Re: Dangling Client Backend Process

On Fri, Oct 16, 2015 at 3:34 PM, Rajeev rastogi <rajeev(dot)rastogi(at)huawei(dot)com>
wrote:
>
>
> Yes it will be really helpful to know the earlier reason for "not making
> backend exit on postmaster death".
> Please let me know if there is any thread, which I can refer to find the
> same.
>
> IMHO there could be below major issues, if we don't kill client backend
> process on postmaster death:
> 1. Postmaster cannot be re-started again as pointed by Kyotaro and Andres
> Also.
> 2. If from existing client session, we try to do some operation which has
> dependency with backend process, then that operation will either fail or
> may lead to undefined behavior sometime.
> 3. Also unintentionally all operation done by application will not be
> checkpointed and also will not be flushed by bgworker.
> 4. Replicating of WAL to standby will be stopped and if synchronous
> standby is configured then command from master will be hanged.
>
>
What exactly we want to do as part of this proposal? As far as I
can see, we have below two options on postmaster death:

a. Exit all the active backends in whichever state they are.
b. Exit backend/s after they finish there current work and are
waiting for new command.

I think what we are discussing here is option-b.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com