemptive 00000000B6AC1ED0:00000000B6AC2490 00000000002f1070 0 MTA (Threadpool Completion Port) 996 1581 4ac 000000001C2E36E0 8029220 Preemptive 00000000B6C51500:00000000B6C51AC0 00000000002f1070 0 MTA (Threadpool Completion Port) 997 814 2acc 000000009A73B5E0 8029220 Preemptive 00000000B6D67BF8:00000000B6D683E0 00000000002f1070 0 MTA (Threadpool Completion Port) 998 517 25dc 000000009A838990 8029220 Preemptive 00000000B6D2CA10:00000000B6D2CFD0 00000000002f1070 0 MTA (Threadpool Completion Port) 999 670 2a10 000000001C2E4400 8029220 Preemptive 00000000B6CD0490:00000000B6CD0A50 00000000002f1070 0 MTA (Threadpool Completion Port)
1000 183 1704 000000009A81F930 8029220 Preemptive 00000000B6AE8670:00000000B6AE8C30 00000000002f1070 0 MTA (Threadpool Completion Port)
1001 117 1bcc 000000009A73BC70 8029220 Preemptive 00000000B6B92780:00000000B6B92D40 00000000002f1070 0 MTA (Threadpool Completion Port)
1002 1855 1d68 000000009A81E580 8029220 Preemptive 00000000B6B28460:00000000B6B28A20 00000000002f1070 0 MTA (Threadpool Completion Port)
1003 1070 2ef0 000000009A73C300 8029220 Preemptive 00000000B6B8F640:00000000B6B8FC00 00000000002f1070 0 MTA (Threadpool Completion Port)
1004 1429 210c 000000001C2E4A90 8029220 Preemptive 00000000B6D5F488:00000000B6D5FC70 00000000002f1070 0 MTA (Threadpool Completion Port)
1005 1252 2f38 000000009A838300 8029220 Preemptive 00000000B6A99240:00000000B6A99800 00000000002f1070 0 MTA (Threadpool Completion Port)
1006 1317 3118 000000001C2E5120 8029220 Preemptive 00000000B6DA3A30:00000000B6DA4440 00000000002f1070 0 MTA (Threadpool Completion Port)
1007 1837 3120 000000009A8375E0 8029220 Preemptive 00000000B6D38F10:00000000B6D394D0 00000000002f1070 0 MTA (Threadpool Completion Port)
1009 1964 2f64 000000009A81DEF0 1029220 Preemptive 0000000000000000:0000000000000000 00000000002f1070 0 MTA (Threadpool Worker)可以看到当前有 1006 个线程其中 1000 个是 Threadpool Completion Port这么多IO线程卡死也是第一次遇到。说实话看到 Threadpool Completion Port 我就想到这是一个异步操作的回调那为什么会有这么多IO线程被卡死 ? 要想寻找答案抽个线程看一下。0:1000 ~1000s
ntdll!NtNotifyChangeDirectoryFile0xa:
0000000077c7a75a c3 ret
0:1000 !clrstack
OS Thread Id: 0x1704 (1000)Child SP IP Call Site
00000000A99FF4C0 0000000077c7a75a [InlinedCallFrame: 00000000a99ff4c0] InteropKernel32.ReadDirectoryChangesW(Microsoft.Win32.SafeHandles.SafeFileHandle, Byte[], Int32, Boolean, Int32, Int32 ByRef, System.Threading.NativeOverlapped*, IntPtr)
00000000A99FF4C0 000007fe8e87bd20 [InlinedCallFrame: 00000000a99ff4c0] InteropKernel32.ReadDirectoryChangesW(Microsoft.Win32.SafeHandles.SafeFileHandle, Byte[], Int32, Boolean, Int32, Int32 ByRef, System.Threading.NativeOverlapped*, IntPtr)
00000000A99FF470 000007fe8e87bd20 DomainBoundILStubClass.IL_STUB_PInvoke(Microsoft.Win32.SafeHandles.SafeFileHandle, Byte[], Int32, Boolean, Int32, Int32 ByRef, System.Threading.NativeOverlapped*, IntPtr)
00000000A99FF560 000007fef19dab6e System.IO.FileSystemWatcher.Monitor(AsyncReadState) [E:\A\_work\322\s\corefx\src\System.IO.FileSystem.Watcher\src\System\IO\FileSystemWatcher.Win32.cs 141]
00000000A99FF5E0 000007fef19dae6c System.IO.FileSystemWatcher.ReadDirectoryChangesCallback(UInt32, UInt32, System.Threading.NativeOverlapped*) [E:\A\_work\322\s\corefx\src\System.IO.FileSystem.Watcher\src\System\IO\FileSystemWatcher.Win32.cs 227]
00000000A99FF630 000007feedbe0af9 System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object) [E:\A\_work\191\s\src\mscorlib\shared\System\Threading\ExecutionContext.cs 167]
00000000A99FF6B0 000007feede094dc System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32, UInt32, System.Threading.NativeOverlapped*) [E:\A\_work\191\s\src\mscorlib\src\System\Threading\Overlapped.cs 108]
