.Net 内存转储中的大量死线程

本文介绍了.Net 内存转储中的大量死线程的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

在分析 .Net4.5 WCF w3wp 进程的内存转储过程中，我遇到了许多标识为死的线程.!threads 显示 107 个线程中有 68 个已死，这似乎相当高.我想知道这些线程是否可以容纳大量内存，因为进程最终会高达 20GB+ 并且似乎永远不会停止.

我如何检查这些线程并查看这些线程持有的对象/内存?有这么多正常吗?

0:000>!threads线程数:107未启动线程:0背景主题:35待处理线程:0死线:68托管运行时:否ID OSID ThreadOBJ 状态 GC 模式 GC 分配上下文域计数 Apt 异常7 1 16fc 0000009d253a36e0 28220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn14 2 a64 000000a1702d7560 2b220 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(终结器)XXXX 3 0 000000a1702f9390 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 4 0 000000a1702fa270 8038820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)16 6 21c8 000000a17031f310 102a220 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池)17 7 2af4 000000a170327ef0 21220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn19 9 1b50 000000a1703cccd0 1020220 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)21 10 85c 000000a170416570 202b020 抢先 000000A0945502B8:000000A094550FD0 000000a1703360c0 0 MTA25 11 13cc 000000a1711823f0 202b020 抢先 000000A094554D60:000000A094554FD0 000000a1703360c0 0 MTA26 12 2044 000000a1711921d0 3029220 抢占式 0000000000000000:0000000000000000 000000a1703360c0 0 MTA(线程池)XXXX 16 0 000000a17128a690 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 17 0 000000a1712bd610 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 18 0 000000a1712c5e30 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 19 0 000000a1712c4e90 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)2 20 8a4 000000a1712c6600 20220 抢占式 0000009E8B81C238:0000009E8B81DFD0 0000009d25385d70 0 Ukn18 21 28f8 000000a1712c3720 20220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 022 22 bfc 000000a1712c3ef0 20220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn20 23 257c 000000a1712c5660 20220 先发制人 000000A09457AC30:000000A09457AFD0 0000009d25385d70 0 Ukn23 24 13e0 000000a1712c6dd0 20220 抢先 0000009F87F0B5C8:0000009F87F0CFD0 0000009d25385d70 0 UknXXXX 26 0 000000a1713d8fb0 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)28 27 2aac 000000a1713dbe90 a029220 抢占式 0000000000000000:0000000000000000 000000a1703360c0 0 端口(线程池完成)XXXX 29 0 000000a1713dc660 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)29 30 284c 000000a1713d9f50 202b220 抢先 0000000000000000:0000000000000000 000000a1703360c0 0 MTAXXXX 31 0 000000a1713da720 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)XXXX 32 0 000000a1713db6c0 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 33 0 000000a174347600 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 34 0 000000a174344720 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 35 0 000000a174345e90 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 36 0 000000a174346660 39820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 UknXXXX 37 0 000000a174346e30 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成)XXXX 38 0 000000a1743456c0 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 39 0 000000a1741b9d10 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 40 0 000000a1741bc420 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 41 0 000000a1741bcbf0 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 42 0 000000a1741ba4e0 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)XXXX 43 0 000000a1741be360 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)3 44 1e94 000000a1741bd3c0 20220 先发制人 0000009F87E511F8:0000009F87E52FD0 0000009d25385d70 0 UknXXXX 45 0 000000a1741bdb90 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)35 46 12dc 000000a1741bacb0 20220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 MTAXXXX 47 0 000000a1741beb30 30820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 UknXXXX 48 0 000000a1741bf300 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)XXXX 49 0 000000a171171f40 8039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 端口(线程池完成)36 50 2bb4 000000a171173e80 202b020 抢先 0000000000000000:0000000000000000 000000a1703360c0 0 MTA37 51 9e4 000000a171177530 202b020 抢先 000000A0945528D0:000000A094552FD0 000000a1703360c0 0 MTA39 53 6d0 000000a171174e20 21220 先发制人 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn40 54 f34 000000a171172ee0 21220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn41 55 f74 000000a1711755f0 21220 先发制人 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn42 56 2198 000000a171174650 21220 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 0XXXX 57 0 000000a171175dc0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 60 0 000000a171176590 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 62 0 000000a171177d00 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 64 0 