postgres disconnects on master after setting up replication

Andy Hall <andyjohnhall@gmail.com> writes:

we have an odd issue where a java app using JDBC which has been
working fine has suddenly started disconnecting after we setup
replication from the database it was connecting to ( which is now the
primary in a replicating pair ) with errors such as the following...

CLIENT SIDE: DBNAME/logs/20210815-200601.20966.log:SessionManagerImpl
WARN 20210816-00:01:00.252 - A session lost connection with the
database. Disabling all sessions
SERVER SIDE: 2021-08-16 01:48:27 BST FATAL: unsupported frontend
protocol 1234.5680: server supports 1.0 to 3.0

Hmm. That "protocol version" is a GSS request:

#define NEGOTIATE_GSS_CODE PG_PROTOCOL(1234,5680)

So

1. You are using a server version that predates our GSS support.

2. On the other hand, the client knows GSS and is trying to use it.
The client should fall back to a non-GSS connection upon receiving
this error response. But ...

3. Something --- it's not very clear what --- is seeing the error
and going into an unwarranted panic.

I'd try to figure out what's issuing the "Disabling all sessions"
message and then filing a complaint with the authors of that.

regards, tom lane

thanks for the very clear explanation much appreciated shall take this
back to the team.

Dave Cramer
www.postgres.rocks

On Mon, 16 Aug 2021 at 12:32, Andy Hall <andyjohnhall@gmail.com> wrote:

thanks for the very clear explanation much appreciated shall take this
back to the team.

On Mon, 16 Aug 2021 at 17:14, Tom Lane <tgl@sss.pgh.pa.us> wrote:

Andy Hall <andyjohnhall@gmail.com> writes:

we have an odd issue where a java app using JDBC which has been
working fine has suddenly started disconnecting after we setup
replication from the database it was connecting to ( which is now the
primary in a replicating pair ) with errors such as the following...

CLIENT SIDE: DBNAME/logs/20210815-200601.20966.log:SessionManagerImpl
WARN 20210816-00:01:00.252 - A session lost connection with the
database. Disabling all sessions
SERVER SIDE: 2021-08-16 01:48:27 BST FATAL: unsupported frontend
protocol 1234.5680: server supports 1.0 to 3.0

Hmm. That "protocol version" is a GSS request:

#define NEGOTIATE_GSS_CODE PG_PROTOCOL(1234,5680)

So

1. You are using a server version that predates our GSS support.

2. On the other hand, the client knows GSS and is trying to use it.
The client should fall back to a non-GSS connection upon receiving
this error response. But ...

3. Something --- it's not very clear what --- is seeing the error
and going into an unwarranted panic.

I'd try to figure out what's issuing the "Disabling all sessions"
message and then filing a complaint with the authors of that.

What version of the JDBC driver are you using? There was one version that
unfortunately blindly sent out the GSS request.
That has been rectified in later versions, I believe somewhere around
42.2.20 or so.

Although as Tom mentioned the driver does know how to deal with this,
however there are some cloud providers that chose to just drop the
connection

Dave

yep we think this is exactly the issue...we have been testing a new
build with a later driver in UAT this morning and no recurrence of the
issue so looking most probable. thanks all for the very prompt and
clear responses it's most appreciated.