Re: Backend process is still runs even postmaster got killed

[Hari Babu <haribabu.kommi@xxxxxxxxxx>]

>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.