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Thread: Lock timeout in commit

Lock timeout in commit

From
Steve Baldwin
Date:
Hi all,

I'm occasionally seeing a lock timeout in a commit statement. For example:

2025-07-10 08:56:07.225 UTC,"b2bc_api","b2bcreditonline",23592,"10.124.230.241:60648",686f8022.5c28,55,"COMMIT",2025-07-10 08:56:02 UTC,3984/10729,676737574,ERROR,55P03,"canceling statement due to lock timeout",,,,,,"COMMIT",,,"098c62f7-bb76-4607-88da-120c6edee423","client backend",,-2835399305386018931

Am I right in thinking this is likely due to a deferred foreign key constraint? I couldn't see any obvious clue in the log. Is there somewhere else I can look?

In case it matters, the server is running version 17.4.

Thanks,

Steve

Re: Lock timeout in commit

From
Tom Lane
Date:
Steve Baldwin <steve.baldwin@gmail.com> writes:
> I'm occasionally seeing a lock timeout in a commit statement. For example:

> 2025-07-10 08:56:07.225 UTC,"b2bc_api","b2bcreditonline",23592,"
> 10.124.230.241:60648",686f8022.5c28,55,"COMMIT",2025-07-10 08:56:02
> UTC,3984/10729,676737574,ERROR,55P03,"canceling statement due to lock
> timeout",,,,,,"COMMIT",,,"098c62f7-bb76-4607-88da-120c6edee423","client
> backend",,-2835399305386018931

> Am I right in thinking this is likely due to a deferred foreign key
> constraint?

Plausible guess perhaps, although FKs don't normally need strong
locks.

> I couldn't see any obvious clue in the log. Is there somewhere
> else I can look?

I think all you could do is monitor the pg_locks view and hope to
catch the process in "waiting" state before it fails.

It occurs to me to wonder though if we couldn't provide more
context in the error about what lock is being waited for.

            regards, tom lane

Re: Lock timeout in commit

From
Steve Baldwin
Date:
On Fri, 11 Jul 2025 at 01:28, Tom Lane <tgl@sss.pgh.pa.us> wrote:

I think all you could do is monitor the pg_locks view and hope to
catch the process in "waiting" state before it fails.

It occurs to me to wonder though if we couldn't provide more
context in the error about what lock is being waited for.

Thanks Tom !!

The application is an API server so we intentionally set the lock timeout to a very short interval (5 ms). Having locking context would be great.

Other than deferred FK constraints, what other locking actions are deferred to commit time?

Cheers,

Steve