查看w3wp进程占用的内存及.NET内存泄露,死锁分析

一 基础知识

 在分析之前,先上一张图:

从上面可以看到,这个w3wp进程占用了376M内存,启动了54个线程。

在使用windbg查看之前,看到的进程含有 *32 字样,意思是在64位机器上已32位方式运行w3wp进程。这个可以通过查看IIS Application Pool 的高级选项进行设置:

好了,接下打开Windbg看看这个w3wp进程占用了376M内存,启动的54个线程。

1. 加载 WinDbg SOS 扩展命令

.load C:WindowsMicrosoft.NETFrameworkv2.0.50727sos.dll

2. !dumpheap -stat

!DumpHeap 将遍历 GC 堆对对象进行分析。

  MT            Count    TotalSize       Class Name
78eb9834        1           12       System.ServiceModel.ServiceHostingEnvironment+HostingManager+ExtensionHelper

0118c800      101        14824      Free
...
63ce0004    19841      1111096 System.Reflection.RuntimeMethodInfo
63ce2ee4    11080      2061036 System.Int32[]
63ce0d48    34628      2242596 System.String
63ce37b8    20012      3264884 System.Byte[]
63cb4518   157645      4940676 System.Object[]
Total 524310 objects

可以看到,w3wp上总共有524310个对象, 共占用了这些内存。

我们可以将上述上述列出的这些对象归为2类:

1). 有根对象(在应用程序中对这些对象存在引用)

2). 自从上次垃圾回收之后新创建或无跟对象

要注意的是Free这项:

0118c800      101        14824      Free

这项一般都是GC not yet Compacted的空间或一些堆上分配的禁止GC compacted钉扣对象.

第一栏 : 类型的方法列表 MT(method type for the type)

第二栏:堆上的对象数量

第三栏:所有同类对象的总大小

3. !dumpheap -mt 63ce0d48   

查看 63ce0d48  单元的有哪些对象。

4. !do 103b3360

看看103b3360地址的string包含哪些内容

可见,103b3360地址的字符串value="System.Web.UI.PageRequestManager:AsyncPostBackError", 占120bytes. 这个字符串对象包含3个字段,它们的偏移量分别是4,8,12。

5. dd 103b3360

看看103b3360的值

从左往右第一列是地址,而第二列开始则是地址上的数据。

6. !dumpheap -type String -min 100

看看堆上所有大于100字节的字符串。 注意:假如 -min 85000(大于85000字节的字符串或对象将存储在大对象堆上). 

二. NET内存泄露分析案例

1 基础认识

  .net世界里,GC是负责垃圾回收的,但GC仅仅是回收哪些不可及的对象(无根对象),对于有应用的有根对象,GC对此无能为力。

  .net一些内存泄漏的根本原因:

  • 使用静态引用
  • 未退订的事件-作者认为这是最常见的内存泄漏原因
  • 未退订的静态事件
  • 未调用Dispose方法
  • 使用不彻底的Dispose方法
  • 在Windows Forms中对BindingSource的误用
  • 未在WorkItem/CAB上调用Remove

一些避免内存泄漏的建议:

  • 对象的创建者或拥有者负责销毁对象,而不是使用者
  • 当不再需要一个事件订阅者时退订此事件,为确保安全可以在Dispose方法中退订
  • 当对象不再触发事件时,应该将对象设为null来移除所有的事件订阅者
  • 当模型和视图引用同一个对象时,推荐给视图传递一个此对象的克隆,以防止无法追踪谁在使用哪个对象
  • 对系统资源的访问应该包装在using块中,这将在代码执行后强制执行Dispose

对这些做基本了解后,我们将步入正题。

2. 案例分析

先上测试代码: 

 1 public class LeakTest
 2     {
 3         private static string leakString;
 4 
 5         public LeakTest()
 6         {
 7             for (int i = 0; i < 1000; i++)
 8             {
 9                 leakString += "LEAK";
10             }
11         }
12 
13         public string GetRamdonString()
14         {
15             System.Random random = new System.Random();
16 
17             string str = string.Empty;
18             for (int i = 0; i < 25; i++)
19             {
20                 str += str + random.Next(100);
21             }
22             return str;
23         }
24 
25         public void NoDispose()
26         {
27             string str = GetRamdonString();
28             
29             ZipFile zip = new ZipFile();
30             zip.AddEntry("a.txt", str);
31             zip.AddEntry("b.txt", str);
32             zip.Save("test.rar");
33             //zip.Dispose();
34         }
35     }
36 
37     class Program
38     {
39         static void Main(string[] args)
40         {
41             LeakTest leakTest = new LeakTest();
42             leakTest.NoDispose();
43             Console.ReadLine();
44         }
45     }
View Code

