Horton

Re: Logical replication timeout problem

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>
Cc: Fabrice Chapuis <fabrice636861@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-01-20T13:18:14Z
Lists: pgsql-hackers 
On Thu, Jan 20, 2022 at 2:35 PM wangw.fnst@fujitsu.com
<wangw.fnst@fujitsu.com> wrote:
>
> On Wed, Jan 19, 2022 at 9:53 PM Fabrice Chapuis fabrice636861@gmail.com wrote:
>
> > Hello Amit,
>
> > If it takes little work for you, can you please send me a piece of code
>
> > with the change needed to do the test
>
>
>
> I wrote a patch(Send-keepalive.patch, please refer to attachment) according to
>
> Amit's suggestions. But after I did some simple test about this patch by the
>
> test script "test.sh"(please refer to attachment), I found the timeout problem
>
> has not been fixed by this patch.
>
>
>
> So I add some logs(please refer to Add-some-logs-to-debug.patch) to confirm newly
>
> added WalSndKeepaliveIfNecessary() send keepalive message or not.
>
>
>
> After applying the Send-keepalive.patch and Add-some-logs-to-debug.patch, I
>
> found that the added message "send keep alive message" was not printed in
>
> publisher-side log.
>

It might be not reaching the actual send_keep_alive logic in
WalSndKeepaliveIfNecessary because of below code:
{
...
/*
* Don't send keepalive messages if timeouts are globally disabled or
* we're doing something not partaking in timeouts.
*/
if (wal_sender_timeout <= 0 || last_reply_timestamp <= 0)
return;
..
}

I think you can add elog before the above return and before updating
progress in the below code:
case REORDER_BUFFER_CHANGE_INSERT:
  if (!relentry->pubactions.pubinsert)
+ {
+ OutputPluginUpdateProgress(ctx);
  return;

This will help us to rule out one possibility.

-- 
With Regards,
Amit Kapila.

Commits

  1. Fix the logical replication timeout during large DDLs.

  2. Fix the logical replication timeout during large transactions.

  3. Rethink the delay-checkpoint-end mechanism in the back-branches.

  4. Revert "Logical decoding of sequences"

  5. Skip empty transactions for logical replication.

  6. Allow specifying column lists for logical replication

  7. Add decoding of sequences to built-in replication

  8. Fix ABI break introduced by commit 4daa140a2f.

  9. Lag tracking for logical replication