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.NET Core 中如何调试死锁 ?

發(fā)布時(shí)間：2023/12/4 asp.net 28 豆豆

生活随笔收集整理的這篇文章主要介紹了 .NET Core 中如何调试死锁 ? 小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,幫大家做個(gè)參考.

這篇文章，我們研究一下如何調(diào)試一個(gè) 死鎖問題，可以下載一下 https://github.com/dotnet/samples/tree/main/core/diagnostics/DiagnosticScenarios 源碼，程序運(yùn)行后，你會(huì)發(fā)現(xiàn)api無響應(yīng)而且線程會(huì)不斷增長(zhǎng)，然后你會(huì)學(xué)習(xí)到用不同的工具去分析這個(gè)死鎖問題。

生成 core dump

為了能找出程序無響應(yīng)的原因，core dump 提供了當(dāng)時(shí)線程的狀態(tài)以及各種存在線程競(jìng)爭(zhēng)的鎖，接下來運(yùn)行如下命令：

dotnet?run

為了能找到進(jìn)程ID，使用如下命令。

dotnet-trace?ps

可以自己查看一下 shell 輸出，我們的進(jìn)程是 4807，你的進(jìn)程號(hào)可能不一樣，接下來訪問URL: https://localhost:5001/api/diagscenario/deadlock ，你會(huì)發(fā)現(xiàn)這個(gè)api請(qǐng)求會(huì)一直得不到response，等 10-15s 后，使用下面的命令收集一個(gè) dump 文件。

dotnet-dump?collect?-p?4807

分析 core dump

為了能夠?qū)ι珊玫?dump 進(jìn)行分析，使用如下命令 dotnet-dump analyze 命令，參考如下：

dotnet-dump?analyze??~/.dotnet/tools/core_20190513_143916

因?yàn)槭且粋€(gè)莫名的無響應(yīng)問題，所以你可能想先對(duì)進(jìn)程中的所有線程有一個(gè)整體的感知。

>?threads *0?0x1DBFF?(121855)1?0x1DC01?(121857)2?0x1DC02?(121858)3?0x1DC03?(121859)4?0x1DC04?(121860)5?0x1DC05?(121861)6?0x1DC06?(121862)7?0x1DC07?(121863)8?0x1DC08?(121864)9?0x1DC09?(121865)10?0x1DC0A?(121866)11?0x1DC0D?(121869)12?0x1DC0E?(121870)13?0x1DC10?(121872)14?0x1DC11?(121873)15?0x1DC12?(121874)16?0x1DC13?(121875)17?0x1DC14?(121876)18?0x1DC15?(121877)19?0x1DC1C?(121884)20?0x1DC1D?(121885)21?0x1DC1E?(121886)22?0x1DC21?(121889)23?0x1DC22?(121890)24?0x1DC23?(121891)25?0x1DC24?(121892)26?0x1DC25?(121893) ... ...317?0x1DD48?(122184)318?0x1DD49?(122185)319?0x1DD4A?(122186)320?0x1DD4B?(122187)321?0x1DD4C?(122188)

