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From Saminda Wijeratne <samin...@gmail.com>
Subject Re: Orchestration Component implementation review
Date Mon, 20 Jan 2014 05:13:56 GMT
On Sun, Jan 19, 2014 at 8:48 PM, Amila Jayasekara
<thejaka.amila@gmail.com>wrote:

>
>
>
> On Sun, Jan 19, 2014 at 5:33 PM, Lahiru Gunathilake <glahiru@gmail.com>wrote:
>
>> Hi Chathuri,
>>
>>
>> On Fri, Jan 17, 2014 at 11:40 AM, Chathuri Wimalasena <
>> kamalasini@gmail.com> wrote:
>>
>>> Orchestrator table has only the current state (updated state). Previous
>>> statuses should be saved in the GFac_Job_Status table.
>>>
>> Since the order of the steps are defined, do we need to store the
>> previous states ?
>>
>
> I am also curious to know why we need to store previous states. We have a
> define state diagram for a job. Also we have log files if we want to debug
> a specific issue related to job statuses. So I am not sure why we need to
> store previous job states. Also who and when we will access previous job
> states ?
>
It is not meant for debugging but essentially could be used very easily if
needed unlike using a log file. This feature gets enabled only if
"enable.application.job.status.history" is set in the properties file. Once
set,the history table gets updated automatically without the intervention
of the GFac. Thus this feature doesn't create any overhead to the system
when its not enabled.
Why store previous statuses? Collecting statistics. Airavata itself is not
yet advance enough to use such data to optimize its scheduling but the
gateway could use the data if they need it.

>
> Thanks
> Amila
>
>
>>
>> Regards
>> Lahiru
>>
>>>
>>> Regards,
>>> Chathuri
>>>
>>>
>>> On Fri, Jan 17, 2014 at 11:25 AM, Sachith Withana <swsachith@gmail.com>wrote:
>>>
>>>> Thanks Saminda for this informative review.
>>>>
>>>> In the case of the multi-threaded vs Single Threaded, where should we
>>>> have the synchronization enforced?
>>>> To my knowledge, the NewJobWorkers( Getting new Jobs and submitting
>>>> them) and the HangedJobWorkers are accessing the Orchestrator table to
>>>> select the new and hanged jobs.
>>>> Right now, the NewJobworkers are getting all the accepted jobs at once.
>>>> it's not focussed on one experiment.
>>>>
>>>> We need to reflect the changes in the Gfac job Statuses in the
>>>> Orchestrator table as well. So every time the status of a job change
>>>> through the Gfac, it will be accessing the Orchestrator table as well. (
>>>> I've sent an email previously describing the scenario)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Jan 17, 2014 at 10:32 AM, Saminda Wijeratne <samindaw@gmail.com
>>>> > wrote:
>>>>
>>>>> Following are few thoughts I had during my review of the component,
>>>>>
>>>>> *Multi-threaded vs single threaded*
>>>>> If we are going to have multi-threaded job submission the
>>>>> implementation should work on handling race conditions. Essentially
>>>>> JobSubmitter should be able to "lock" an experiment request before
>>>>> continuing processing that request so that other JobSubmitters accessing
>>>>> the experiment requests a the same time would skip it.
>>>>>
>>>>> *Orchestrator service*
>>>>> We might want to think of the possibility in future where we will be
>>>>> having multiple deployments of an Airavata service. This could particularly
>>>>> be true for SciGaP. We may have to think how some of the internal data
>>>>> structures/SPIs should be updated to accomodate such requirements in
future.
>>>>>
>>>>> *Orchestrator Component configurations*
>>>>> I see alot of places where the orchestrator can have configurations.
I
>>>>> think its too early finalize them, but I think we can start refactoring
>>>>> them out perhaps to the airavata-server.properties. I'm also seeing the
>>>>> orchestrator is now hardcoded to use default/admin gateway and username.
I
>>>>> think it should come from the request itself.
>>>>>
>>>>> *Visibility of API functions*
>>>>> I think initialize(), shutdown() and startJobSubmitter() functions
>>>>> should not be part of the API because I don't see a scenario where the
>>>>> gateway developer would be responsible for using them. They serve a more
>>>>> internal purpose of managing the orchestrator component IMO. As Amila
>>>>> pointed out so long ago (wink) functions that do not concern outside
>>>>> parties should not be used as part of the API.
>>>>>
>>>>> *Return values of Orchestrator API*
>>>>> IMO unless it is specifically required to do so I think the functions
>>>>> does not necessarily need to return anything other than throw exceptions
>>>>> when needed. For example the launchExperiment can simply return void
if all
>>>>> is succesful and return an exception if something fails. Handling issues
>>>>> with a try catch is not only simpler but also the explanations are readily
>>>>> available for the user.
>>>>>
>>>>> *Data persisted in registry*
>>>>> ExperimentRequest.getUsername() : I think we should clarify what this
>>>>> username denotes. In current API, in experiment submission we consider
two
>>>>> types of users. Submission user (the user who submits the experiment
to the
>>>>> Airavata Server - this is inferred by the request itself) and the execution
>>>>> user (the user who corelates to the application executions of the gateway
-
>>>>> thus this user can be a different user for different gateway, eg: community
>>>>> user, gateway user).
>>>>> I think we should persist the date/time of the experiment request as
>>>>> well.
>>>>> Also when retrying of API functions in the case of a failure in an
>>>>> previous attempt there should be a way to not to repeat already performed
>>>>> steps or gracefully roleback and redo those required steps as necessary.
>>>>> While such actions could be transparent to the user sometimes it might
make
>>>>> sense to allow user to be notified of success/failure of a retry. However
>>>>> this might mean keeping additional records at the registry level.
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Thanks,
>>>> Sachith Withana
>>>>
>>>>
>>>
>>
>>
>> --
>> System Analyst Programmer
>> PTI Lab
>> Indiana University
>>
>
>

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