000000a171178ca0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 65 0 000000a1741bfad0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 70 0 000000a174344ef0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 71 0 000000a1713d9780 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 69 0 000000a171171770 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 68 0 000000a1711736b0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 67 0 000000a171172710 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 66 0 000000a171176d60 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 59 0 000000a1711784d0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 58 0 000000a1741bbc50 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 63 0 000000a1741c1240 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 61 0 000000a1741c02a0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 28 0 000000a1741c0a70 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 25 0 000000a1712c46c0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 15 0 000000a1713daef0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 14 0 000000a174347dd0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 13 0 000000a16744b400 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 52 0 000000a167448520 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 8 0 000000a16744bbd0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 72 0 000000a16744ac30 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)XXXX 73 0 000000a16744a460 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 74 0 000000a171268f50 1039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 75 0 000000a1712658a0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 76 0 000000a171269720 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 77 0 000000a171266070 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 78 0 000000a1712677e0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 79 0 000000a171269ef0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 80 0 000000a171266840 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 81 0 000000a17126a6c0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 82 0 000000a171267010 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 83 0 000000a17126ae90 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)XXXX 5 0 000000a171268780 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池完成端口)43 84 dcc 000000a17126b660 8029220 抢占式 0000009D9D1B3B88:0000009D9D1B3FD0 0000009d25385d70 0 端口(线程池完成)XXXX 85 0 000000a171267fb0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 86 0 000000a17126be30 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)46 87 1e54 000000a17126c600 1029220 抢占式 000000A094575068:000000A094576FD0 0000009d25385d70 0 MTA(线程池工作者)XXXX 88 0 000000a17126cdd0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)45 89 1db8 000000a16744c3a0 1029220 抢占式 000000A094577250:000000A094578FD0 0000009d25385d70 0 MTA(线程池工作者)XXXX 90 0 000000a167448cf0 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)XXXX 91 0 000000a16744cb70 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 92 0 000000a1674494c0 1039820 抢先 0000000000000000:0000000000000000 0000009d25385d70 0 MTA(线程池工作者)XXXX 93 0 000000a16744d340 1039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池工作者)50 94 15a4 000000a16744db10 1029220 抢占式 000000A09456AF80:000000A09456AFD0 0000009d25385d70 0 MTA(线程池工作者)47 95 29c8 000000a167449c90 1029220 抢占式 000000A094573D08:000000A094574FD0 0000009d25385d70 0 MTA(线程池工作者)48 96 28c4 000000a16744e2e0 1029220 抢占式 000000A094548ED8:000000A094548FD0 0000009d25385d70 0 MTA(线程池工作者)49 97 69c 000000a16744eab0 1029220 抢占式 0000009D9D1863F0:0000009D9D187FD0 0000009d25385d70 0 MTA(线程池工作者)XXXX 98 0 000000a16744fa50 8039820 抢占式 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn(线程池完成端口)51 99 2bac 000000a16744f280 8029220 抢占式 0000009F87F32660:0000009F87F32FD0 0000009d25385d70 0 MTA 端口(线程池完成)52 101 c40 000000a174599040 1029220 抢占式 0000009D9D178538:0000009D9D179FD0 0000009d25385d70 0 MTA(线程池工作者)54 102 1e5c 000000a174598870 1029220 抢占式 0000009F87F51578:0000009F87F52FD0 0000009d25385d70 0 MTA(线程工作者)56 103 2b68 000000a174596930 1029220 抢占式 0000009D9D188E70:0000009D9D189FD0 0000009d25385d70 0 MTA(线程工作者)55 104 2924 000000a174595990 1029220 抢占式 0000009D9D18C290:0000009D9D18DFD0 0000009d25385d70 0 MTA(线程工作者)53 105 2f0 000000a174599810 1029220 抢占式 0000009E8B89EFD0:0000009E8B89FFD0 0000009d25385d70 0 MTA(线程池工作者)57 106 f5c 000000a174596160 1029220 抢占式 0000009E8B894828:0000009E8B895FD0 0000009d25385d70 0 MTA(线程池工作者)58 107 20c 000000a174599fe0 1029220 抢占式 0000009F87F53258:0000009F87F54FD0 0000009d25385d70 0 MTA(线程池工作者)60 100 1f60 000000a17459a7b0 8029220 抢占式 0000009F87F7B1A8:0000009F87F7CFD0 0000009d25385d70 0 端口(线程)组件池

解决方案

我想知道这些线程是否可以容纳大量内存

记住以下规则:进程提供内存，线程消耗CPU时间.反之亦然:进程不运行，线程不持有内存.如果有人说我的进程仍在运行"，那是对我的进程至少有一个仍在运行的线程"这句话的简化.

死线程(用XXXX标记)表示内存中有一个.NETThread对象和真实"线程(由操作维护的内核对象)系统)不见了.

以下是针对这种情况的 MCVE:

使用系统；使用 System.Collections.Generic;使用 System.Threading;命名空间 DeadThreadExample{课程计划{静态列表AllThreadsIEverStarted = new List();静态无效主(){for(int i=0; i<1000; i++){线程 t = 新线程(DoNothing);t.开始();AllThreadsIEverStarted.Add(t);t.Join();}Console.WriteLine("现在应该有 1000 个死线程.用 WinDbg 和 SOS 调试它！threads");Console.ReadLine();}私有静态无效 DoNothing(){//根本不值一提}}}

调试会话是:

0:006>!threads未加载 clr.dll 的 PDB 符号线程数:1002未启动线程:0背景主题:1待处理线程:0死线程:1000托管运行时:否[...]

可以容纳大量内存

0:006>!dumpheap -stat统计数据:MT 计数 TotalSize 类名[...]53dde9b0 1000 20000 System.Threading.ThreadHelper53d66bf0 1000 44000 System.Threading.ExecutionContext53d62e10 1001 52052 System.Threading.Thread53dad5cc 2000 64000 System.Threading.ThreadStart

所以，是的，如果您将静态集合称为泄漏，则存在内存泄漏".也许这不是泄漏，因为您在某个时间点需要该信息.一旦集合被清除，它就不再是泄漏.

1000 个死线程相当于 ~180 kB 的内存泄漏".我不会称之为大量".即使你传递一个对象作为参数(使用ParameterizedThreadStart)，似乎没有设置Thread对象的属性m_ThreadStartArg，所以我几乎看不到更多的内存会如何泄漏.

如果您不喜欢这种情况，请使用内存分析器并找出哪些 GC 根仍然引用这些线程.

有这么多正常吗?

也许你只是不走运.它们可能会随着下一次垃圾回收而消失.

如何检查这些线程并查看这些线程持有的对象/内存?

使用!dumpheap -stat -type，然后dumpheap -mt，然后!do:

0:006>!dumpheap -stat -type 线程统计数据:MT 计数 TotalSize 类名[...]53d62e10 1001 52052 System.Threading.Thread0:006>!dumpheap -mt 53d62e10地址 MT 大小02ec247c 53d62e10 5202ec2504 53d62e10 52[...]统计数据:MT 计数 TotalSize 类名53d62e10 1001 52052 System.Threading.Thread共 1001 个对象0:006>!do 02ec247c名称: System.Threading.Thread方法表:53d62e10EEClass: 53e679a4大小:52(0x34) 字节文件:C:WINDOWSMicrosoft.NetassemblyGAC_32mscorlibv4.0_4.0.0.0__b77a5c561934e089mscorlib.dll领域:MT 字段偏移类型 VT Attr 值名称53d6cd68 400192d 4 ....Contexts.Context 0 实例 00000000 m_Context53d66bf0 400192e 8 ....ExecutionContext 0 实例 00000000 m_ExecutionContext53d624e4 400192f c System.String 0 实例 00000000 m_Name53d63c70 4001930 10 System.Delegate 0 实例 00000000 m_Delegate53d65074 4001931 14 ...ation.CultureInfo 0 实例 00000000 m_CurrentCulture53d65074 4001932 18 ...ation.CultureInfo 0 实例 00000000 m_CurrentUICulture53d62734 4001933 1c System.Object 0 实例 00000000 m_ThreadStartArg53d67b18 4001934 20 System.IntPtr 1 实例 11519f8 DONT_USE_InternalThread53d642a8 4001935 24 System.Int32 1 实例 2 m_Priority53d642a8 4001936 28 System.Int32 1 实例 3 m_ManagedThreadId53d6878c 4001937 2c System.Boolean 1 实例 0 m_ExecutionContextBelongsToOuterScope[ ... 静止的 ... ]

during the analysis of a memory dump for a .Net4.5 WCF w3wp process, I encountered many threads identified as dead. !threads shows 68 out of 107 threads are dead which appear to be quite high. I was wondering if these threads could hold large amount of memory since the process eventually goes as high as 20GB+ and seem to never go down.

How can I inspect such threads and see the objects/memory held by these? Is it normal to have so many?

0:000> !threads ThreadCount: 107 UnstartedThread: 0 BackgroundThread: 35 PendingThread: 0 DeadThread: 68 Hosted Runtime: no ID OSID ThreadOBJ State GC Mode GC Alloc Context Domain Count Apt Exception 7 1 16fc 0000009d253a36e0 28220 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 14 2 a64 000000a1702d7560 2b220 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Finalizer) XXXX 3 0 000000a1702f9390 8039820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Completion Port) XXXX 4 0 000000a1702fa270 8038820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn (Threadpool Completion Port) 16 6 21c8 000000a17031f310 102a220 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Worker) 17 7 2af4 000000a170327ef0 21220 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn 19 9 1b50 000000a1703cccd0 1020220 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 Ukn (Threadpool Worker) 21 10 85c 000000a170416570 202b020 Preemptive 000000A0945502B8:000000A094550FD0 000000a1703360c0 0 MTA 25 11 13cc 000000a1711823f0 202b020 Preemptive 000000A094554D60:000000A094554FD0 000000a1703360c0 0 MTA 26 12 2044 000000a1711921d0 3029220 Preemptive 0000000000000000:0000000000000000 000000a1703360c0 0 MTA (Threadpool Worker) XXXX 16 0 000000a17128a690 8039820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Completion Port) XXXX 17 0 000000a1712bd610 8039820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Completion Port) XXXX 18 0 000000a1712c5e30 8039820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Completion Port) XXXX 19 0 000000a1712c4e90 8039820 Preemptive 0000000000000000:0000000000000000 0000009d25385d70 0 MTA (Threadpool Completion Port) 2 20 8a4 000000a1712c6600 20220 Preemptive 0000009E8B81C238:0000009E8B81DFD0 0000009d25385d70 0 Ukn 18 21 28f8 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解决方案