00000000A99FF7F0 000007feee359ed3 [GCFrame: 00000000a99ff7f0]
00000000A99FF9D0 000007feee359ed3 [DebuggerU2MCatchHandlerFrame: 00000000a99ff9d0]我去又见 FileSystemWatcher 追这个系列的朋友应该知道我上个月分析了一篇 记一次 .NET 某流媒体独角兽 API 句柄泄漏分析文件句柄 爆高他的形成原因是 定时刷新 appsetttings reloadOnChangetrue 所致这世界真小莫不会撞车了。。。接下来我们重点关注一下它。2. 探究 FileSystemWatcher要想进一步分析先用 !dso 命令看一下当前的线程栈对象。0:1000 !dso
OS Thread Id: 0x1704 (1000)
RSP/REG Object Name
00000000A99FF508 00000000263285d8 System.Byte[]
00000000A99FF518 00000000242aeb10 System.Threading._IOCompletionCallback
00000000A99FF560 00000000242ae1b0 Microsoft.Win32.SafeHandles.SafeFileHandle
00000000A99FF568 00000000242aeaa8 System.Threading.PreAllocatedOverlapped
00000000A99FF578 00000000242aeb10 System.Threading._IOCompletionCallback
00000000A99FF5E0 00000000242a8538 System.IO.FileSystemWatcher
00000000A99FF5E8 00000000242aea10 System.IO.FileSystemWatcherAsyncReadState
00000000A99FF608 00000000242aea10 System.IO.FileSystemWatcherAsyncReadState
00000000A99FF610 0000000023206e30 System.Threading.ExecutionContext
00000000A99FF618 0000000001032928 System.Threading.ContextCallback
00000000A99FF630 00000000242a8538 System.IO.FileSystemWatcher
00000000A99FF678 00000000b6a69a40 System.Threading.Thread
00000000A99FF688 00000000242aeb10 System.Threading._IOCompletionCallback
00000000A99FF690 0000000023206e30 System.Threading.ExecutionContext
00000000A99FF6C0 0000000021fa55d8 System.Threading._IOCompletionCallback
00000000A99FF6C8 000000002052e6e0 System.Threading.ExecutionContext
00000000A99FF7E0 000000000560d2b0 System.Threading.OverlappedData由于线程栈上的对象是向小扩展的所以看那个最小地址上的 System.Byte[] 内容就知道当前回调的是啥啦截图如下经过上一役的分析经验到这里我基本就搞清楚了这又是一个不断构建 ConfigurationRoot 时配了 reloadOnChange: true 的经典案例它的后果会导致内存中新增大量的 FileSystemWatcher 和 ConfigurationRoot 无法释放而诱发点就是上图中的日志文件的不断变更导致的海量回调函数触发的卡死案例具体详情... 请听我慢慢分解先验证下这两个类在托管堆上的个数。0:1000 !dumpheap -stat -type FileSystemWatcher
Statistics:MT Count TotalSize Class Name
000007fe8ed5bc90 2 160 System.Collections.Generic.Dictionary2[[System.String, System.Private.CoreLib],[System.IO.FileSystemWatcher, System.IO.FileSystem.Watcher]]
000007fe8e9f11a0 34480 1930880 System.IO.FileSystemWatcherAsyncReadState
000007fe8e9d69c8 34480 4137600 System.IO.FileSystemWatcher
Total 68962 objects0:1000 !dumpheap -stat -type ConfigurationRoot
Statistics:MT Count TotalSize Class Name
000007fe8e9f1e70 34480 827520 Microsoft.Extensions.Configuration.ConfigurationRootc__DisplayClass2_0
000007fe8e999560 34480 1103360 Microsoft.Extensions.Configuration.ConfigurationRoot
Total 68960 objects果不其然托管堆有 3.4w 的 FileSystemWatcher 和 ConfigurationRoot接下来就得和朋友沟通了。3. 到底是什么代码引起的?询问朋友为什么会有 3.4w 的 ConfigurationRoot 对象理论上一个程序只会有一个根据这些信息朋友很快就找到了问题代码截图如下就是因为上图中的 reloadOnChange: true 让底层构建了 FileSystemWatcher 对 appsettings.json 的实时监控从而导致内存出现了 3.4w 的对象无法释放。三为什么日志变更会造成程序卡死 1. 当初的困惑其实我当初分析到这里的时候也是很困惑的就算内存中有 3.4w 的 FileSystemWatcher那也只是对 appsettings.json 的监控只要这个文件不变动就不会触发 3.4w 的回调不是吗可当我分析完 ConfigurationRoot 源码之后我发现自己真tmd的天真。2. 从源码中寻找答案首先我们看看 FileSystemWatcher 到底监控的是啥可以在它的构造函数中设一个断点如下图所示很明显的看到它 watch 的是程序根目录这就能解释为什么日志文件有变更就会触发文件变更的回调函数为了验证我可以在 ReadDirectoryChangesCallback 方法中下一个断点再丢一个日志文件到根目录看是否能触发就知道了。。。截图如下回到本案例也就是说一旦有日志变动就会触发 3.4w 个回调函数如果变动100次就会触发 340w 次回调而日志变更不停止自然就会因为海量的回调把程序搞死。。。对吧。。。四总结 本次事故可能是由于朋友偷懒没有将 Configuration 或 IOptions 注下去而是采用重新构建 ConfigurationRoot 的方式获取 ConnectionString并错误的配置 reloadOnChange: true 导致IO线程无法及时处理由于日志文件的变更导致的海量回调函数进而导致程序挂死。知道整个来龙去脉之后优化措施就很简单了提供两种方法。将 reloadOnChange: true 改成 reloadOnChange: false 。想办法将 Configuration 注入到 DataBaseConfig 类中做成静态变量也行 。最后上一个彩蛋朋友太客气了。END工作中的你是否已遇到 ... 1. CPU爆高2. 内存暴涨3. 资源泄漏4. 崩溃死锁5. 程序呆滞等紧急事件全公司都指望着你能解决... 危难时刻才能展现你的技术价值作为专注于.NET高级调试的技术博主欢迎微信搜索: 一线码农聊技术免费协助你分析Dump文件希望我能将你的踩坑经验分享给更多的人。
