stratos-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Imesh Gunaratne <im...@apache.org>
Subject Re: Cause of Scale Down Logic Issue was Identified
Date Fri, 18 Apr 2014 05:04:42 GMT
Thanks Azeez! Yes, completely agree.


On Fri, Apr 18, 2014 at 9:56 AM, Afkham Azeez <afkham@gmail.com> wrote:

>
>
>
> On Fri, Apr 18, 2014 at 1:12 AM, Imesh Gunaratne <imesh@apache.org> wrote:
>
>> Hi,
>>
>> During last few days we noticed an intermittent issue in scale down logic
>> and it was reported in STRATOS-614.
>>
>> Today after doing some thorough tests we identified the cause of this
>> issue. The problem was with the topology event receiver queue. Since this
>> queue was designed as a singleton,
>>
>
> Singletons should be avoided as much as possible, and used with caution.
> Some even consider it an anti-pattern.
>
>
>> it was being shared among multiple event receivers in Single JVM mode. As
>> a result event messages were unevenly being dequeued to message processors
>> and some event receivers were missing events randomly.
>>
>> This problem was also there in Tenant event receiver, Health Stat event
>> receiver and Instance Notifier event receiver. I have now fixed this by
>> introducing a message queue for each event receiver instance created.
>>
>> I have now committed this fix to master branch. Will do few more flow
>> tests to verify the correction and update with the results soon.
>>
>> Thanks
>>
>> --
>> Imesh Gunaratne
>>
>> Technical Lead, WSO2
>> Committer & PPMC Member, Apache Stratos
>>
>
>
>
> --
> *Afkham Azeez*
> Director of Architecture; WSO2, Inc.; http://wso2.com,
> *Member; Apache Software Foundation; **http://www.apache.org/*<http://www.apache.org/>
>
> *email: **azeez@wso2.com* <azeez@wso2.com>
> * cell: +94 77 3320919 <%2B94%2077%203320919> blog: *
> *http://blog.afkham.org* <http://blog.afkham.org>
> *twitter: **http://twitter.com/afkham_azeez*<http://twitter.com/afkham_azeez>
> * linked-in: **http://lk.linkedin.com/in/afkhamazeez
> <http://lk.linkedin.com/in/afkhamazeez>*
>
> *Lean . Enterprise . Middleware*
>
>


-- 
Imesh Gunaratne

Technical Lead, WSO2
Committer & PPMC Member, Apache Stratos

Mime
View raw message