Re: Xen release cycle revisited

[Juergen Gross <jgross@suse.com>]

On 18/12/17 17:38, Julien Grall wrote:
> Hi Juergen,
> 
> On 18/12/17 16:10, Juergen Gross wrote:
>> On 18/12/17 16:57, Julien Grall wrote:
>>> Hi George,
>>>
>>> On 18/12/17 14:56, George Dunlap wrote:
>>>> On Fri, Dec 15, 2017 at 2:54 PM, Juergen Gross <jgross@suse.com> wrote:
>>>>> On 14/12/17 14:13, Juergen Gross wrote:
>>>>>> On 14/12/17 13:43, Julien Grall wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 14/12/17 11:38, Juergen Gross wrote:
>>>>>>>> On 14/12/17 12:28, Julien Grall wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 14/12/17 07:56, Juergen Gross wrote:
>>>>>>>>>> Hi all,
>>>>>>>>>
>>>>>>>>> Hi Juergen,
>>>>>>>>>
>>>>>>>>> I would recommend to CC committers on that thread, so your thread
>>>>>>>>> don't
>>>>>>>>> get lost in the xen-devel meanders :).
>>>>>>>>>
>>>>>>>>>> with 4.10 more or less finished it is time to plan for the next
>>>>>>>>>> release
>>>>>>>>>> 4.11. Since 4.7 we are using a 6 month release cycle [1]
>>>>>>>>>> targeting to
>>>>>>>>>> release in June and December.
>>>>>>>>>>
>>>>>>>>>> While this worked reasonably well for 4.7, 4.8 and 4.9 we had
>>>>>>>>>> some
>>>>>>>>>> difficulties with 4.10: bad luck with security patch timing
>>>>>>>>>> shifted the
>>>>>>>>>> 4.10 release more towards mid of December. Doing thorough
>>>>>>>>>> testing of
>>>>>>>>>> the
>>>>>>>>>> latest security patches and trying to release at least 10 days
>>>>>>>>>> before
>>>>>>>>>> Christmas seemed to be almost mutually exclusive goals.
>>>>>>>>>>
>>>>>>>>>> So what do we learn from this experience?
>>>>>>>>>>
>>>>>>>>>> 1. Should we think about other planned release dates (e.g. May
>>>>>>>>>> and
>>>>>>>>>>        November - would that collide with any holiday season)?
>>>>>>>>>>
>>>>>>>>>> 2. Shouldn't we have tried to include the latest security
>>>>>>>>>> patches in
>>>>>>>>>>        4.10, resulting in the need for 4.10.1 at once?
>>>>>>>>>
>>>>>>>>> I am not sure to understand this questions here.
>>>>>>>>
>>>>>>>> Hmm, yes, this is somehow garbled.
>>>>>>>>
>>>>>>>> Next try:
>>>>>>>>
>>>>>>>> 2. Should we have released 4.10 without those late security
>>>>>>>> patches,
>>>>>>>>       resulting in the need for 4.10.1 at once?
>>>>>>>
>>>>>>> We were not ready to release on the 2nd December. This would have
>>>>>>> put
>>>>>>> the release date too close to XSAs published date. The risk was
>>>>>>> that the
>>>>>>> security issues announcement would overshadow the release
>>>>>>> announcement.
>>>>>>
>>>>>> Okay. So for me it seems as if a planned release early December is
>>>>>> the
>>>>>> main problem: either the release slips no more than 2 weeks or it
>>>>>> will
>>>>>> slip for more than 5 weeks.
>>>>>>
>>>>>> Having only 2 weeks of spare time is a major risk.
>>>>>
>>>>> What I'd like to suggest is to move the target release dates to early
>>>>> May and November. Or would this create a conflict with any holiday
>>>>> season we care about?
>>>>
>>>> I think one concern was that if we release in early May, the feature
>>>> freeze would be early March, which will often be right after Chinese
>>>> New Year (a bit like having the feature freeze on January 5).
>>>>
>>>> But having the feature freeze up shortly after a major holiday is
>>>> probably less bad than having the release shortly before a major
>>>> holiday (as we have had this time).
>>> Yu would unofficially put the feature freeze for anyone "affected" by
>>> the major holidays.
>>>
>>> So it might be wiser to move the feature freeze before the holidays.
>>> This would help planning and avoid adding frustration around the feature
>>> freeze.
>>
>> Hmm, really?
>>
>> So I should freeze one or two weeks earlier just because someone _might_
>> be on vacation? So I would eventually delay a major feature from someone
>> in Europe because of Chinese holidays? I don't think this is a good
>> idea.
> Chinese NY is quite important in China. Knowing that they are
> contributing a lot to Xen, it is not only someone but an important part
> of the contributors.
> 
> Any major holidays affecting Europe/US is likely going to affect the
> release. Mostly because the a major part of the maintainers are in
> Europe/US today.
> 
> So you would delay feature from someone in China because of European/US
> holidays. How this would this be fine compare to the invert?

So I don't get why moving the freeze date _before_ the holidays as you
suggested would not delay that feature. I can't believe that making the
development phase shorter will help more features to be finished.

Putting the freeze date at before the holidays will just hurt _all_
developers while for those being on vacation nothing changes regardless
whether the freeze is at the beginning or at the end of their holidays.

What _is_ changing, though, is their ability to react on a potential bug
when the freeze date has come: with the freeze date at the start of
their holidays they will be able to fix the bug only after the end of
their holidays, so the freeze period is longer without any win for the
whole project.

What we should try to avoid in any case is a major part of the community
being on vacation between freeze date and release of the new version. As
we can't know for sure how long this phase will be we should make sure
to make it as long as possible, so setting the freeze date at the end of
a holidays season is just the right thing to do.

I'm open for other suggestions regarding the dates, of course. So I
believe the first thing we should do is to write down the holidays we'd
like to avoid. Then we should find the two longest time spans without
any major holidays about 6 months apart to settle the freeze and the
potential release dates. The freeze dates should be as early as possible
allowing for the maximum time until the release dates.

So IMO we want to avoid the following holidays seasons:
- Chinese new year: 1 week after Jan 22 ... Feb 17
- Main holidays season Europe/US: July, August
- Christmas: Dec 24 - Jan 1 (maybe longer?)
Adding e.g. Eastern would make it very hard to find a suitable date:
effectively mid of December until end of February are already blocked by
above dates. Adding Eastern would add 2 further months unless we adapt
each year individually (which is possible, of course).


Juergen

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