[Aptitude-devel] Strange issue with aptitude causing 100% cpu usage on Sid amd64 DomU

[Daniel Hartwig]

On 4 July 2012 06:47, Axel Beckert <abe at debian.org> wrote:
> Hi,
>
> since about a day or such my Sid DomU (Xen virtual machine) gets
> extremely sluggish as soon as I start "aptitude -u". It even throws
> kernel messages like this several times during the (very slow) package
> update:
>
> Message from syslogd at kiva6 at Jul  4 00:02:00 ...
>  kernel:[7736331.176014] BUG: soft lockup - CPU#0 stuck for 23s! [ksoftirqd/0:3]
>

This is during the list update?

> If I first run apt-get update and then aptitude without -u, everything
> seems fine for a moment, but then all mentioned processes go on 100%
> cpu again as soon as the view is generated (maybe a little bit
> earlier, too, but not as soon as the blue bars are shown on top and
> bottom), funnily except aptitude itself. It stays at 5% to 10%.

And this is before you actually see the list of packages?

Have not encountered these issues myself.  Similar experiences on the
BTS often appear due to the problem resolver and/or threading issues,
especially with multiple CPU.  Recent reports involving the resolver:
#631071, #668544.

Is Aptitude::Auto-Upgrade enabled?

Multi-arch?

Based on your command-line log showing conflicts with safe-upgrade, I
would suspect the resolver at fault here.

Trace logs or a backtrace from the point(s) where the program is being
sluggish might help, though can be painful to inspect when threading
issues are involved.  Trace logs:

# aptitude -u --log-file=resolver.log --log-resolver

Please kill the program while it is being sluggish so the log tail is
hot.  And same again without -u.

> "which-pkg-broke aptitude" shows the following potential packages
> which could have broken aptitude recently:
>

These updates don't look suspicious:
> libdb5.1:amd64 [apt-utils]
> debconf [only used during install run]
> dpkg [install run]
> libxapian22 [only used for search]
> libapt-pkg4.12:amd64 [changelog looks benign, although recent change to mmap behaviour…]

Most recent upload has several changes to pthreads which /seem/
unrelated, however, you could try downgrading to the versions
previously installed:
> libc-bin
> libc6:amd64
> multiarch-support

Regards