[Performance counter] # of Sink Blocks in use [Description] 
Displays the current number of syncronization blocks in use. Synchronization blocks are per-object data structures allocated for storing synchronization information. Synchronization blocks hold weak references to managed objects and must be scanned by the garbage collector. Synchronization blocks are not limited to storing synchronization information; they can also store COM interop metadata. This counter indicates performance problems with heavy use of synchronization primitives.