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  • Bug#1106083: scilab: FTBFS: autobuilder hangs when using the kernel of

    From Santiago Vila@21:1/5 to All on Fri Jul 4 19:50:01 2025
    Option --max-parallel=1 did not help (same failure rate as before).

    I'm open for ideas.

    Thanks.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From =?utf-8?Q?=C3=89tienne?= Mollier@21:1/5 to All on Wed Jul 9 21:20:01 2025
    Hi Santiago,

    Thanks for the details about the question of memory usage, given
    the failure mode and your own diligent implementation details, I
    believe this can reasonably be ruled out.

    Santiago Vila, on 2025-07-09:
    Étienne, on 2025-07-09:
    I also notice that the kernel run is the cloud variant. Maybe
    having a look at differences with the plain kernel could reveal
    some clues? (assuming that the problem has not disappeared from
    6.12.32 to 6.12.33…)

    That would also be a possibility in theory, but I think it's unlikely.

    Right, I tried to isolate the configuration options differences,
    and they seem to boil down to:

    * very many hardware specific options being disabled, because
    we're sure that the kernel will run on top of a hypervisor
    with somewhat homogenous context;
    * a couple of hypervisor and cloud specific options are
    enabled, or inlined instead of modular, to survive early
    boot sequence in cloud context.

    I admit that I don't see any good reason for such changes to
    trigger a chain reaction resulting in a hangup.

    In case it matters, the failure rates that I got recently were:

    10% (5 out of 50) on systems with 1 CPU
    78% (39 out of 50) on systems with 2 CPUs.

    I suspect of a race condition of some kind, so if you are still
    willing to try different things (as opposed to directly trying
    in my VM after I finish my last test build), I would try
    bulding the package on a self-hosted qemu/kvm machine
    with exactly 2 CPUs. You can probably achieve the same
    effect by using GRUB_CMDLINE_LINUX="nr_cpus=2" (i.e.
    modify /etc/default/grub, run update-grub and reboot).

    (btw: Building scilab in unstable 100 times as we speak, I believe
    that by night I will be able to tell the outcome).

    Acknowledged, I run also a couple of builds locally (as long as
    battery capacity allows) and see if I can observe something
    interesting if I manage to reproduce a hangup. If I also have a
    78% failure rate, I may have a reasonable chance to see
    something tonight.

    Have a nice day, :)
    --
    Étienne Mollier <emollier@emlwks999.eu>
    Fingerprint: 8f91 b227 c7d6 f2b1 948c 8236 793c f67e 8f0d 11da
    Sent from my alarm clock.

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    --- SoupGate-Win32 v1.05
    * Or
  • From =?utf-8?Q?=C3=89tienne?= Mollier@21:1/5 to All on Fri Jul 11 09:20:01 2025
    Hi Santiago,

    Santiago Vila, on 2025-07-11:
    On Fri, Jul 11, 2025 at 12:09:48AM +0200, Étienne Mollier wrote:
    0. if I trust Helmut Grohne, I cannot empty the entropy pool;
    maybe I can just make it more strained, so the behavior may
    be unreproducible to some extent: for instance I have not
    managed to reproduce the behavior straight on my laptop;

    I would be quite surprised if the entropy pool was the problem.

    Right, I have no third occurrence in a row: my build went
    through this morning.

    I guess that at some point we should probably tell upstream about this.

    We mostly know what the problem is not about, but we still don't
    know what the problem is precisely. I agree informing upstream
    shouldn't hurt, but I don't really expect with the element we
    have that it will be much actionable unfortunately, but one
    never knows.

    Have a nice day, :)
    --
    .''`. Étienne Mollier <emollier@debian.org>
    : :' : pgp: 8f91 b227 c7d6 f2b1 948c 8236 793c f67e 8f0d 11da
    `. `' sent from my alarm clock
    `-

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    --- SoupG
  • From =?utf-8?Q?=C3=89tienne?= Mollier@21:1/5 to All on Sat Jul 12 18:10:01 2025
    Control: forwarded -1 https://gitlab.com/scilab/scilab/-/issues/17461
    Control: found -1 2024.1.0+dfsg-6

    Hi Santiago,

    Étienne Mollier, on 2025-07-11:
    Santiago Vila, on 2025-07-11:
    I guess that at some point we should probably tell upstream about this.

    We mostly know what the problem is not about, but we still don't
    know what the problem is precisely. I agree informing upstream
    shouldn't hurt, but I don't really expect with the element we
    have that it will be much actionable unfortunately, but one
    never knows.

    I gathered some information that was missing and could
    reasonably be determined with further testing and opened the
    scilab upstream issue #17461; see the Forwarded field. Feel
    free to complement if you believe some further information might
    be worth forwarding.

    Short summary of new items compared to what has been already
    discussed in the present thread is:

    * I reproduced the issue on a virtual machine running the
    plain Linux kernel 6.12.y+deb13-amd64 instead of the cloud
    variant;
    * I never managed to reproduce the issue on bare metal (not
    news, but it is worth highlighting this only occurred on
    virtual machines so far);
    * I attempted the build with the later openjdk 25 instead of
    the default openjdk 21, per a suggestion from Helmut, but it
    seems the issue was also occurring here.

    Have a nice day, :)
    --
    .''`. Étienne Mollier <emollier@debian.org>
    : :' : pgp: 8f91 b227 c7d6 f2b1 948c 8236 793c f67e 8f0d 11da
    `. `' sent from my alarm clock
    `-

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    --- SoupG
  • From =?utf-8?Q?=C3=89tienne?= Mollier@21:1/5 to All on Sun Jul 13 11:30:01 2025
    Hi Pierre, Hi Santiago,

    Pierre Gruet, on 2025-07-13:
    However, my feeling is that the bug is not RC, since it shows up only in
    VMs: in practice it does not affect the autobuilders nor the developers on their individual machines. What do you think?

    Thank you for your input, I have been trying to gather enough
    elements to either pinpoint the root cause of the issue, or
    assess whether the issue would be critical for the upcoming
    release. In the current circumstances, I am okay with a
    reduction of the severity to "important" for the reasons you
    mention. Santiago, thanks for your invaluable help this far,
    does a severity reduction sound reasonable to you at this stage?

    Have a nice day both, :)
    --
    .''`. Étienne Mollier <emollier@debian.org>
    : :' : pgp: 8f91 b227 c7d6 f2b1 948c 8236 793c f67e 8f0d 11da
    `. `' sent from my alarm clock
    `-

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    --- SoupG