STG_E_LOCKVIOLATION from StgOpenStorage when reading a network file from multiple servers

We have found that if processes on multiple machines attempt to open a networked structured storage file forreading they will occasionally report ‘A lock violation has occurred’ (STG_E_LOCKVIOLATION). 

FYI: We use the flags according tohttp://msdn.microsoft.com/en-us/library/aa380341(v=vs.85).aspx to ensure we only deny writers on reading the file. 

I have created a very simple C# test app and can reliably reproduce the error.

The API under test is simply:

    private static void PerformTheTest(string filename)
    {
      NativeMethods.IStorage stgOpen;
      // Use interop to open the structured storage file.
      // According to http://msdn.microsoft.com/en-us/library/aa380341(v=vs.85).aspx:
      //
      //  To support the single-writer, multireader, direct mode, the first flag combination is the valid grfMode parameter for the writer. The second flag combination is valid for readers.
      //    STGM_DIRECT_SWMR | STGM_READWRITE | STGM_SHARE_DENY_WRITE
      //    STGM_DIRECT_SWMR | STGM_READ | STGM_SHARE_DENY_NONE
      //
      //  In direct mode, one of the following three combinations are valid.
      //    STGM_DIRECT | STGM_READWRITE | STGM_SHARE_EXCLUSIVE
      //    STGM_DIRECT | STGM_READ | STGM_SHARE_DENY_WRITE
      //    STGM_DIRECT | STGM_READ | STGM_SHARE_EXCLUSIVE
      var errorCode = NativeMethods.StgOpenStorage(filename,
        null,
        NativeMethods.STGM.DIRECT | NativeMethods.STGM.SHARE_DENY_WRITE | NativeMethods.STGM.READ,
        IntPtr.Zero,
        0,
        out stgOpen);
      if (errorCode != 0) Marshal.ThrowExceptionForHR(errorCode);
      // Release the storage.
      // NOTE: If we don't do this we run out of memory
      // e.g. There is insufficient memory available to complete operation. (Exception from HRESULT: 0x80030008 (STG_E_INSUFFICIENTMEMORY))
      Marshal.ReleaseComObject(stgOpen);
    }

This has been tested in a Windows Server 2008 R2 environment and can be reproduced within minutes – often within seconds – using just three machines.

Regards

Andy