Thread Management - Microsoft SQL Server 2008 Analysis Services - page 522

While building indexes, Analysis Services faces challenges similar to query execution and
uses a similar approach. The value of the Analysis Services CoordinatorBuildMaxThreads
property defines the number of segments that are indexed in parallel.
During the processing operation, Analysis Services also uses the
CoordinatorExecutionMode property to limit the number of partitions processed in paral-
lel. As mentioned in Chapter 21, “Dimension and Partition Processing,” Analysis Services
uses three threads for the processing of a single partition. When processing a large number
of partitions on the eight-processor machine, Analysis Services might create 8 * 4 * 3
threads, but the Concurrency value comes into play here again and limits number of
active threads.