If you query the sys.dm_db_task_space_usage dynamic management view (DMV) while this issue is occurring, you might see that the "internal_objects_dealloc_page_count" value does not increase at the same rate as "internal_objects_alloc_page_count" for session IDs that are running internal Service Broker tasks.
Additionally, the tempdb space is not released even after all pending conversations are closed and cleaned up.
Cumulative update informationCumulative Update 5 for SQL Server 2012 Service Pack 3 (SP3)
Cumulative Update 10 for SQL Server 2014 SP1
Cumulative update 3 for SQL Server 2014 SP2
To avoid this problem, follow the general recommendations in the "Performance and Scalability Techniques" section of the following TechNet topic:
Article ID: 3005011 - Last Review: Dec 28, 2016 - Revision: 1