How to diagnose a process in PostreSQL?

Question

PostgreSQL

The situation is this, there is a request to the database which hangs tightly in production.
In this case, the client also freezes. Since the server stops responding to him.
I have to kill the request so that the client can continue working with:
select pg_terminate_backend(ид-процесса);
I see that this request is hanging by the process with:

SELECT * FROM pg_stat_activity where state = 'active' order by query_start asc;

The problem is that locally, this problem cannot be reproduced.
Dear Developers, help advice please.
Are there any tools for debugging and profiling such problems?

Answer 1

The problem was solved by reloading postgres and executing the VACUUM command. Thank you all for your participation.