2004765 - AccessViolationException periodically encountered in AseConnection.Close on a multi-threaded IIS application - SDK for SAP ASE

AccessViolationException periodically encountered in AseConnection.Close on a multi-threaded  IIS application  after connection to ASE times out.

Using the blocked remote i/o method to induce the timeout. That's where the middle tier calls a proc that does a select on a proxy table that has been locked on the remote server in exclusive mode.
Here's the sequence of events:

• Presentation tier to middle tier timeout is 3:15. Middle tier to db tier timeout is 3:00
  0:00 middle tier calls proc that reads locked proxy table. DB spid is in remote i/o state, proxied to user account (as expected)
  3:15 presentation tier records timeout message
  6:02 driver returns error 30046 - "Connection to Sybase server has been lost. Connection died from command timeout. All active transactions have been rolled back." DB spid is still in remote i/o state, proxied to user account . It's interesting to note that error 30046 occurs at about 2x the database timeout. Other tests have shown the same timing.
  11:00 lock on remote table is released. DB spid is in recv sleep state, still proxied to user account (expected, since set proxy to MT account could not be executed)
  12:46 MT crashes. Message in ASE log: Cannot read, host process disconnected
  
  << windows application event log, >>
  
  Windows message:
  Application: Service.exe
  Framework Version: v4.0.30319
  Description: The process was terminated due to an unhandled exception.
  Exception Info: System.AccessViolationException
  Stack:
  at Sybase.Data.AseClient.Unmanaged.CloseConnection(IntPtr)
  at Sybase.Data.AseClient.AseConnectionImpl.Close()
  at Sybase.Data.AseClient.AseConnectionImpl.Finalize()
  
  Faulting application name: Service.exe, version: 1.0.0.0, time stamp: 0x524d07f3
  Faulting module name: unknown, version: 0.0.0.0, time stamp: 0x00000000
  Exception code: 0xc0000005
  Fault offset: 0x206e6f69
  Faulting process id: 0x7d4
  Faulting application start time: 0x01cebffdfb88d4a3
  Faulting application path: Service.exe
  Faulting module path: unknown
  Report Id: e99cd51a-2c30-11e3-949c-8631cddad159
  
  << nothing recorded in system event log >
• In a previous test with timing similar to the above, the MT crashed with the message:
  << windows system event log >>
  Application popup: Microsoft Visual C++ Runtime Library : Runtime Error!
  
  Program: C:\Service.exe
  
  R6025
  - pure virtual function call
  
  << windows application event log >>
  
  Faulting application name: Service.exe, version: 1.0.0.0, time stamp: 0x524bb681
  Faulting module name: sybdrvado20.dll, version: 2.157.1101.0, time stamp: 0x52427071
  Exception code: 0x40000015
  Fault offset: 0x0006cb89
  Faulting process id: 0x2f94
  Faulting application start time: 0x01cebf3536dc2835
  Faulting application path: WCFService.exe
  Faulting module path: C:\Windows\TEMP\Sybase.AdoNet4.AseClient.32bits.4.157.1101.0\sybdrvado20.dll
  Report Id: a1e0f285-2b61-11e3-b5ad-663a32047475
  
  

• SAP Sybase Software Developer Kit (SDK) 15.7 SP110
• Adaptive Server Enterprise ADO.NET Data Provider
• 4.0 Provider ( Sybase.AdoNet4.AseClient.dll )
• .net 4

KBA , BC-SYB-SDK , SDK , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem