Re: [gentoo-user] unclear (to me) errors from portage

[Alan McKinnon]

On 08/08/2014 15:11, gottlieb@×××.edu wrote:
> On Fri, Aug 08 2014, wraeth@×××××××××.au wrote:
>
>> On Fri, 2014-08-08 at 08:23 +0200, J. Roeleveld wrote:
>>> I notice a few perl blockers.
>>> You could try the following:
>>>
>>> # emerge -vuD1 $(qlist -IC 'virtual/perl-*')
>>> # perl-cleaner --all -v -- -v
>>>
>>> And then retry to update world.
>>> I've been encountering some perl blockages myself, and this cleared it up for
>>> me.
>>
>> I also notice a conflict between
>>
>>   media-video/ffmpeg-1.2.6-r1::gentoo, ebuild scheduled for merge
>>
>>   media-video/libav-9.14::gentoo, installed
>>
>> You may want to include which one you prefer (ffmpeg or libav) in your
>> call to emerge, and possibly include "--with-bdeps=y":
>>
>>   `emerge -1uDNav --with-bdeps=y @world media-video/<selection>`
>>
>> Note the addition of the '-1' or "--oneshot" option - you should always
>> use this when specifying libraries to emerge.
>
> (Yes about --oneshot)
>
> The choice of ffmpeg vs libav seems non-deterministic ??
>
> I have a shell open directly on the machine e6510 and am ssh'ed
> into e6510 from another machine
>
> On the direct shell two successive runs of
>
> e6510 ~ # emerge --update --changed-use --deep  @world
> (I have EMERGE_DEFAULT_OPTS="--ask --deep --tree --verbose --jobs
> --load-average=5")
>
> gave different results.  The first one gave the error msg about libav
> and ffmpeg conflicting; the second gave no error and is ready to go.  I
> looked at the tree output and see that the successful one has an
> uninstall of libav right before the install line for ffmpeg.  The
> unsuccessful one does not have that line.
>
> On the ssh shell, the first few tries gave the conflict error msg; but
> then one succeeded (again proposing to uninstall libav).
>
> Perhaps the dependency search uses multiple threads??
>
> Since I must choose between libav and ffmpeg, I will use the choice that
> portage (sometimes) makes and run the successful emerge command,
> i.e. say yes to the question from --ask.
>
> Is this nondeterminism documented or have I done something wrong.

It's working as designed. The various deps for ffmpeg vs libav allow
either one to satisfy the dep, especially if you have virtual/ffmpeg in
world.

This new dynamic dep stuff allows portage a degree of freedom in
selecting such providers and sometimes it decides to use the one you
don't have. To satisfy that decision, it must then uninstall what you
have. I suspect the root cause of such apparently random behaviour is
that portage is loading your installed apps into an associative array,
and the order if items in those are random.

Two solutions::

1. use --backtrack <some big number>
   this tells portage to search deeper and hopefully realize you
   already have libav

2. Put libav in world, this will stop portage from trying to be helpful



I prefer the second choice as it makes things very explicit.


-- 
Alan McKinnon
alan.mckinnon@×××××.com