SQL Server parallelism issue
Suspended status doesn't tell you much; the wait type tells you the story. I would;


Download and Install sp_whoIsActive execute the below command while the processes are suspended to get the leading blocker, it's wait type along the lock graph. This should show the lock areas. (please upload)



exec sp_WhoIsActive 
  @show_own_spid=1, 
  @show_sleeping_spids=1, 
  @get_task_info =2, 
  @get_locks=1, 
  @get_additional_info=1, 
  @find_block_leaders=1,
  @format_output = 0




Setup a SQL blocking report trace. Here is the link with scripts to set up the blocked report SQL trace. Set the blocked process threshold to 20 secs or higher


Please upload these results for review