Re: PostgreSQL 15.5 stops processing user queries

Andrey Zhidenkov <pensnarik(at)gmail(dot)com> writes:
> We have encountered an issue with our PostgreSQL 15.5 installation. The
> problem is that
> PostgreSQL server periodically falls into a state when it accepts new
> connections but
> doesn't execute any queries. The session which runs a query hangs and
> cannot be terminated
> via SIGINT (even if it's just "SELECT 1") - a corresponding linux process
> has state "S" and it's
> not terminated even if the PostgreSQL master process is stopped. No matter
> how we connect to
> the database - both TCP and unix socket sessions hang but it seems that
> existing sessions can
> still execute queries (once we succeeded to connect using pgBouncer which
> seemed to use an
> existing connection to the database).

Try using an existing session to capture pg_stat_activity and pg_locks
information about the stuck session(s).

> Here is a stack trace from gdb for one of the frozen sessions:

This appears to be a trace of a psql process waiting for a query
result. It won't teach you much about what the server is doing.

regards, tom lane