Fwd: question about state transition

[Gavin Li <ly...@gmail.com>]

+dev and commits

---------- Forwarded message ----------
From: Gavin Li <ly...@gmail.com>
Date: Tue, Mar 3, 2015 at 12:24 AM
Subject: question about state transition
To: user@helix.apache.org, Development@helix.apache.org


Hi,

We have each server handle some partitions, and we use Master Slave model.

We need to do some work when transit from offline to slave, sometimes it
takes long time. So when the server ranked higher in ideal state is up and
doing the work during the transition of offline to slave, the other server
is changed to slave from master.

This is causing some period of time that there's no master at all which is
problematic. Is it possible to bring the other server down when the higher
rank server is transiting from slave to master instead of when transition
from offline to slave?

THanks,
Gavin Li

Re: question about state transition

[kishore g <g....@gmail.com>]

Hi Gavin,

I am not sure if I got your question. What ideal state mode are you using
(AUTO, SEMI AUTO, CUSTOM)?

can you describe the scenario again may be using node ids N1, N2, N3.

thanks,
Kishore G

On Tue, Mar 3, 2015 at 12:40 AM, Gavin Li <ly...@gmail.com> wrote:

> +dev and commits
>
> ---------- Forwarded message ----------
> From: Gavin Li <ly...@gmail.com>
> Date: Tue, Mar 3, 2015 at 12:24 AM
> Subject: question about state transition
> To: user@helix.apache.org, Development@helix.apache.org
>
>
> Hi,
>
> We have each server handle some partitions, and we use Master Slave model.
>
> We need to do some work when transit from offline to slave, sometimes it
> takes long time. So when the server ranked higher in ideal state is up and
> doing the work during the transition of offline to slave, the other server
> is changed to slave from master.
>
> This is causing some period of time that there's no master at all which is
> problematic. Is it possible to bring the other server down when the higher
> rank server is transiting from slave to master instead of when transition
> from offline to slave?
>
> THanks,
> Gavin Li
>

Re: question about state transition

[Zhen Zhang <ne...@gmail.com>]

If I understand correctly, the problem is we are doing the following two
transitions together:
1) old master: MASTER->SLAVE
2) new master: OFFLINE->SLAVE

Considering OFFLINE->SLAVE is a long transition, we will have a long period
without MASTER, which is bad.

Ideally we can first do:
new master: OFFLINE->SLAVE
Once this is done, we do:
old master: MASTER->SLAVE

In this case, the during the long OFFLINE->SLAVE transition, the old master
is still on. I think to achieve this, as Kishore mentioned, we might put a
partition level constraint of 1 and let OFFLINE->SLAVE be of higher
priority than MASTER->SLAVE.

Partition level constraint is supported by 0.6.4:
https://issues.apache.org/jira/browse/HELIX-426

You can refer to an example here:
https://github.com/apache/helix/blob/helix-0.6.x/helix-core/src/test/java/org/apache/helix/integration/TestPartitionLevelTransitionConstraint.java

Thanks,
Jason










On Wed, Mar 4, 2015 at 12:57 PM, kishore g <g....@gmail.com> wrote:

> Hi Gavin,
>
> Here is the mail that describes the solution.
> http://apache.markmail.org/message/alhlibbjmm75gog3
>
> I do see that this was not supported in some 0.6.x, Jason any idea when we
> added the partition constraint support.
>
> Also, if you need upgrade to latest 0.6.x, you need the to re-deploy only
> the controller.
>
> thanks,
> Kishore G
>
> On Tue, Mar 3, 2015 at 1:41 PM, kishore g <g....@gmail.com> wrote:
>
> > Hi Gavin,
> >
> > That should do the trick. What Vlad said is right. There was an email
> > thread that explained this in detail. Let me see if I can find that.
> >
> > thanks,
> > Kishore G
> >
> > On Tue, Mar 3, 2015 at 11:15 AM, Gavin Li <ly...@gmail.com> wrote:
> >
> >> Can I resolve this by state transition priority and constraint?
> >>
> >> On Tue, Mar 3, 2015 at 12:40 AM, Gavin Li <ly...@gmail.com> wrote:
> >>
> >> > +dev and commits
> >> >
> >> > ---------- Forwarded message ----------
> >> > From: Gavin Li <ly...@gmail.com>
> >> > Date: Tue, Mar 3, 2015 at 12:24 AM
> >> > Subject: question about state transition
> >> > To: user@helix.apache.org, Development@helix.apache.org
> >> >
> >> >
> >> > Hi,
> >> >
> >> > We have each server handle some partitions, and we use Master Slave
> >> model.
> >> >
> >> > We need to do some work when transit from offline to slave, sometimes
> it
> >> > takes long time. So when the server ranked higher in ideal state is up
> >> and
> >> > doing the work during the transition of offline to slave, the other
> >> server
> >> > is changed to slave from master.
> >> >
> >> > This is causing some period of time that there's no master at all
> which
> >> is
> >> > problematic. Is it possible to bring the other server down when the
> >> higher
> >> > rank server is transiting from slave to master instead of when
> >> transition
> >> > from offline to slave?
> >> >
> >> > THanks,
> >> > Gavin Li
> >> >
> >> >
> >>
> >
> >
>

