log4net SDK Documentation - Microsoft .NET Framework 4.0

ReaderWriterLock.AcquireWriterLock Method 

Acquires the writer lock

[Visual Basic]
Public Sub AcquireWriterLock()
[C#]
public void AcquireWriterLock();

Remarks

This method blocks if another thread has a reader lock or writer lock.

See Also

ReaderWriterLock Class | log4net.Util Namespace