On Mon, 2025-09-01 at 03:52 +0000, Murthy Nunna wrote: > Pg16.10 > > I have a query which runs fine most of the time. When it runs fine, it spawns > parallel workers. In pg_stat_activity, wait_event is blank, state is active and > backend_type = "client backend" for the main query. For parallel workers of > this query I see wait_event = MessageQueueSend, state is active and > backend_type = "parallel worker" > > But some times, it has no parallel workers. wait_event is blank, state is active > and backend_type =client backend. And it never ends. It takes up lot of CPU. > The socket on both server and client server are in ESTABLISHED state > (netstat -tulpa | grep <client_port>). Perhaps no workers are spawned because "max_parallel_workers" has already been exhausted by other backends. Check for the number of concurrent parallel workers next time you get the error. I cannot know the source of your performance problems, but perhaps it is a combination of system overload and lack of available parallel worker processes, which might well go together. Yours, Laurenz Albe