輸出中展示了進(jìn)程中的所有線程ID，以及相關(guān)的調(diào)試器線程ID 和操作系統(tǒng)線程ID。

接下來我們有必要了解下每個(gè)線程都在做什么？可以用 clrstack 查看線程棧，為了能查看所有的線程棧，使用如下命令：

clrstack?-all.........Child?SP???????????????IP?Call?Site 00007F2AE37B5680?00007f305abc6360?[GCFrame:?00007f2ae37b5680] 00007F2AE37B5770?00007f305abc6360?[GCFrame:?00007f2ae37b5770] 00007F2AE37B57D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae37b57d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE37B5920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE37B5950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE37B5CA0?00007f30593044af?[GCFrame:?00007f2ae37b5ca0] 00007F2AE37B5D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae37b5d70] OS?Thread?Id:?0x1dc82Child?SP???????????????IP?Call?Site 00007F2AE2FB4680?00007f305abc6360?[GCFrame:?00007f2ae2fb4680] 00007F2AE2FB4770?00007f305abc6360?[GCFrame:?00007f2ae2fb4770] 00007F2AE2FB47D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae2fb47d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE2FB4920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE2FB4950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE2FB4CA0?00007f30593044af?[GCFrame:?00007f2ae2fb4ca0] 00007F2AE2FB4D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae2fb4d70] OS?Thread?Id:?0x1dc83Child?SP???????????????IP?Call?Site 00007F2AE27B3680?00007f305abc6360?[GCFrame:?00007f2ae27b3680] 00007F2AE27B3770?00007f305abc6360?[GCFrame:?00007f2ae27b3770] 00007F2AE27B37D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae27b37d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE27B3920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE27B3950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE27B3CA0?00007f30593044af?[GCFrame:?00007f2ae27b3ca0] 00007F2AE27B3D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae27b3d70] OS?Thread?Id:?0x1dc84Child?SP???????????????IP?Call?Site 00007F2AE1FB2680?00007f305abc6360?[GCFrame:?00007f2ae1fb2680] 00007F2AE1FB2770?00007f305abc6360?[GCFrame:?00007f2ae1fb2770] 00007F2AE1FB27D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae1fb27d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE1FB2920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE1FB2950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE1FB2CA0?00007f30593044af?[GCFrame:?00007f2ae1fb2ca0] 00007F2AE1FB2D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae1fb2d70] OS?Thread?Id:?0x1dc85Child?SP???????????????IP?Call?Site 00007F2AE17B1680?00007f305abc6360?[GCFrame:?00007f2ae17b1680] 00007F2AE17B1770?00007f305abc6360?[GCFrame:?00007f2ae17b1770] 00007F2AE17B17D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae17b17d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE17B1920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE17B1950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE17B1CA0?00007f30593044af?[GCFrame:?00007f2ae17b1ca0] 00007F2AE17B1D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae17b1d70] OS?Thread?Id:?0x1dc86Child?SP???????????????IP?Call?Site 00007F2AE0FB0680?00007f305abc6360?[GCFrame:?00007f2ae0fb0680] 00007F2AE0FB0770?00007f305abc6360?[GCFrame:?00007f2ae0fb0770] 00007F2AE0FB07D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae0fb07d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE0FB0920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE0FB0950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE0FB0CA0?00007f30593044af?[GCFrame:?00007f2ae0fb0ca0] 00007F2AE0FB0D70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae0fb0d70] OS?Thread?Id:?0x1dc87Child?SP???????????????IP?Call?Site 00007F2AE07AF680?00007f305abc6360?[GCFrame:?00007f2ae07af680] 00007F2AE07AF770?00007f305abc6360?[GCFrame:?00007f2ae07af770] 00007F2AE07AF7D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2ae07af7d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2AE07AF920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2AE07AF950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2AE07AFCA0?00007f30593044af?[GCFrame:?00007f2ae07afca0] 00007F2AE07AFD70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2ae07afd70] OS?Thread?Id:?0x1dc88Child?SP???????????????IP?Call?Site 00007F2ADFFAE680?00007f305abc6360?[GCFrame:?00007f2adffae680] 00007F2ADFFAE770?00007f305abc6360?[GCFrame:?00007f2adffae770] 00007F2ADFFAE7D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2adffae7d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2ADFFAE920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2ADFFAE950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2ADFFAECA0?00007f30593044af?[GCFrame:?00007f2adffaeca0] 00007F2ADFFAED70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2adffaed70] ... ... Observing?the?callstacks?for?all?300+?threads?shows?a?pattern?where?a?majority?of?the?threads?share?a?common?callstack:ConsoleCopy OS?Thread?Id:?0x1dc88Child?SP???????????????IP?Call?Site 00007F2ADFFAE680?00007f305abc6360?[GCFrame:?00007f2adffae680] 00007F2ADFFAE770?00007f305abc6360?[GCFrame:?00007f2adffae770] 00007F2ADFFAE7D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2adffae7d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2ADFFAE920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2ADFFAE950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2ADFFAECA0?00007f30593044af?[GCFrame:?00007f2adffaeca0] 00007F2ADFFAED70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2adffaed70]

