Call BeginRead before reading from the memory protected by the multi-read exclusive-write synchronizer. BeginRead does not return until there are no other threads writing to the memory. After calling BeginRead, other threads can be granted read access to the protected memory by the BeginRead method. However, any thread asking for write permission by calling BeginWrite must wait until all reading threads have called EndRead. 

EndRead 

BeginWrite 

Using the Multi-read Exclusive-write Synchronizer