Re: [RFC] Should we fix postmaster to avoid slow shutdown?

On Wed, Sep 28, 2016 at 8:37 AM, Tsunakawa, Takayuki
<tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> wrote:
>> From: pgsql-hackers-owner(at)postgresql(dot)org
>> [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Tom Lane
>> Allowing SIGQUIT to prompt fast shutdown of the stats collector seems sane,
>> though. Try to make sure it doesn't leave partly-written stats files
>> behind.
>
> The attached patch based on HEAD does this. I'd like this to be back-patched because one of our important customers uses 9.2.
>
> I didn't remove partially written stat files on SIGQUIT for the following reasons. Is this OK?
>
> 1. The recovery at the next restart will remove the stat files.
> 2. SIGQUIT processing should be as fast as possible.
> 3. If writing stats files took long due to the OS page cache flushing, removing files might be forced to wait likewise.
>

I agree with the first point.

The patch applies and compiles clean. make check-world is clean.

In pgstat_quickdie(), I think a call to sigaddset(&BlockSig, SIGQUIT) is
missing before PG_SETMASK(). Although there are some SIGQUIT handlers which do
not have that call. But I guess, it will be safer to have it.

Also, many other SIGQUIT handlers like bgworker_quickdie() call on_exit_reset()
followed by exit(2) instead of just exit(1) in pgstat_quickdie(). Why is this
difference?

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company