觀察這超300+ 的線程棧，發(fā)現(xiàn)很多線程都是類似下面的線程棧。

OS?Thread?Id:?0x1dc88Child?SP???????????????IP?Call?Site 00007F2ADFFAE680?00007f305abc6360?[GCFrame:?00007f2adffae680] 00007F2ADFFAE770?00007f305abc6360?[GCFrame:?00007f2adffae770] 00007F2ADFFAE7D0?00007f305abc6360?[HelperMethodFrame_1OBJ:?00007f2adffae7d0]?System.Threading.Monitor.ReliableEnter(System.Object,?Boolean?ByRef) 00007F2ADFFAE920?00007F2FE392B31F?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_1()?[/home/marioh/webapi/Controllers/diagscenario.cs?@?36] 00007F2ADFFAE950?00007F2FE392B46D?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/__w/3/s/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 00007F2ADFFAECA0?00007f30593044af?[GCFrame:?00007f2adffaeca0] 00007F2ADFFAED70?00007f30593044af?[DebuggerU2MCatchHandlerFrame:?00007f2adffaed70]

從調(diào)用棧看，api請(qǐng)求已經(jīng)進(jìn)去了 deadlock 方法，然后在 Monitor.ReliableEnter 處卡住，這就說明有其他線程已經(jīng)進(jìn)去了這個(gè)臨界區(qū)。

接下來我們要尋找到底是哪一個(gè)線程正在持有鎖？可以用 syncblk 來獲取更多線程鎖信息。

>?syncblk Index?????????SyncBlock?MonitorHeld?Recursion?Owning?Thread?Info??????????SyncBlock?Owner43?00000246E51268B8??????????603?????????1?0000024B713F4E30?5634??28???00000249654b14c0?System.Object44?00000246E5126908????????????3?????????1?0000024B713F47E0?51d4??29???00000249654b14d8?System.Object ----------------------------- Total???????????344 CCW?????????????1 RCW?????????????2 ComClassFactory?0 Free????????????0

這里有兩個(gè)列需要注意下：

MonitorHeld

它記錄了這個(gè)持有鎖當(dāng)前有多少持有線程和等待線程。

Owning Thread Info

它表示當(dāng)前持有鎖的線程信息。

到這里，我們看到有兩個(gè)線程 0x5634 和 0x51d4 持有了一個(gè)鎖，接下來可以切到各自線程看看里面到底做了什么？可以用 setthread 和 clrstack 命令。

首先看一下第一個(gè)線程 0x5634，我們發(fā)現(xiàn)它正在獲取一個(gè)鎖，但通過 syncblk 我們知道這個(gè)線程已經(jīng)持有了一個(gè)鎖，這問題就大了，可以想象所有等待這個(gè)持有鎖的線程將會(huì)被無限期等待。

>?setthread?28 >?clrstack OS?Thread?Id:?0x5634?(28)Child?SP???????????????IP?Call?Site 0000004E46AFEAA8?00007fff43a5cbc4?[GCFrame:?0000004e46afeaa8] 0000004E46AFEC18?00007fff43a5cbc4?[GCFrame:?0000004e46afec18] 0000004E46AFEC68?00007fff43a5cbc4?[HelperMethodFrame_1OBJ:?0000004e46afec68]?System.Threading.Monitor.Enter(System.Object) 0000004E46AFEDC0?00007FFE5EAF9C80?testwebapi.Controllers.DiagScenarioController.DeadlockFunc()?[C:\Users\dapine\Downloads\Diagnostic_scenarios_sample_debug_target\Controllers\DiagnosticScenarios.cs?@?58] 0000004E46AFEE30?00007FFE5EAF9B8C?testwebapi.Controllers.DiagScenarioController.<deadlock>b__3_0()?[C:\Users\dapine\Downloads\Diagnostic_scenarios_sample_debug_target\Controllers\DiagnosticScenarios.cs?@?26] 0000004E46AFEE80?00007FFEBB251A5B?System.Threading.ThreadHelper.ThreadStart_Context(System.Object)?[/_/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs?@?44] 0000004E46AFEEB0?00007FFE5EAEEEEC?System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext,?System.Threading.ContextCallback,?System.Object)?[/_/src/System.Private.CoreLib/shared/System/Threading/ExecutionContext.cs?@?201] 0000004E46AFEF20?00007FFEBB234EAB?System.Threading.ThreadHelper.ThreadStart()?[/_/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs?@?93] 0000004E46AFF138?00007ffebdcc6b63?[GCFrame:?0000004e46aff138] 0000004E46AFF3A0?00007ffebdcc6b63?[DebuggerU2MCatchHandlerFrame:?0000004e46aff3a0]

第二個(gè)線程情況類似，剩下的 300+ 線程也差不多都是在這些死鎖的 lock 上無限期的等待。

總結(jié)

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