Hi Reka,
There is small issue in the way you suggested above. If you consider scale
down scenario, you can't actually say p2 will have min number instances. It
can be p1, if scale down happened from p1. So if we restart the stratos, RR
will select p1 as next partition right? This is not a pure RR right?
Thanks.
On Wed, Mar 4, 2015 at 12:24 AM, Reka Thirunavukkarasu <r...@wso2.com>
wrote:
> Hi Raj,
>
> I don't think that we will need another algorithm. If we implement RR in
> the way that i explained, then it will even make sure to distribute the
> members equally.
>
> For eg:
>
> p1, p2 , p3
>
> If the iteration goes as below:
> selectedIndex = -1
>
> since all the partitions has 0 instances, choose the first partition as
> the selectedIndex = 1
>
> p1 - 1 selectedIndex = 1
> p2 - 1 selectedIndex = 2
> p3 - 1 selectedIndex = 3
> p1 - 2 selectedIndex = 1
>
> stratos restart
> selectedIndex = -1
>
> p1 = 2, p2=1, p3=1 choose the first lower instances partition which will
> be p2. (sorry i missed this point earlier)
> selectedIndex=2 now
>
> then iteration can start from where it stops before the restart.
>
> p2 - 2 selectedIndex = 2
> p3 - 2 selectedIndex = 3
> p1 - 3 selectedIndex = 1
> p2 - 3 selectedIndex = 2
> p3 - 3 selectedIndex = 3
>
> If we implement RR in this way, the instances will be equally distributed
> as well.
>
> Thanks,
> Reka
>
>
> Thanks,
> Reka
>
> On Tue, Mar 3, 2015 at 11:43 AM, Rajkumar Rajaratnam <rajkum...@wso2.com>
> wrote:
>
>> So I guess we have three algorithms :)
>>
>> 1. one-after-another (It will go to next partition only if the current
>> partition is full)
>> 2. round-robin (if we implement as Reka explained above. It will always
>> select the next partition)
>> 3. name-should-be-decided (this will work as Lahiru explained above. It
>> will always distribute the members in the partitions equally)
>>
>> WDYT?
>>
>> Thanks.
>>
>> On Wed, Mar 4, 2015 at 12:01 AM, Reka Thirunavukkarasu <r...@wso2.com>
>> wrote:
>>
>>> I think that if the selectedIndex is initial value as -1, then RR should
>>> traverse through all the partitions and find out who has the minimum
>>> instances and choose that partition as the selectedIndex in the first
>>> iteration(may be we can exc). Then from the second iteration onwards, it
>>> can increase the selectedIndex by 1 to choose the next adjacent partition.
>>> This will help in the stratos restart as we don't persist the
>>> selectedIndex. WDYT?
>>>
>>> On Tue, Mar 3, 2015 at 10:53 AM, Lahiru Sandaruwan <lahi...@wso2.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Tue, Mar 3, 2015 at 11:15 PM, Rajkumar Rajaratnam <
>>>> rajkum...@wso2.com> wrote:
>>>>
>>>>> Problem is lowestInstanceCount is initially taking 0. Instead it
>>>>> should take the non terminated member count of 1st partition.
>>>>>
>>>>> To Fix,
>>>>>
>>>>> int selectedIndex = 0;
>>>>> int lowestInstanceCount =
>>>>> partitionContexts[0].getNonTerminatedMemberCount();
>>>>>
>>>>>
>>>> +1. I was thinking the same. We can start with first partition count.
>>>>
>>>> Thanks.
>>>>
>>>>> wdyt?
>>>>>
>>>>> Thanks.
>>>>>
>>>>> On Tue, Mar 3, 2015 at 10:57 PM, Rajkumar Rajaratnam <
>>>>> rajkum...@wso2.com> wrote:
>>>>>
>>>>>> Hi Lahiru,
>>>>>>
>>>>>> Actually, current logic is not working as your example. This logic
>>>>>> only uses the first partition. This will never use any other partitions.
>>>>>> See my comments within the following code.
>>>>>>
>>>>>> public PartitionContext
>>>>>> getNextScaleUpPartitionContext(PartitionContext[] partitionContexts) {
>>>>>>
>>>>>> int selectedIndex = 0;
>>>>>> int lowestInstanceCount = 0;
>>>>>>
>>>>>> for(int partitionIndex = 0; partitionIndex <
>>>>>> partitionContexts.length - 1; partitionIndex++) {
>>>>>>
>>>>>>
>>>>>> if(partitionContexts[partitionIndex].getNonTerminatedMemberCount() <
>>>>>> lowestInstanceCount) {
>>>>>>
>>>>>> *// this if condition is always false, because non terminated count
>>>>>> is always >=0*
>>>>>>
>>>>>> lowestInstanceCount =
>>>>>> partitionContexts[partitionIndex].getNonTerminatedMemberCount();
>>>>>> selectedIndex = partitionIndex;
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> *// selected index is 0 always, so round-robin will always use first
>>>>>> partition*
>>>>>>
>>>>>> if(partitionContexts[selectedIndex].getNonTerminatedMemberCount() <
>>>>>> partitionContexts[selectedIndex].getMax()) {
>>>>>>
>>>>>> if(log.isDebugEnabled()){
>>>>>> log.debug(String.format("[round-robin algorithm]
>>>>>> [scale-up] [partition] %s has space to create members. " +
>>>>>> "[non terminated count] %s [max] %s"
>>>>>> ,
>>>>>> partitionContexts[selectedIndex].getPartitionId(),
>>>>>>
>>>>>> partitionContexts[selectedIndex].getNonTerminatedMemberCount(),
>>>>>> partitionContexts[selectedIndex].getMax()));
>>>>>> }
>>>>>> return partitionContexts[selectedIndex];
>>>>>> } else {
>>>>>>
>>>>>> return null;
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> May be I am missing something here.
