[Lxc-users] concurrent aptitude/dpkg runs in separate containers --> bork bork bork

[Trent W. Buck]

twb at cybersource.com.au (Trent W. Buck)
writes:

> I'm being a bit more patient than last time, and I think they ARE
> proceeding, just REALLY slowly.  Meanwhile aptitude consumes a 100% of a
> core busy-waiting for a response from dpkg :-/
>
> They look like this:
>
>     $ ssh omega cat /proc/7713/stack
>     Warning: Permanently added 'omega,192.168.155.22' (RSA) to the list of known hosts.
>     [<ffffffff811669b7>] sync_inodes_sb+0x87/0xb0
>     [<ffffffff8116b292>] __sync_filesystem+0x82/0x90
>     [<ffffffff8116b379>] sync_filesystems+0xd9/0x130
>     [<ffffffff8116b431>] sys_sync+0x21/0x40
>     [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b
>     [<ffffffffffffffff>] 0xffffffffffffffff
>
>     $ ssh omega cat /proc/5619/stack
>     Warning: Permanently added 'omega,192.168.155.22' (RSA) to the list of known hosts.
>     [<ffffffff81222865>] jbd2_log_wait_commit+0xc5/0x150
>     [<ffffffff811d7a2c>] ext4_sync_file+0x13c/0x2e0
>     [<ffffffff8116b051>] vfs_fsync_range+0xa1/0xe0
>     [<ffffffff8116b0fd>] vfs_fsync+0x1d/0x20
>     [<ffffffff8116b13e>] do_fsync+0x3e/0x60
>     [<ffffffff8116b190>] sys_fsync+0x10/0x20
>     [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b
>     [<ffffffffffffffff>] 0xffffffffffffffff

And here's one that is well and truly wedged:

    root at omega:~# cat /proc/31430/stack
    [<ffffffff811669b7>] sync_inodes_sb+0x87/0xb0
    [<ffffffff8116b292>] __sync_filesystem+0x82/0x90
    [<ffffffff8116b379>] sync_filesystems+0xd9/0x130
    [<ffffffff8116b431>] sys_sync+0x21/0x40
    [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b
    [<ffffffffffffffff>] 0xffffffffffffffff

In that case, even kill -SEGV'ing upstart won't stop it.  I got that
with only a single dpkg run (i.e. no concurrency), after switching the
container's rootfs from ext4 to ext3, and forcing dpkg[0] to be upgraded
before anything else.  Sigh...

I'm THIS CLOSE to giving up and wrapping apt-get in libeatmydata.

[0] I did this because I noticed that lucid's dpkg still suffers from

      http://bugs.debian.org/578635
      http://bugs.debian.org/605009
      https://launchpad.net/bugs/570805

    But lucid-updates & lucid-security both contain a version that
    contains CLAIMS to address the first of those.