Registry save: apparently circular structure being printed

Registry save: apparently circular structure being printed

[Bob Newell]

I came across something that undoubtedly will be hard to reproduce ---
until some ultimately inconvenient moment. I had just set up a half
dozen or so RSS feeds for gnus (using the simple G R method). Now, the
RSS part may or may not be relevant, but I did load a lot of articles
and make a lot of changes to the feeds, killing some, adding some,
etc., for quite a while.

I have code that ensures gnus is properly closed out on exiting Emacs,
and that includes saving the registry (gnus takes care of it on its
own exit, it seems).

At the point of saving the registry, I started getting the message
"Apparently circular structure being printed". This persisted until I
killed emacs directly and deleted the gnus registry. Not exactly an
optimal solution!

I realize this is obscure, and my report is necessarily bare-bones,
but has anyone ever seen anything like this?

In the interim I'm increasing max-lisp-eval-depth from the default 800
to 3000, just before gnus is closed out. I have no idea if this will
be sufficient and will only find out when and if the problem returns.

-- 
Bob Newell
Honolulu, Hawai`i

Via Linux/Emacs/Gnus/BBDB.

Re: Registry save: apparently circular structure being printed

[Eric Abrahamsen]

Bob Newell <bobnewell@bobnewell.net> writes:

> I came across something that undoubtedly will be hard to reproduce ---
> until some ultimately inconvenient moment. I had just set up a half
> dozen or so RSS feeds for gnus (using the simple G R method). Now, the
> RSS part may or may not be relevant, but I did load a lot of articles
> and make a lot of changes to the feeds, killing some, adding some,
> etc., for quite a while.
>
> I have code that ensures gnus is properly closed out on exiting Emacs,
> and that includes saving the registry (gnus takes care of it on its
> own exit, it seems).
>
> At the point of saving the registry, I started getting the message
> "Apparently circular structure being printed". This persisted until I
> killed emacs directly and deleted the gnus registry. Not exactly an
> optimal solution!
>
> I realize this is obscure, and my report is necessarily bare-bones,
> but has anyone ever seen anything like this?

Unfortunately, yes, I think Uwe Brauer reported something similar a
while ago. Can you tell me what version of emacs you're using?

I'm 80% confident that this has to do with something that changed in
Emacs 26 about the way objects are represented: it used to be that the
registry could simply write all its contents to disk, but now it needs
special processing. A while ago I provided a naive fix that ended up
causing further bugs, which I'm not yet done stamping out. I don't know
where the "circular structure" error is coming from, actually, but it
seems very likely that it's related.

Tell me your emacs version, and if you can, please provide a backtrace
that I can compare to Uwe's, and see if I can figure this out.

Yours,
Eric

Re: Registry save: apparently circular structure being printed

[Tom Tromey]

>>>>> "Eric" == Eric Abrahamsen <eric@ericabrahamsen.net> writes:

>> At the point of saving the registry, I started getting the message
>> "Apparently circular structure being printed". This persisted until I
>> killed emacs directly and deleted the gnus registry. Not exactly an
>> optimal solution!
>> 
>> I realize this is obscure, and my report is necessarily bare-bones,
>> but has anyone ever seen anything like this?

Eric> Unfortunately, yes, I think Uwe Brauer reported something similar a
Eric> while ago. Can you tell me what version of emacs you're using?

[...]

Eric> Tell me your emacs version, and if you can, please provide a backtrace
Eric> that I can compare to Uwe's, and see if I can figure this out.

I've encountered this as well, and I filed it as:

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31978

I was using Emacs 26 and a stack trace is included there.

Tom

Re: Registry save: apparently circular structure being printed

[Eric Abrahamsen]

On 07/31/18 09:18 AM, Tom Tromey wrote:
>>>>>> "Eric" == Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>>> At the point of saving the registry, I started getting the message
>>> "Apparently circular structure being printed". This persisted until I
>>> killed emacs directly and deleted the gnus registry. Not exactly an
>>> optimal solution!
>>> 
>>> I realize this is obscure, and my report is necessarily bare-bones,
>>> but has anyone ever seen anything like this?
>
> Eric> Unfortunately, yes, I think Uwe Brauer reported something similar a
> Eric> while ago. Can you tell me what version of emacs you're using?
>
> [...]
>
> Eric> Tell me your emacs version, and if you can, please provide a backtrace
> Eric> that I can compare to Uwe's, and see if I can figure this out.
>
> I've encountered this as well, and I filed it as:
>
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31978
>
> I was using Emacs 26 and a stack trace is included there.

I responded to that bug report! Did you see my note about using the
commit from master?

Eric

Re: Registry save: apparently circular structure being printed

[Tom Tromey]

>>>>> "Eric" == Eric Abrahamsen <eric@ericabrahamsen.net> writes:

Eric> I responded to that bug report! Did you see my note about using the
Eric> commit from master?

Nope, sorry.  Sometimes I seem not to get email from debbugs, I don't
know why.

I will give that a try soon.  Thank you.

Tom