I was wondering if these threads could hold large amount of memory

Remember the following rule: a process provides memory, a thread consumes CPU time. The inverse is also true: a process does not run and a thread does not hold memory. If someone says "my process still runs", that's a simplification of the sentence "my process has at least one thread that still runs".

A dead thread (marked with XXXX) means that there is a .NET Thread object in memory and the "real" thread (the kernel object maintained by the operating system) is gone.

The following is an MCVE for that situation:

using System; using System.Collections.Generic; using System.Threading; namespace DeadThreadExample { class Program { static List<Thread> AllThreadsIEverStarted = new List<Thread>(); static void Main() { for(int i=0; i<1000; i++) { Thread t = new Thread(DoNothing); t.Start(); AllThreadsIEverStarted.Add(t); t.Join(); } Console.WriteLine("There should be 1000 dead threads now. Debug it with WinDbg and SOS !threads"); Console.ReadLine(); } private static void DoNothing() { // Just nothing } } }

The debugging session is:

0:006> !threads PDB symbol for clr.dll not loaded ThreadCount: 1002 UnstartedThread: 0 BackgroundThread: 1 PendingThread: 0 DeadThread: 1000 Hosted Runtime: no [...]

could hold large amount of memory

0:006> !dumpheap -stat Statistics: MT Count TotalSize Class Name [...] 53dde9b0 1000 20000 System.Threading.ThreadHelper 53d66bf0 1000 44000 System.Threading.ExecutionContext 53d62e10 1001 52052 System.Threading.Thread 53dad5cc 2000 64000 System.Threading.ThreadStart

So, yes, there is a "memory leak", if you call the static collection a leak. Maybe it's not a leak, because you need that information at some point in time. Once the collection is cleared, it's no longer a leak.

1000 dead threads is equivalent to ~180 kB "memory leak". I wouldn't call that "large amount". Even if you pass an object as an argument (use ParameterizedThreadStart), it seems that the property m_ThreadStartArg of the Thread object is not set, so I can hardly see how a larger amount of memory would be leaked.

If you don't like that situation, use a memory profiler and find out which GC roots still has a reference to those threads.

Is it normal to have so many?

Maybe you were just unlucky. They might all be gone with the next garbage collection.

How can I inspect such threads and see the objects/memory held by these?

Use !dumpheap -stat -type, then dumpheap -mt and then !do:

0:006> !dumpheap -stat -type Thread Statistics: MT Count TotalSize Class Name [...] 53d62e10 1001 52052 System.Threading.Thread 0:006> !dumpheap -mt 53d62e10 Address MT Size 02ec247c 53d62e10 52 02ec2504 53d62e10 52 [...] Statistics: MT Count TotalSize Class Name 53d62e10 1001 52052 System.Threading.Thread Total 1001 objects 0:006> !do 02ec247c Name: System.Threading.Thread MethodTable: 53d62e10 EEClass: 53e679a4 Size: 52(0x34) bytes File: C:WINDOWSMicrosoft.NetassemblyGAC_32mscorlibv4.0_4.0.0.0__b77a5c561934e089mscorlib.dll Fields: MT Field Offset Type VT Attr Value Name 53d6cd68 400192d 4 ....Contexts.Context 0 instance 00000000 m_Context 53d66bf0 400192e 8 ....ExecutionContext 0 instance 00000000 m_ExecutionContext 53d624e4 400192f c System.String 0 instance 00000000 m_Name 53d63c70 4001930 10 System.Delegate 0 instance 00000000 m_Delegate 53d65074 4001931 14 ...ation.CultureInfo 0 instance 00000000 m_CurrentCulture 53d65074 4001932 18 ...ation.CultureInfo 0 instance 00000000 m_CurrentUICulture 53d62734 4001933 1c System.Object 0 instance 00000000 m_ThreadStartArg 53d67b18 4001934 20 System.IntPtr 1 instance 11519f8 DONT_USE_InternalThread 53d642a8 4001935 24 System.Int32 1 instance 2 m_Priority 53d642a8 4001936 28 System.Int32 1 instance 3 m_ManagedThreadId 53d6878c 4001937 2c System.Boolean 1 instance 0 m_ExecutionContextBelongsToOuterScope [ ... static ... ]