Re: [HACKERS] Interval for launching the table sync worker

On Thu, Apr 6, 2017 at 9:06 PM, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> At Thu, 06 Apr 2017 17:02:14 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote
in<20170406.170214.263553093.horiguchi.kyotaro@lab.ntt.co.jp>
 
>> At Thu, 6 Apr 2017 16:15:33 +0900, Masahiko Sawada <sawada.mshk@gmail.com> wrote in
<CAD21AoCrcwi3SwKKOW_efwW0finxyycLgsbw09n5uy2sxneO_A@mail.gmail.com>
>> > On Thu, Apr 6, 2017 at 3:45 PM, Kyotaro HORIGUCHI
>> > <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
>> > > I was thinking the same.
>> > >
>> > > At Thu, 6 Apr 2017 11:33:22 +0900, Masahiko Sawada <sawada.mshk@gmail.com> wrote in
<CAD21AoDCnyRJDUY=ESVVe68AukvOP2dFomTeBFpAd1TiFbjsGg@mail.gmail.com>
>> > >> Hi all,
>> > >>
>> > >> While testing table sync worker for logical replication I noticed that
>> > >> if the table sync worker of logical replication failed to insert the
>> > >> data for whatever reason, the table sync worker process exits with
>> > >> error. And then the main apply worker launches the table sync worker
>> > >> again soon without interval. This routine is executed at very high
>> > >> frequency without interval.
>> > >>
>> > >> Should we do put a interval (wal_retrieve_interval or make a new GUC
>> > >> parameter?) for launching the table sync worker?
>
> Hmm. I was playing with something wrong. Now I see the invervals
> 5 seconds. No problem.

Yeah, this issue happens only in the table sync worker.

>
>> > > After introducing encoding conversion, untranslatable characters
>> > > in a published table causes this situation.
>> >
>> > I think it's better to make a new GUC parameter for the table sync
>> > worker. Having multiple behaviors in wal_retrieve_retry_interval is
>> > not good idea. Thought?
>
> So, this is working, sorry.
>
>> I prefer subscription option than GUC. Something like following.
>>
>> CREATE SUBSCRIPTION s1 CONNECTION 'blah'
>>        PUBLICATION p1 WITH (noreconnect = true);
>>
>> Stored in pg_subscription?
>>
>> > > Interval can reduce
>> > > the frequence of reconnecting, but I think that walreciever
>> > > should refrain from reconnecting on unrecoverable(or repeating)
>> > > error in walsender.
>> > >
>> >
>> > Yeah, that's also considerable issue.
>>
>> But not to do now.
>

I've added this as an open item, and sent a patch for this.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center