Re: [gentoo-user] Re: Re: Emerge order not deterministic !?

[Alan McKinnon]

On 12/11/2015 10:48, Jörg Schaible wrote:
> Alan McKinnon wrote:
>
>> On 12/11/2015 10:29, Jörg Schaible wrote:
>>> Alan McKinnon wrote:
>>>
>>>> On 11/11/2015 21:35, Walter Dnes wrote:
>>>>>   Ongoing installation.  I looked at 2 instances of
>>>>> "emerge -pv x11-base/xorg-server" and the order was somewhat different.
>>>>> Here are a couple of outputs, just a few seconds apart.  Is this a bug
>>>>> or a feature?  See attachments.
>>>>>
>>>>
>>>>
>>>> Emerge order is not deterministic, especially with parallel builds. The
>>>> reason is that it does not need to be according to the dep graph - if
>>>> two packages are at the same level and do not depend on each other, then
>>>> the order they are built in does not affect the final result.
>>>> Practically all parallel processing works this way.
>>>>
>>>> What is deterministic, is that if you build the same set of packages
>>>> twice and even if portage does them in different order, the binaries
>>>> produced are functionally identical
>>>
>>> Hmmm. And how can you then ever use
>>>
>>>   emerge --resume --skip-fist
>>>
>>> if not even the first build is deterministic? I skip the first package
>>> anyway only if the problematic package is the first one to build after
>>> resume, but if I cannot even rely on that?
>>
>>
>> Because it re-uses the previous build order, not re-generate a new one.
>
> That's simply not true. Emerge resume calculates the order again and for me
> it starts often with a different package.

I've never noticed that. For me --skip-first has always skipped the
correct first package (the one that previously failed).

As long as a known build failure is not in the --resume list, I don't
care what the build order is because it is irrelevant. The only time it
becomes relevant is when an ebuild has a bug such as a missing dep. But
that's a bug in the ebuild and is fixed there.


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