public inbox for [email protected]  

help / color / mirror / Atom feed

From: Heikki Linnakangas <[email protected]>
To: Robert Haas <[email protected]>
Cc: Egor Chindyaskin <[email protected]>
Cc: Sascha Kuhl <[email protected]>
Cc: [email protected]
Subject: Re: Stack overflow issue
Date: Wed, 10 Jan 2024 23:25:42 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CA+TgmoYQvB0fWJcD1DwBXgRnRFtSyRCepCTH4K3Pf7Bg0FJtKg@mail.gmail.com>
References: <[email protected]>
	<CAPvVvKCHJ_QthWsYM3SDc6Xr3PBTcOq0EOgD+y7dwbtFCz2buw@mail.gmail.com>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<CA+TgmoYQvB0fWJcD1DwBXgRnRFtSyRCepCTH4K3Pf7Bg0FJtKg@mail.gmail.com>

On 05/01/2024 19:23, Robert Haas wrote:
> On Fri, Nov 24, 2023 at 10:47 AM Heikki Linnakangas <[email protected]> wrote:
>> What do you think?
> 
> At least for 0001 and 0002, I think we should just add the stack depth checks.
> 
> With regard to 0001, CommitTransactionCommand() and friends are hard
> enough to understand as it is; they need "goto" like I need an extra
> hole in my head.
> 
> With regard to 0002, this function isn't sufficiently important to
> justify adding special-case code for an extremely rare event. We
> should just handle it the way we do in general.
> 
> I agree that in the memory-context case it might be worth expending
> some more code to be more clever. But I probably wouldn't do that for
> MemoryContextStats(); check_stack_depth() seems fine for that one.
> 
> In general, I think we should try to keep the number of places that
> handle stack overflow in "special" ways as small as possible.

The problem with CommitTransactionCommand (or rather 
AbortCurrentTransaction() which has the same problem)
and ShowTransactionStateRec is that they get called in a state where 
aborting can lead to a panic. If you add a "check_stack_depth()" to them 
and try to reproducer scripts that Egor posted, you still get a panic.

I'm not sure if MemoryContextStats() could safely elog(ERROR). But at 
least it would mask the "out of memory" that caused the stats to be 
printed in the first place.

-- 
Heikki Linnakangas
Neon (https://neon.tech)

view thread (10+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected], [email protected]
  Subject: Re: Stack overflow issue
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox