Thread: Backend process is still runs even postmaster got killed
Backend processes are still running even if the postmaster got killed and all other server processes are exited by checking the
Postmaster status.
And the backend process is providing the service to the client.
Is there any problems are possible? If we continue the system for a long time with the above behavior?
Until all these kind of backend processes are exited, postmaster is failing to start.
Manual cleanup is required for these backend processes? Or is there anyway we can handle?
Regards,
Hari babu.
Backend processes are still running even if the postmaster got killed and all other server processes are exited by checking the
Postmaster status.
And the backend process is providing the service to the client.
Is there any problems are possible? If we continue the system for a long time with the above behavior?
Until all these kind of backend processes are exited, postmaster is failing to start.
Manual cleanup is required for these backend processes? Or is there anyway we can handle?
Regards,
Hari babu.
Hi Hari.
-m SHUTDOWN-MODE can be "smart", "fast", or "immediate"
Shutdown modes are:
smart quit after all clients have disconnected
fast quit directly, with proper shutdown
immediate quit without complete shutdown; will lead to recovery on restart
"Smart" will wait for all your backend processes to terminate (or fail if it takes too long). If i remember correctly "fast" will cause the postmaster to exit even if backends are still up, the equivalent of sending a kill -15 (SIGTERM). And "immediate" is like sending a kill -9 (SIGKILL) i.e. violent shutdown of everything.
I'm guessing you went for the equivalent of SIGTERM that's why you still have backends running.
regards,
--thalis
>On Fri, Dec 7, 2012 at 7:26 PM, Thalis Kalfigkopoulos <tkalfigo(at)gmail(dot)com> wrote:
>>On Fri, Dec 7, 2012 at 10:21 AM, Hari Babu <haribabu(dot)komm(at)huawei(dot)com> wrote:
>>Backend processes are still running even if the postmaster got killed and all other server processes are exited by checking the
>>Postmaster status.
>>And the backend process is providing the service to the client.
>>Is there any problems are possible? If we continue the system for a long time with the above behavior?
>>Until all these kind of backend processes are exited, postmaster is failing to start.
>>Manual cleanup is required for these backend processes? Or is there anyway we can handle?
>Hi Hari.
>
>How exactly do you kill the postmaster? It is suggested you use pg_ctl for server shutdowns/restarts. Check out the option -m:
>-m SHUTDOWN-MODE can be "smart", "fast", or "immediate"
>Shutdown modes are:
> smart quit after all clients have disconnected
> fast quit directly, with proper shutdown
> immediate quit without complete shutdown; will lead to recovery on restart
>"Smart" will wait for all your backend processes to terminate (or fail if it takes too long). If i remember correctly "fast" will cause the postmaster to exit even if >backends are still up, the equivalent of sending a kill -15 (SIGTERM). And "immediate" is like sending a kill -9 (SIGKILL) i.e. violent shutdown of everything.
>
>I'm guessing you went for the equivalent of SIGTERM that's why you still have backends running.
Usually we are using the pg_ctl with shutdown option only.
Actually I thought of asking the postmaster crash scenario, which I have simulated with kill -9 PID.
I know postmaster crash is a very rare scenario, In this I want to know what are all the problems can occur?
Regards,
Hari babu.
Hari Babu wrote: > Backend processes are still running even if the postmaster got killed and > all other server processes are exited by checking the > > Postmaster status. What server version? -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
On Fri, Dec 7, 2012 at 10:21 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote: >>Hari Babu wrote: >> Backend processes are still running even if the postmaster got killed and >> all other server processes are exited by checking the >> >> Postmaster status. >What server version? I had tested it in 9.3 devel and 9.2 as well. I tested as follows. ./pg_ctl -D data start ./psql postgres In another terminal kill the postmaster with kill -9 PID. Now start using the psql which is already connected, it can execute all queries. And check the server processes (ps -elf | grep postgres) only backend process will remain. I know postmaster crash is a very rare scenario, If backend continuously providing the service, I want to know what are all the problems can occur? Regards, Hari babu.