From: "Ludovic Courtès" <ludo@gnu.org>
To: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Cc: Artyom Poptsov <poptsov.artyom@gmail.com>, 42740@debbugs.gnu.org
Subject: bug#42740: Segfault in libssh during ‘guix copy’
Date: Tue, 01 Sep 2020 22:57:58 +0200 [thread overview]
Message-ID: <87y2lt6wq1.fsf@gnu.org> (raw)
In-Reply-To: <87eenlzjkn.fsf@gmail.com> (Maxim Cournoyer's message of "Tue, 01 Sep 2020 09:56:56 -0400")
Hello!
Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
> Ludovic Courtès <ludo@gnu.org> writes:
[...]
>> I’ve pushed this change on our side to explicitly close channels and
>> sessions:
>>
>> https://git.savannah.gnu.org/cgit/guix.git/commit/?id=61fe9ced7da7eefceb931af0cb7363b721f5bdd6
>>
>> This workaround is similar to that of 2017:
>>
>> https://git.savannah.gnu.org/cgit/guix.git/commit/?id=8e469b67f95cfe5b95405b503b8ee315fdf8ce66
>>
>> It’s really just a workaround so I think we should fix the core issue in
>> Guile-SSH (or libssh) so it doesn’t pop up again next month—it’s hard to
>> ensure code that opens a channel explicitly closes it.
>
> Do you think the issue lies in guile-ssh or in libssh itself? Sorry for
> not having caught these problems earlier; it seemed to work reliably
> when I last tested it.
No worries; these issues are non-deterministic and we can spend months
without noticing.
Perhaps libssh is documented as not being thread-safe, in which case
it’s up to its users to do the right thing. In that case, the problem
would be in Guile-SSH, since in Guile 2.2/3.0 finalizers can be called
from a separate thread.
It’s also probably easier to fix in Guile-SSH (technically & socially).
>> Anyway, I would welcome tests using ‘guix copy’, ‘guix deploy’, and
>> offloading. (For offloading, make sure to run the daemon from your
>> build tree.)
>
> While attempting to use offload on the core-updates branch, I
> encountered stalls and file errors, but with your patch it seems to work
> reliable (it's been offloading builds for the last 15 minutes or so
> without interruption).
>
> So your workaround fixes seem to work as intended.
Good, thanks for testing. We should update the ‘guix’ package again
soonish.
Ludo’.
next prev parent reply other threads:[~2020-09-01 20:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-07 9:24 bug#42740: Segfault in libssh during ‘guix copy’ Ludovic Courtès
2020-08-07 18:36 ` Artyom V. Poptsov
2020-08-09 8:48 ` Artyom Poptsov
2020-08-17 3:31 ` Maxim Cournoyer
2020-08-23 16:31 ` Ludovic Courtès
2020-09-15 2:05 ` Maxim Cournoyer
2020-09-15 8:14 ` Ludovic Courtès
2020-09-15 13:48 ` Maxim Cournoyer
2020-08-29 13:31 ` Ludovic Courtès
2020-08-29 14:31 ` Ludovic Courtès
2020-09-01 13:56 ` Maxim Cournoyer
2020-09-01 20:57 ` Ludovic Courtès [this message]
2020-09-02 21:19 ` Ludovic Courtès
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