From: | Tomasz Zielonka <tomek(at)mult(dot)i(dot)pl> |
---|---|
To: | PostgreSQL bugs <pgsql-bugs(at)postgresql(dot)org> |
Subject: | Strange deadlock problem on simple concurrent SELECT/LOCK TABLE transactions |
Date: | 2001-08-24 16:19:57 |
Message-ID: | 20010824181957.A26882@mult.i.pl |
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Lists: | pgsql-bugs |
Hi!
I'm using PostgreSQL 7.1.3 on Intel PIII, Linux 2.4.8, Slackware 8.0,
compiled with egcs 2.91.66 (the same on 7.1.2 / 2.95.3).
I'm encountering very strange deadlock situation. Strange, because after
this deadlock occurs, even with no active postgres processes (postmaster only),
when I connect with psql I can't select anything from affected table.
Here is a (almost) minimal test:
CREATE TABLE items (
id INTEGER NOT NULL,
amount FLOAT NOT NULL,
PRIMARY KEY (id)
);
-- amount field is probably no longer necessary, but I haven't tested without
-- it
And run this in TWO concurrent sessions:
$ yes 'begin; select * from items; lock table items; commit;' | psql
I get deadlock here quite fast.
Both processes freeze on next select.
Stop them (ctrl-c).
ps xa shows only postmaster process, no postgres ones.
Now connect which psql and try to 'SELECT * FROM items'.
Freeze again.
What do you think?
Have a nice weekend :)
Greetings,
Tom
--
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