需要说明的是:

这里程序里面定义了一个Static 字符串,及使用了Ionic.Zip 这个Zip压缩包,仅仅是为了模拟内存堆积现象,没有调用zip.Dispose()方法,事实上Ionic.Zip并不会造成内存泄露。

正式开始了:

啊哈,好极了。 运行程序,好家伙,果然很耗费内存! 这么个小程序,吃了287M,并启动了12个线程.

0:005> .load C:WindowsMicrosoft.NETFramework64v2.0.50727sos.dll 
0:005> .load C:Symbolssosex_64sosex.dll

0:005> !dumpheap -stat

 1 0:012> !dumpheap -stat
 2 PDB symbol for mscorwks.dll not loaded
 3 total 12840 objects
 4 Statistics:
 5               MT    Count    TotalSize Class Name
 6 000007ff001d2248        1           24 System.Collections.Generic.Dictionary`2+ValueCollection[[System.String, mscorlib],[Ionic.Zip.ZipEntry, Ionic.Zip.Reduced]]
 7 000007ff000534f0        1           24 ZipTest.LeakTest
 8 000007fee951e8e8        1           24 System.IO.TextReader+NullTextReader
 9 000007fee94f8198        1           24 System.Security.Cryptography.RNGCryptoServiceProvider

11 ...
43 000007ff001d9130 1041 66624 Ionic.Zlib.DeflateManager+CompressFunc 44 000007fee94d2d40 1023 73656 System.Threading.ExecutionContext 45 000007fee951e038 3075 1387592 System.UInt32[] 46 000007fee951ca10 3179 2450704 System.Int16[] 47 0000000000207800 261 67034512 Free 48 000007fee94d7d90 514 134251544 System.String 49 000007fee94dfdd0 102 138593344 System.Byte[] 50 Total 12840 objects

果然,我们看到了里面有2类大对象,分别占用了134M和138M . 好家伙!

0:005> !dumpheap -mt 

  1 0:012> !dumpheap -mt 000007fee94dfdd0      
  2          Address               MT     Size
  3...   
 24 00000000026f11f0 000007fee94dfdd0    65560     
 25 0000000002701288 000007fee94dfdd0    65560     
 26 00000000027112a0 000007fee94dfdd0    65592     
 27 0000000002722b50 000007fee94dfdd0    65560     
 28 0000000002752b98 000007fee94dfdd0    65560     
 29 ...    
 47 000000000290ab98 000007fee94dfdd0    65560     
 48 000000000293abe0 000007fee94dfdd0    65560     
 49 ...     
 64 0000000002ac1378 000007fee94dfdd0    65560     
 65 0000000002ad1410 000007fee94dfdd0    65560     
 66...  
103 00000000165a71e0 000007fee94dfdd0 67108888     
104 0000000027c11000 000007fee94dfdd0 67108888     
105 total 102 objects
106 Statistics:
107               MT    Count    TotalSize Class Name
108 000007fee94dfdd0      102    138593344 System.Byte[]
109 Total 102 objects


果然,有那么多65592和65560啊 啊

随便找一个看一下:

0:005> !do 0000000002ba4790

1 0:012> !do 0000000002ba4790 
2 Name: System.Byte[]
3 MethodTable: 000007fee94dfdd0
4 EEClass: 000007fee90e26b0
5 Size: 65590(0x10036) bytes
6 Array: Rank 1, Number of elements 65566, Type Byte
7 Element Type: System.Byte
8 Fields:
9 None

哦。这是个一维的数组,有65566字节,推测应该好像是short(int16)长度。

继续,

!gcroot 0000000002b42dd0

0:012> !gcroot 0000000002b42dd0 
Note: Roots found on stacks may be false positives. Run "!help gcroot" for
more info.
Scan Thread 0 OSTHread 1d3c
RSP:18ef58:Root:00000000025c5b88(Ionic.Zip.ZipFile)->
00000000025d2578(Ionic.Zlib.ParallelDeflateOutputStream)->
00000000025dc528(System.Collections.Generic.List`1[[Ionic.Zlib.WorkItem, Ionic.Zip.Reduced]])->
000000000294ac38(System.Object[])->
0000000002b32d78(Ionic.Zlib.WorkItem)->
0000000002b42dd0(System.Byte[])
...
Scan Thread 10 OSTHread 3718

这里有点看头了! 看其跟对象 Ionic.Zip.ZipFile 这个对象占着没销毁的内存呢!

 RSP:18ef58:Root:00000000025c5b88(Ionic.Zip.ZipFile)->
00000000025d2578(Ionic.Zlib.ParallelDeflateOutputStream)->
00000000025dc528(System.Collections.Generic.List`1[[Ionic.Zlib.WorkItem, Ionic.Zip.Reduced]])->
000000000294ac38(System.Object[])->
0000000002b32d78(Ionic.Zlib.WorkItem)->
0000000002b42dd0(System.Byte[])

换一个看看:

0:012> !gcroot 00000000029bc730 
Note: Roots found on stacks may be false positives. Run "!help gcroot" for
more info.
Scan Thread 0 OSTHread 1d3c
RSP:18ef58:Root:00000000025c5b88(Ionic.Zip.ZipFile)->
00000000025d2578(Ionic.Zlib.ParallelDeflateOutputStream)->
00000000025dc528(System.Collections.Generic.List`1[[Ionic.Zlib.WorkItem, Ionic.Zip.Reduced]])->
000000000294ac38(System.Object[])->
00000000029ac6d8(Ionic.Zlib.WorkItem)->
00000000029bc730(System.Byte[])
...
Scan Thread 10 OSTHread 3718

查看下其代龄:

0:012> !gcgen 00000000029bc730
GEN 1

看到了,这个byte[]在1代。

到此为止,还记得有个静态字符串吧

private static string leakString;

我们回头再去看看,

 !dumpheap -type String -min 1000

0:012> !dumpheap -type String -min 1000
         Address               MT     Size
00000000025c26e0 000007fee94d7d90     8032     
00000000025cca30 000007fee94d7d90     1176     
00000000025cd308 000007fee94d7d90     1600     
000000001ae81000 000007fee94d7d90 134215704     
total 4 objects
Statistics:
              MT    Count    TotalSize Class Name
000007fee94d7d90        4    134226512 System.String
Total 4 objects

Next,

0:012> !do 00000000025c26e0

0:012> !do 00000000025c26e0 
Name: System.String
MethodTable: 000007fee94d7d90
EEClass: 000007fee90de560
Size: 8026(0x1f5a) bytes
 (C:WindowsassemblyGAC_64mscorlib2.0.0.0__b77a5c561934e089mscorlib.dll)
String: LEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKL....
EAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAK Fields: MT Field Offset Type VT Attr Value Name 000007fee94df000
4000096 8 System.Int32 1 instance 4001 m_arrayLength 000007fee94df000 4000097 c System.Int32 1 instance 4000 m_stringLength 000007fee94d97d8 4000098 10 System.Char 1 instance 4c m_firstChar 000007fee94d7d90 4000099 20 System.String 0 shared static Empty >> Domain:Value 000000000062b1d0:00000000025c1308 << 000007fee94d9688 400009a 28 System.Char[] 0 shared static WhitespaceChars >> Domain:Value 000000000062b1d0:00000000025c1a90 <<

 再看下这个对象:

!dumpobj 00000000025c26e0

0:012> !dumpobj 00000000025c26e0 
Name: System.String
MethodTable: 000007fee94d7d90
EEClass: 000007fee90de560
Size: 8026(0x1f5a) bytes
 (C:WindowsassemblyGAC_64mscorlib2.0.0.0__b77a5c561934e089mscorlib.dll)
(C:WindowsassemblyGAC_64mscorlib2.0.0.0__b77a5c561934e089mscorlib.dll)
String: LEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKL....
EAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAKLEAK Fields:
MT Field Offset Type VT Attr Value Name 000007fee94df000 4000096 8 System.Int32 1 instance 4001 m_arrayLength 000007fee94df000 4000097 c System.Int32 1 instance 4000 m_stringLength 000007fee94d97d8 4000098 10 System.Char 1 instance 4c m_firstChar 000007fee94d7d90 4000099 20 System.String 0 shared static Empty >> Domain:Value 000000000062b1d0:00000000025c1308 << 000007fee94d9688 400009a 28 System.Char[] 0 shared static WhitespaceChars >> Domain:Value 000000000062b1d0:00000000025c1a90 <<

显示结果一样,String:LEAKLEAKLEAKLEAKLEAK......,字符串长度4000,和我们的测试代码吻合:

1  public LeakTest()
2         {
3             for (int i = 0; i < 1000; i++)
4             {
5                 leakString += "LEAK";
6             }
7         }

到此,内存查看分析演示的差不多了!

