BROKER_ENDPOINT_STATE_MUTEX

Occurs when there is contention to access the state of a Service Broker connection endpoint. Access to the state for changes is serialized. Information from Microsoft®

This wait type is charged each time there is some state change for a Service Broker (or Database Mirroring) connection endpoint during the connection establishment (i.e. handshake) phase - e.g. initialization before connect or after accept, login negotiation (authentication, encryption), validation, error, arbitration and error. This wait type is also charged per connection endpoint every time sys.dm_broker_connections (or sys.dm_db_mirroring_connections) DMV is queried to serialize access to each connections handshake state.

Avg_wait_time_ms for this wait type should be very small and the wait_time_ms and waiting_tasks_count should both be proportional to the number of times Service Broker (or Database Mirroring) establishes connection with some other SQL server instance and the number of times sys.dm_broker_connections (or sys.dm_db_mirroring_connections) DMV is queried.

Rapidly increasing values of wait_time_ms and waiting_tasks_count for this DMV could indicate very frequent connection establishment (and teardown). Since service broker transport tears down connections after ~90 seconds of inactivity, these values can increase if applications use service broker once every ~90 seconds. Source: http://blogs.msdn.com/b/sql_service_broker/archive/2008/12/01/service-broker-wait-types.aspx