Re: How to kill a Background worker and Its metadata

On 28 June 2016 at 02:27, Akash Agrawal <aagrawa6@ncsu.edu> wrote:

Hi,

I've created a background worker and I am using Postgresql-9.4. This bgworker handles the job queue dynamically and goes to sleep if there is no job to process within the next 1 hour. 

Now, I want to have a mechanism to wake the bgworker up in case if someone adds a new job while the bgworker is in sleep mode. So to do it, I have created a trigger which initially removes the existing background worker and then registers a new one.

Don't do that.

Instead, set the background worker's process latch, which you can find in the PGPROC array. There are a variety of examples of how to set latches in the sources.

I am retrieving the pid from pg_Stat_activity. The maximum number of background worker that can run simultaneously is equal to 8.  I think even if I call pg_terminate_backend the metadata of the background worker is not being deleted

Correct. Unless you register it as a dynamic bgworker with no automatic restart, it'll get restarted when it exits uncleanly.

Have the worker call proc_exit(0) if you want it not to be restarted.

--

 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services