On Windows when FileStream is opened for overlapped I/O, its BeginRead/Write methods would use overlapped I/O. Now in .NET 6 when no buffering is used, this is no longer the case: BeginRead/Write aren't overridden on the Windows strategy, and these operations end up using the base Stream implementation that queues work items (which will in turn block waiting on async I/O).
cc: @adamsitnik
On Windows when FileStream is opened for overlapped I/O, its BeginRead/Write methods would use overlapped I/O. Now in .NET 6 when no buffering is used, this is no longer the case: BeginRead/Write aren't overridden on the Windows strategy, and these operations end up using the base Stream implementation that queues work items (which will in turn block waiting on async I/O).
cc: @adamsitnik