这里我们演示的是个小得不能再小的程序,且存在前提预期。 假如在实际项目环境中,因为引用的DLL多,生成的对象繁杂,实际诊断问题根源就复杂得多,这就需要比较扎实的基本功。

. 死锁排查

 1. 基础

还是用上面的Console App例子,运行这个程序,启动了13个线程。我们先看一下这13个线程:

!runaway

0:012> !runaway
 User Mode Time
  Thread       Time
   0:5588      0 days 0:00:05.085
   7:4954      0 days 0:00:01.903
   3:4ddc      0 days 0:00:01.825
   8:5af4      0 days 0:00:01.809
   9:4740      0 days 0:00:01.747
  10:6c38      0 days 0:00:01.731
   4:6a94      0 days 0:00:01.700
   5:43ec      0 days 0:00:01.622
   6:8fdc      0 days 0:00:01.606
  12:1e64      0 days 0:00:00.000
  11:6a4       0 days 0:00:00.000
   2:64b4      0 days 0:00:00.000
   1:69e4      0 days 0:00:00.000

恩。13个线程,没错。 这里还可以看到每个线程的执行时间。 其中 0 线程占用时间最多。我们去看下堆栈调用:

~0s

!ClrStack -a

0:012> ~0s
ntdll!ZwRequestWaitReplyPort+0xa:
00000000`77b714da c3              ret
0:000> !ClrStack -a
OS Thread Id: 0x5588 (0)
*** WARNING: Unable to verify checksum for C:WindowsassemblyNativeImages_v2.0.50727_64mscorlibc3beeeb6432f004b419859ea007087f1mscorlib.ni.dll
Child-SP         RetAddr          Call Site
00000000001de670 000007fee9b02c79 DomainNeutralILStubClass.IL_STUB(Microsoft.Win32.SafeHandles.SafeFileHandle, Byte*, Int32, Int32 ByRef, IntPtr)
    PARAMETERS:
        <no data>
        <no data>
        <no data>
        <no data>
        <no data>

00000000001de790 000007fee9b02d92 System.IO.__ConsoleStream.ReadFileNative(Microsoft.Win32.SafeHandles.SafeFileHandle, Byte[], Int32, Int32, Int32, Int32 ByRef)
    PARAMETERS:
        hFile = <no data>
        bytes = <no data>
        offset = <no data>
        count = <no data>
        mustBeZero = <no data>
        errorCode = 0x00000000001de820
    LOCALS:
        <no data>
        0x00000000001de7c0 = 0x0000000000000000
        <no data>
        <no data>

00000000001de7f0 000007fee93f08da System.IO.__ConsoleStream.Read(Byte[], Int32, Int32)
    PARAMETERS:
        this = <no data>
        buffer = <no data>
        offset = <no data>
        count = <no data>
    LOCALS:
        0x00000000001de820 = 0x0000000000000000
        <no data>

00000000001de850 000007fee9412a8a System.IO.StreamReader.ReadBuffer()
    PARAMETERS:
        this = <no data>
    LOCALS:
        <no data>

00000000001de8a0 000007fee9b0622f System.IO.StreamReader.ReadLine()
    PARAMETERS:
        this = <no data>
    LOCALS:
        <no data>
        <no data>
        <no data>
        <no data>

00000000001de8f0 000007ff00190188 System.IO.TextReader+SyncTextReader.ReadLine()
    PARAMETERS:
        this = 0x00000000030387b0

00000000001de950 000007feea23c6a2 ZipTest.Program.Main(System.String[])
    PARAMETERS:
        args = 0x00000000027e2680
    LOCALS:
        0x00000000001de970 = 0x00000000027e26a0
View Code

瞧准了,这是个主线程,他在等待Console.ReadLine(). 所以占用了这么长时间。

再在看一下这13个线程里,哪些是托管堆线程:

