The JDBC driver usually sets the implicit transaction on in every query executed by the client.
I found many SELECT statements in suspended state with implicit transaction set to ON using Version Store for 48 hour.
These selects statements didn't take up much tempdb space, but I was wondering if this might have blocked version cleanup even though the UPDATE / DELETE / INSERT statements that generated the version store rows had already been committed. (many databases use read committed snapshot isolation level)
After I killed the sessions the version store space became free.
I found the select statement using the version store with the following query:
SELECT db_name(spu.database_id) as database_name, ast.session_id, ast.transaction_id, ast.transaction_sequence_num, ast.elapsed_time_seconds, b.program_name, b.open_tran, b.status, ses.row_count, (spu.user_objects_alloc_page_count * 8) AS user_objects_kb, (spu.user_objects_dealloc_page_count * 8) AS user_objects_deallocated_kb, (spu.internal_objects_alloc_page_count * 8) AS internal_objects_kb, (spu.internal_objects_dealloc_page_count * 8) AS internal_objects_deallocated_kb, loginame, last_request_start_time, last_request_end_time, cmd, lastwaittype FROM sys.dm_tran_active_snapshot_database_transactions ast JOIN sys.dm_exec_sessions ses ON ses.session_id = ast.session_id JOIN sys.dm_db_session_space_usage spu ON spu.session_id = ses.session_id JOIN sys.sysprocesses b on ast.session_id = b.spid ORDER BY elapsed_time_seconds DESC