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