!threads

0:012> !threads
ThreadCount: 10
UnstartedThread: 0
BackgroundThread: 9
PendingThread: 0
DeadThread: 0
Hosted Runtime: no
                                              PreEmptive                                                Lock
       ID OSID        ThreadOBJ     State   GC     GC Alloc Context                  Domain           Count APT Exception
   0    1 5588 00000000009d4510      a020 Enabled  00000000030387d0:000000000303a510 00000000009cb1d0     1 MTA
   2    2 64b4 00000000009dc4d0      b220 Enabled  0000000000000000:0000000000000000 00000000009cb1d0     0 MTA (Finalizer)
   3    3 4ddc 0000000000a1a010   180b220 Enabled  0000000002fe1e28:0000000002fe2450 00000000009cb1d0     0 MTA (Threadpool Worker)
   4    4 6a94 0000000000a1d590   180b220 Enabled  0000000002fe73c8:0000000002fe8450 00000000009cb1d0     0 MTA (Threadpool Worker)
   5    5 43ec 0000000000a7bbd0   180b220 Enabled  0000000002fec968:0000000002fee450 00000000009cb1d0     0 MTA (Threadpool Worker)
   6    6 8fdc 0000000000a892b0   180b220 Enabled  0000000002ff0968:0000000002ff2450 00000000009cb1d0     0 MTA (Threadpool Worker)
   7    7 4954 0000000000aa3270   180b220 Enabled  0000000002fee968:0000000002ff0450 00000000009cb1d0     0 MTA (Threadpool Worker)
   8    8 5af4 0000000000a97eb0   180b220 Enabled  0000000002fe8968:0000000002fea450 00000000009cb1d0     0 MTA (Threadpool Worker)
   9    9 4740 0000000000a99400   180b220 Enabled  0000000002fe0358:0000000002fe0450 00000000009cb1d0     0 MTA (Threadpool Worker)
  10    a 6c38 0000000000a9f3a0   180b220 Enabled  0000000002fe3e28:0000000002fe4450 00000000009cb1d0     0 MTA (Threadpool Worker)

在托管堆上启动的线程有10个。这10个线程分别是什么,继续看:

0号MTA: 程序主线程

MTA (Finalizer):这个是Finalizer线程,该线程负责垃圾对象回收。

MTA (Threadpool Worker):这些是ThreadPool创建的线程,这里是Ionic.Zlib.WorkItem产生的工作线程。

另外,CLR根据需要还会开启其他一些线程,如:

并发的GC线程 ,服务器GC线程 ,调试器帮助线程 ,AppDomain卸载线程 等.

看一下同步块情况,有么有死锁?

!syncblk

!dlk

0:003> !dlk
Examining SyncBlocks...
Scanning for ReaderWriterLock instances...
Scanning for holders of ReaderWriterLock locks...
Scanning for ReaderWriterLockSlim instances...
Scanning for holders of ReaderWriterLockSlim locks...
Examining CriticalSections...
No deadlocks detected.

显示该程序没有锁相关资源,实际确实没有。

2 死锁

Lock:lock 关键字将语句块标记为临界区,方法是获取给定对象的互斥锁,执行语句,然后释放该锁。 下面的示例包含一个 lock 语句。

lock 关键字可确保当一个线程位于代码的临界区时,另一个线程不会进入该临界区。 如果其他线程尝试进入锁定的代码,则它将一直等待(即被阻止),直到该对象被释放。

通常,应避免锁定 public 类型,否则实例将超出代码的控制范围。 常见的结构 lock (this)、lock (typeof (MyType)) 和 lock ("myLock") 违反此准则:

  • 如果实例可以被公共访问,将出现 lock (this) 问题。

  • 如果 MyType 可以被公共访问,将出现 lock (typeof (MyType)) 问题。

  • 由于进程中使用同一字符串的任何其他代码都将共享同一个锁,所以出现 lock("myLock") 问题。

最佳做法是定义 private 对象来锁定, 或 private static 对象变量来保护所有实例所共有的数据。

3 案例分析

这个案例很简单,上菜:

