apache/log4net — pull request #3 by cosminonea (2012-10-04 16:47:52+00:00)
Title: using ReaderWriterLockSlim when compiling for .net 4 for improved perfor...

ReaderWriterLockSlim is supposed to improve the lock contention/context switches in a busy application with loads of logging.

http://msdn.microsoft.com/en-us/library/system.threading.readerwriterlockslim.aspx