Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer


Disables performance-critical locking in I/O operations.


Defining this symbol can improve performance in single-threaded I/O-bound programs by forcing all I/O operations to assume a single-threaded I/O model. For more information, see Multithreaded Libraries Performance.

© 2016 Microsoft