 1   public class Consumer1
 2     {
 3         private string connString;
 4         public Consumer1(string str)
 5         {
 6             this.connString = str;
 7         } 
 8     }
 9 
10     public class Consumer2
11     {
12         private string connString;
13         public Consumer2(string str)
14         {
15             this.connString = str;
16         }
17     }
18 
19     class Program
20     {
21         private static Consumer1 consumer1;
22         private static Consumer2 consumer2;
23 
24         static void Main(string[] args)
25         {
26             consumer1 = new Consumer1("Conn1");
27             consumer2 = new Consumer2("Conn2");
28 
29             Thread thread = new Thread(Proc);
30             thread.Start();
31              
32             lock (consumer2)
33             {
34                 Console.WriteLine("Proc->Lock consumer2");
35                 Thread.Sleep(1000);
36                 lock (consumer1)
37                 {
38                     Console.WriteLine("Proc->Lock consumer2->Lock consumer1 ");
39                 }
40             }
41 
42         }
43 
44         private static void Proc()
45         {
46             lock (consumer1)
47             {
48                 Console.WriteLine("Proc->Lock consumer1");
49                 Thread.Sleep(1000);
50                 lock (consumer2)
51                 {
52                     Console.WriteLine("Proc->Lock consumer1->Lock consumer2 ");
53                 }
54             }
55 
56         }
57     }
View Code

运行程序,便进入死锁。

ok,上 windbg.

.load C:Symbolssosex_64sosex.dll

0:000> !dlk

 

 1 0:000> !dlk
 2 Examining SyncBlocks...
 3 Scanning for ReaderWriterLock instances...
 4 Scanning for holders of ReaderWriterLock locks...
 5 Scanning for ReaderWriterLockSlim instances...
 6 Scanning for holders of ReaderWriterLockSlim locks...
 7 Examining CriticalSections...
 8 Scanning for threads waiting on SyncBlocks...
 9 *** WARNING: Unable to verify checksum for D:TestPInvokeCPPTestinDebugTest.exe
10 Scanning for threads waiting on ReaderWriterLock locks...
11 Scanning for threads waiting on ReaderWriterLocksSlim locks...
12 Scanning for threads waiting on CriticalSections...
13 *DEADLOCK DETECTED*
14 CLR thread 0x3 holds the lock on SyncBlock 0000000000c94690 OBJ:00000000027736b8[Test.Consumer1]
15 ...and is waiting for the lock on SyncBlock 0000000000c946d8 OBJ:00000000027736d0[Test.Consumer2]
16 CLR thread 0x1 holds the lock on SyncBlock 0000000000c946d8 OBJ:00000000027736d0[Test.Consumer2]
17 ...and is waiting for the lock on SyncBlock 0000000000c94690 OBJ:00000000027736b8[Test.Consumer1]
18 CLR Thread 0x3 is waiting at Test.Program.Proc()(+0x31 IL,+0x98 Native) [D:TestPInvokeCPPTestProgram.cs @ 60,17]
19 CLR Thread 0x1 is waiting at Test.Program.Main(System.String[])(+0x68 IL,+0x196 Native) [D:TestPInvokeCPPTestProgram.cs @ 46,17]
20 
21 
22 1 deadlock detected.

只需敲一个命令,死锁就检测到了。 注意下面这些地址:

0000000000c94690 OBJ:00000000027736b8
0000000000c946d8 OBJ:00000000027736d0
0000000000c946d8 OBJ:00000000027736d0
0000000000c94690 OBJ:00000000027736b8

!mdt 00000000027736b8 看下,把这四个地址都看下:
 1 0:000> !mdt 00000000027736b8
 2 00000000027736b8 (Test.Consumer1)
 3     connString:00000000027735b8 (System.String) Length=5, String="Conn1"
 4 0:000> !mdt 00000000027736d0
 5 00000000027736d0 (Test.Consumer2)
 6     connString:00000000027735e0 (System.String) Length=5, String="Conn2"
 7 0:000> !mdt 00000000027736d0
 8 00000000027736d0 (Test.Consumer2)
 9     connString:00000000027735e0 (System.String) Length=5, String="Conn2"
10 0:000> !mdt 00000000027736b8
11 00000000027736b8 (Test.Consumer1)
12     connString:00000000027735b8 (System.String) Length=5, String="Conn1"
明了了。
对比下上面那个程序,瞧一瞧,是不是这几个对像,连对象里的字符串值都一览无余!


 
 
原文地址:https://www.cnblogs.com/startpoint/p/4194052.html