>>>>>>
>>>>>> Thanks.
>>>>>>
>>>>>> On Tue, Mar 3, 2015 at 10:42 PM, Lahiru Sandaruwan <lahi...@wso2.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Hi Raj,
>>>>>>>
>>>>>>> Earlier in 4.0.0 release, we have been using the partition index. If
>>>>>>> that to be worked correctly we should persist the index for each
>>>>>>> cluster.
>>>>>>>
>>>>>>> IMO there is a better way to execute the round-robin method as
>>>>>>> follows,
>>>>>>>
>>>>>>> The intention of round robin algorithm is to distribute the members
>>>>>>> in the partitions equally. Current method works as per the following
>>>>>>> example.
>>>>>>>
>>>>>>> Say we have 3 partitions, p1, p2, and p3 and max of each partition
>>>>>>> is 2.
>>>>>>>
>>>>>>> So according to the algorithm, it will select the first partition
>>>>>>> who has the lowest member count.
>>>>>>>
>>>>>>> Iteration1: It will select p1.
>>>>>>> Iteration2: It will select p2.
>>>>>>> Iteration3: It will select p3.
>>>>>>> Iteration4: It will select p1.
>>>>>>> Iteration5: It will select p2.
>>>>>>> ....
>>>>>>>
>>>>>>> Thanks.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Mar 3, 2015 at 10:22 PM, Rajkumar Rajaratnam <
>>>>>>> rajkum...@wso2.com> wrote:
>>>>>>>
>>>>>>>> Hi Devs,
>>>>>>>>
>>>>>>>> It seems to me that there is a bug in round-robin implementation of
>>>>>>>> partition algorithm.
>>>>>>>>
>>>>>>>>
>>>>>>>> https://github.com/apache/stratos/blob/0b7734f4c9f1444d064fec93bf9ac59a5883faf2/components/org.apache.stratos.autoscaler/src/main/java/org/apache/stratos/autoscaler/algorithm/RoundRobin.java#L43-L64
>>>>>>>>
>>>>>>>> Shouldn't it work based on current partition index? For example, if
>>>>>>>> the most recent instance was spin up in partition-1, the next instance
>>>>>>>> should be spin up in partition-2 and so on. According to current logic
>>>>>>>> what
>>>>>>>> is happening is, all the instance are spin up in partition-1.
>>>>>>>>
>>>>>>>> Please correct me If I am wrong.
>>>>>>>>
>>>>>>>> Thanks.
>>>>>>>>
>>>>>>>> --
>>>>>>>> Rajkumar Rajaratnam
>>>>>>>> Committer & PMC Member, Apache Stratos
>>>>>>>> Software Engineer, WSO2
>>>>>>>>
>>>>>>>> Mobile : +94777568639
>>>>>>>> Blog : rajkumarr.com
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> --
>>>>>>> Lahiru Sandaruwan
>>>>>>> Committer and PMC member, Apache Stratos,
>>>>>>> Senior Software Engineer,
>>>>>>> WSO2 Inc., http://wso2.com
>>>>>>> lean.enterprise.middleware
>>>>>>>
>>>>>>> email: lahi...@wso2.com blog: http://lahiruwrites.blogspot.com/
>>>>>>> linked-in: http://lk.linkedin.com/pub/lahiru-sandaruwan/16/153/146
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Rajkumar Rajaratnam
>>>>>> Committer & PMC Member, Apache Stratos
>>>>>> Software Engineer, WSO2
>>>>>>
>>>>>> Mobile : +94777568639
>>>>>> Blog : rajkumarr.com
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Rajkumar Rajaratnam
>>>>> Committer & PMC Member, Apache Stratos
>>>>> Software Engineer, WSO2
>>>>>
>>>>> Mobile : +94777568639
>>>>> Blog : rajkumarr.com
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> --
>>>> Lahiru Sandaruwan
>>>> Committer and PMC member, Apache Stratos,
>>>> Senior Software Engineer,
>>>> WSO2 Inc., http://wso2.com
>>>> lean.enterprise.middleware
>>>>
>>>> email: lahi...@wso2.com blog: http://lahiruwrites.blogspot.com/
>>>> linked-in: http://lk.linkedin.com/pub/lahiru-sandaruwan/16/153/146
>>>>
>>>>
>>>
>>>
>>> --
>>> Reka Thirunavukkarasu
>>> Senior Software Engineer,
>>> WSO2, Inc.:http://wso2.com,
>>> Mobile: +94776442007
>>>
>>>
>>>
>>
>>
>> --
>> Rajkumar Rajaratnam
>> Committer & PMC Member, Apache Stratos
>> Software Engineer, WSO2
>>
>> Mobile : +94777568639
>> Blog : rajkumarr.com
>>
>
>
>
> --
> Reka Thirunavukkarasu
> Senior Software Engineer,
> WSO2, Inc.:http://wso2.com,
> Mobile: +94776442007
>
>
>
--
Rajkumar Rajaratnam
Committer & PMC Member, Apache Stratos
Software Engineer, WSO2
Mobile : +94777568639
Blog : rajkumarr.com
