[Gluster-Maintainers] inclusion of multi-threaded self-heal feature in 3.7.12

[Pranith Kumar Karampuri]

On 04/12/2016 12:05 PM, Niels de Vos wrote:
> On Tue, Apr 12, 2016 at 11:50:23AM +0530, Pranith Kumar Karampuri wrote:
>>
>> On 04/11/2016 09:58 PM, Vijay Bellur wrote:
>>> On 04/11/2016 08:02 AM, Niels de Vos wrote:
>>>> On Mon, Apr 11, 2016 at 05:00:22PM +0530, Pranith Kumar Karampuri wrote:
>>>>> hi,
>>>>>          I am thinking of getting multi-threaded self-heal patch in
>>>>> 3.7.12
>>>>> release as it is not a big code change, could you let me know if
>>>>> anyone has
>>>>> any issues with this?
>>>> Is this safe to use when there is no rpc throttling?
>> Default number of parallel heals is still '1'. It will be 1 until we have
>> some form of throttling of traffic, which we are targeting for 3.8.
>>
>>> A few more questions:
>>>
>>> 1. What is the impact on stability due to this patch?
>> So far we haven't found any problems with this patch. It has been tested for
>> around a month before it is sent upstream for merge.
>>> 2. What scenarios would we want this feature to be turned on? Basically an
>>> admin guide update about these scenarios would be useful.
>> I can send a document about this.
>>> 3. What kind of tests have been done with this feature?
>> Most of the tests include perf comparison of VM images/sharded images which
>> showed promising results.
>>> 4. Are there tests that we want to cover but have not been able to
>>> complete for this feature?
>> Hmm... not really.
> I'm not completely confident that this should be backported to 3.7. We
> should focus on backporting bug fixes and leave the featurs for next
> releases. We have seen a few regression in the 3.7 stable branch because
> of agressive backporting of features. Potential undiscovered issues are
> something we should expect for each new feature, and backporting them
> always comes with a risk. I really want to keep the promise to users
> that 3.7 is a stable version.

Give me a list of things that need to be done for building confidence 
for inclusion of this patch and I will get it done.
At the moment like I said it already underwent more than a month of 
testing and I feel it is stable. I also as a maintainer really want to 
keep the promise to the users that 3.7. branch is stable and with good 
performance.

>
> You have to come with really good arguments to convince anyone from
> including a feature in stable branches. Disabling (or in this case one
> parallel heal) does not make much for backports.

Really good arguments is subjective Niels. Most of the users have been 
asking for both this feature and throttling of self-heal traffic for 
years, I feel it is stable enough to get into a branch. We are also 
keeping the defaults such that users who don't care about this won't 
have any surprises. I am happy to get anything and everything that the 
maintainer for 3.7.12 ask for this patch to be included in 3.7.12 but I 
want this to get in for 3.7.12.

Pranith
>
> Try again? Thanks,
> Niels