My multi-threaded application in C # 2.0 using threadpool hangs every few weeks or so in prod.
I made syncblk
! syncblk
Index SyncBlock MonitorHeld Recursion Owning Thread Info SyncBlock Owner
201 05b9493c 979 1 05bc1040 bcc 45 022f3490 System.Collections.ArrayList
2875 05b4c914 1 1 17b99e10 1af8 290 024862d8 MyProg.MyChildClass
3045 05b4dbec 1 1 17ca7e98 1990 664 02392120 MyProg.MyChildClass
3046 05b4dc1c 1 1 17ca8668 1038 666 02394b00 MyProg.MyChildClass
3194 05b4f80c 3 1 05b5b638 1594 31 02537b88 MyProg.MyChildClass
3072 05b4e114 1 1 17d660f0 1120 848 023dd578 MyProg.MyChildClass
3073 05b4e144 1 1 17c45c30 1884 518 023dfc2c MyProg.MyChildClass
3390 05b51cfc 3 1 16cefcc0 1350 102 02768868 MyProg.MyChildClass
3072 05b4e114 1 1 17d660f0 1120 848 023dd578 MyProg.MyChildClass
3073 05b4e144 1 1 17c45c30 1884 518 023dfc2c MyProg.MyChildClass
I deleted hundreds of lines that look like this:
3073 05b4e144 1 1 17c45c30 1884 518 023dfc2c MyProg.MyChildClass
Thread monitoring, containing 979 monitors, is an arraylist lock, but all the other threads that are waiting are trying to get a reader on another object.
I know which lock is all the reads that are trying to get, but I do not know who holds this lock. How do I find this?
MonitorHeld = 1 clrstack dso.
dso clrstack 979 (id = 45) (id = 290). ,
~ * e! clrstack
Monitor.Enter , clrstack 2
0:000> ~45e !clrstack
OS Thread Id: 0xbcc (45)
ESP EIP
17fbe590 77d2013d [GCFrame: 17fbe590]
17fbe6cc 77d2013d [HelperMethodFrame: 17fbe6cc] System.Threading.Monitor.Enter(System.Object)
17fbe720 00638427 MyProg.MyParentClass.ClockTimeElapsed(System.DateTime)
17fbe798 00637cf6 MyProg.MyEngine.ClockTimeElapsed(System.Object)
17fbe830 71df843f System.Threading._TimerCallback.TimerCallback_Context(System.Object)
17fbe838 71e302ff System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
17fbe850 71df83ab System.Threading._TimerCallback.PerformTimerCallback(System.Object)
17fbe9dc 74071b4c [GCFrame: 17fbe9dc]
0:000> ~45e!dso
OS Thread Id: 0xbcc (45)
ESP/REG Object Name
17fbe5a8 022a2ff4 System.Globalization.DaylightTime
17fbe5ac 022a2f3c System.Int32
17fbe5c8 02537b88 MyProg.MyChildClass
17fbe738 02537b88 MyProg.MyChildClass
17fbe740 02537b88 MyProg.MyChildClass
17fbe7ac 11572f28 System.Collections.ArrayList+ArrayListEnumeratorSimple
17fbe7b0 022f3490 System.Collections.ArrayList
17fbe7b4 0231860c System.String Error loading MyConfig.txt
17fbe7c0 022f3014 MyProg.MyEngine
17fbe84c 0231b48c System.Threading._TimerCallback
17fbe9fc 0231b48c System.Threading._TimerCallback
0:000> ~290e !clrstack
OS Thread Id: 0x1af8 (290)
ESP EIP
2e77f39c 77d2013d [HelperMethodFrame_1OBJ: 2e77f39c] System.Threading.ReaderWriterLock.AcquireReaderLockInternal(Int32)
2e77f3f8 0c3630d4 MyProg.MyEngine.GetBuyValue()
2e77f424 076fd4ad MyProg.MyParentClass.Execute(System.Object)
2e77f474 71e19fcf System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(System.Object)
2e77f47c 71e302ff System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
2e77f494 71e1a533 System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(System.Threading._ThreadPoolWaitCallback)
2e77f4a8 71e1a3c9 System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(System.Object)
2e77f638 74071b4c [GCFrame: 2e77f638]
0:000> ~290e!dso
OS Thread Id: 0x1af8 (290)
ESP/REG Object Name
2e77f35c 022f3014 MyProg.MyEngine
2e77f360 02369b98 System.Threading.ContextCallback
2e77f378 02369b98 System.Threading.ContextCallback
2e77f3dc 023188f8 System.Threading.ReaderWriterLock
2e77f400 024862d8 MyProg.MyChildClass
2e77f410 02369b98 System.Threading.ContextCallback
2e77f430 024862d8 MyProg.MyChildClass
2e77f43c 024862d8 MyProg.MyChildClass
2e77f460 02369b98 System.Threading.ContextCallback
2e77f490 1156dd74 System.Threading._ThreadPoolWaitCallback