This question already has an answer here:
So we had some slow performance with timeouts this morning. When looking for the cause, our blocking query (uses DMVs) showed up as the blocking query. I think this was just a fluke but the job we use to get the blocking details was running 4 to 5 times slower than normal. I believe this is just a side effect of whatever was causing the timeouts.
So my question is whether querying the DMVs could actually cause blocking for queries on other tables? Doesn't seem logical.
dm_exec_sql_text dm_os_waiting_tasks dm_tran_locks dm_exec_sessions dm_exec_requests