Re: Stack overflow issue

From: Egor Chindyaskin <kyzevan23(at)mail(dot)ru>
To: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Sascha Kuhl <yogidabanli(at)gmail(dot)com>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Stack overflow issue
Date: 2023-12-21 08:45:47
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On 24/11/2023 21:14, Heikki Linnakangas wrote:
> What do you think?
Hello! Thank you for researching the problem! I'm more of a tester than
a developer, so I was able to check the patches from that side.
I've configured the server with CFLAGS=" -O0" and cassert enabled and
checked the following queries:

(n=1000000; printf "BEGIN;"; for ((i=1;i<=$n;i++)); do printf "SAVEPOINT
s$i;"; done; printf "ERROR; COMMIT;") | psql >/dev/null

(n=1000000; printf "BEGIN;"; for ((i=1;i<=$n;i++)); do printf "SAVEPOINT
s$i;"; done; printf "SET log_min_messages = 'DEBUG5'; SAVEPOINT sp;") |
psql >/dev/null

(n=1000000; printf "begin;"; for ((i=1;i<=$n;i++)); do printf "savepoint
s$i;"; done; printf "release s1;" ) | psql >/dev/null

(n=1000000; printf "BEGIN;"; for ((i=1;i<=$n;i++)); do printf "SAVEPOINT
s$i;"; done; printf "SELECT
pg_log_backend_memory_contexts(pg_backend_pid())") | psql >/dev/null

On my system, every of that queries led to a server crash at a number of
savepoints in the range from 174,400 to 174,700.
With your patches applied, the savepoint counter goes well beyond these
values, I settled on an amount of approximately 300,000 savepoints.
Your patches look good to me.

Best regards,
Egor Chindyaskin
Postgres Professional:

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