问题
I have a strange problem. A process gets frozen/stuck while reading data using System.Data.SqlClient.SqlDataReader on GetValue() function. I am analyzing the process dump using WinDbg. I used SOS commands like !dlk, !SyncBlk, !analyze -v -hang etc. but none of them indicate any deadlocks.
The last call on callstack is
000000001a98e8a8 0000000076febd7a [InlinedCallFrame: 000000001a98e8a8] .**SNIReadSyncOverAsync**(SNI_ConnWrapper*, SNI_Packet**, Int32)
000000001a98e8a8 000007fee9e8bca1 [InlinedCallFrame: 000000001a98e8a8] .SNIReadSyncOverAsync(SNI_ConnWrapper*, SNI_Packet**, Int32)
000000001a98e880 000007fee9e8bca1 DomainBoundILStubClass.IL_STUB_PInvoke(SNI_ConnWrapper*, SNI_Packet**, Int32)
000000001a98e950 000007fee9e7254f SNINativeMethodWrapper.SNIReadSyncOverAsync(System.Runtime.InteropServices.SafeHandle, IntPtr ByRef, Int32)
000000001a98e9c0 000007fee9e7226e System.Data.SqlClient.TdsParserStateObject.ReadSniSyncOverAsync()
000000001a98ea70 000007fee9e72180 System.Data.SqlClient.TdsParserStateObject.TryReadNetworkPacket()
000000001a98eab0 000007fee9e72950 System.Data.SqlClient.TdsParserStateObject.TryPrepareBuffer()
000000001a98eae0 000007fee9e728d8 System.Data.SqlClient.TdsParserStateObject.TryReadByteArray(Byte[], Int32, Int32, Int32 ByRef)
000000001a98eb50 000007feea4c0adc System.Data.SqlClient.TdsParser.TryReadSqlValue(System.Data.SqlClient.SqlBuffer, System.Data.SqlClient.SqlMetaDataPriv, Int32, System.Data.SqlClient.TdsParserStateObject)
000000001a98ec10 000007fee9e85cb5 System.Data.SqlClient.SqlDataReader.TryReadColumnInternal(Int32, Boolean)
000000001a98ecb0 000007fee9e85af0 System.Data.SqlClient.SqlDataReader.TryReadColumn(Int32, Boolean, Boolean)
000000001a98ed20 000007fee9e85a0b System.Data.SqlClient.SqlDataReader.GetValueInternal(Int32)
000000001a98ed60 000007fee9e859b7 System.Data.SqlClient.SqlDataReader.GetValue(Int32)
What are other avenues for further debugging here? Did someone face the same issue with SqlDataReader?
I recently found out when this kind of stack trace is found, there is always a Win32 error in dump like this.
0:009> !gle LastErrorValue: (Win32) 0x3e5 (997) - Overlapped I/O operation is in progress. LastStatusValue: (NTSTATUS) 0xc0000034 - Object Name not found.
Does this mean it is blocked due to some underlying IO operation?
来源：https://stackoverflow.com/questions/43907029/windbg-process-frozen-on-snireadsyncoverasync-but-no-deadlock-found