Trace Analysis Patterns (Part 24)

The limit of Discontinuity pattern is No Activity. The absence of activity can be seen at a thread level or at a process level where it is similar to Missing Component pattern. The difference from the latter pattern is that we know for certain that we selected our process modules for tracing but don’t see any trace messages. Consider this example:

#  Source        PID  TID  Time         Function     Message
1  TraceSettings 1480 8692 08:04:20.682              **** Start Trace Session 
[... TraceSettings messages 2-11 show that we selected AppA for tracing ...]
12 ModuleB       3124 4816 08:04:37.049 WorkerThread Worker thread running
13 TraceSettings 1480 8692 08:04:41.966              **** Trace Session was stopped

Only modules from AppA process and modules from a coupled process (for example, ModuleB) were selected. However, we only see a reminder message from the coupled process (3124.4816:ModuleB!WorkerThread) and no messages for 21 seconds. Fortunately, AppA process memory dump was saved during the tracing session:

Debug session time: Fri May 21 08:04:31.000 2010 (GMT+0)

We see 2 threads waiting for a critical section:

0:000> ~*kL

  14  Id: 640.8b8 Suspend: 1 Teb: 7ffa7000 Unfrozen
ChildEBP RetAddr 
0248f8c0 7c827d29 ntdll!KiFastSystemCallRet
0248f8c4 7c83d266 ntdll!ZwWaitForSingleObject+0xc
0248f900 7c83d2b1 ntdll!RtlpWaitOnCriticalSection+0x1a3
0248f920 0040dea8 ntdll!RtlEnterCriticalSection+0xa8
0248f9a4 77ce78aa rpcrt4!Invoke+0×30
0248f9c0 77ce7a94 rpcrt4!NdrCallServerManager+0×17
0248fcb8 77ce7b7c rpcrt4!NdrStubCall+0×1d6
0248fcd0 77c7ff7a rpcrt4!NdrServerCall+0×15
0248fd04 77c8042d rpcrt4!DispatchToStubInCNoAvrf+0×38
0248fd58 77c80353 rpcrt4!RPC_INTERFACE::DispatchToStubWorker+0×11f
0248fd7c 77c7e0d4 rpcrt4!RPC_INTERFACE::DispatchToStub+0xa3
0248fdbc 77c7e080 rpcrt4!RPC_INTERFACE::DispatchToStubWithObject+0xc0
0248fdfc 77c812f0 rpcrt4!LRPC_SCALL::DealWithRequestMessage+0×41e
0248fe20 77c88678 rpcrt4!LRPC_ADDRESS::DealWithLRPCRequest+0×127
0248ff84 77c88792 rpcrt4!LRPC_ADDRESS::ReceiveLotsaCalls+0×430
0248ff8c 77c8872d rpcrt4!RecvLotsaCallsWrapper+0xd
0248ffac 77c7b110 rpcrt4!BaseCachedThreadRoutine+0×9d

  15  Id: 640.18c0 Suspend: 1 Teb: 7ffdb000 Unfrozen
ChildEBP RetAddr 
01b8ff40 7c827d29 ntdll!KiFastSystemCallRet
01b8ff44 7c83d266 ntdll!ZwWaitForSingleObject+0xc
01b8ff80 7c83d2b1 ntdll!RtlpWaitOnCriticalSection+0x1a3
01b8ffa0 0040dba7 ntdll!RtlEnterCriticalSection+0xa8
01b8ffec 00000000 kernel32!BaseThreadStart+0×34

Unfortunately it belongs to a missing thread and blocked threads wait forever:

0:000> !cs -l -o -s
DebugInfo          = 0x01facdd0
Critical section   = 0x01da19c0 (+0x1DA19C0)
LockCount          = 0×2
WaiterWoken        = No
OwningThread       = 0×00001384
RecursionCount     = 0×1
LockSemaphore      = 0×578
SpinCount          = 0×00000000
ntdll!RtlpStackTraceDataBase is NULL. Probably the stack traces are not enabled

0:000> ~~[1384]
              ^ Illegal thread error in ‘~~[1384]’

Apparently AppA process was hanging and it explains why we don’t see any activity in the trace. We suggested to enable user mode stack trace database using this article as an example: CTX106970 and get a new dump.

- Dmitry Vostokov @ + -

One Response to “Trace Analysis Patterns (Part 24)”

  1. Dmitry Vostokov Says:

    A good example:

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