Re: question about state transition

[kishore g <g....@gmail.com>]

Hi Gavin,

Here is the mail that describes the solution.
http://apache.markmail.org/message/alhlibbjmm75gog3

I do see that this was not supported in some 0.6.x, Jason any idea when we
added the partition constraint support.

Also, if you need upgrade to latest 0.6.x, you need the to re-deploy only
the controller.

thanks,
Kishore G

On Tue, Mar 3, 2015 at 1:41 PM, kishore g <g....@gmail.com> wrote:

> Hi Gavin,
>
> That should do the trick. What Vlad said is right. There was an email
> thread that explained this in detail. Let me see if I can find that.
>
> thanks,
> Kishore G
>
> On Tue, Mar 3, 2015 at 11:15 AM, Gavin Li <ly...@gmail.com> wrote:
>
>> Can I resolve this by state transition priority and constraint?
>>
>> On Tue, Mar 3, 2015 at 12:40 AM, Gavin Li <ly...@gmail.com> wrote:
>>
>> > +dev and commits
>> >
>> > ---------- Forwarded message ----------
>> > From: Gavin Li <ly...@gmail.com>
>> > Date: Tue, Mar 3, 2015 at 12:24 AM
>> > Subject: question about state transition
>> > To: user@helix.apache.org, Development@helix.apache.org
>> >
>> >
>> > Hi,
>> >
>> > We have each server handle some partitions, and we use Master Slave
>> model.
>> >
>> > We need to do some work when transit from offline to slave, sometimes it
>> > takes long time. So when the server ranked higher in ideal state is up
>> and
>> > doing the work during the transition of offline to slave, the other
>> server
>> > is changed to slave from master.
>> >
>> > This is causing some period of time that there's no master at all which
>> is
>> > problematic. Is it possible to bring the other server down when the
>> higher
>> > rank server is transiting from slave to master instead of when
>> transition
>> > from offline to slave?
>> >
>> > THanks,
>> > Gavin Li
>> >
>> >
>>
>
>

Re: question about state transition

[kishore g <g....@gmail.com>]

Hi Gavin,

That should do the trick. What Vlad said is right. There was an email
thread that explained this in detail. Let me see if I can find that.

thanks,
Kishore G

On Tue, Mar 3, 2015 at 11:15 AM, Gavin Li <ly...@gmail.com> wrote:

> Can I resolve this by state transition priority and constraint?
>
> On Tue, Mar 3, 2015 at 12:40 AM, Gavin Li <ly...@gmail.com> wrote:
>
> > +dev and commits
> >
> > ---------- Forwarded message ----------
> > From: Gavin Li <ly...@gmail.com>
> > Date: Tue, Mar 3, 2015 at 12:24 AM
> > Subject: question about state transition
> > To: user@helix.apache.org, Development@helix.apache.org
> >
> >
> > Hi,
> >
> > We have each server handle some partitions, and we use Master Slave
> model.
> >
> > We need to do some work when transit from offline to slave, sometimes it
> > takes long time. So when the server ranked higher in ideal state is up
> and
> > doing the work during the transition of offline to slave, the other
> server
> > is changed to slave from master.
> >
> > This is causing some period of time that there's no master at all which
> is
> > problematic. Is it possible to bring the other server down when the
> higher
> > rank server is transiting from slave to master instead of when transition
> > from offline to slave?
> >
> > THanks,
> > Gavin Li
> >
> >
>

Re: question about state transition

[Gavin Li <ly...@gmail.com>]

Can I resolve this by state transition priority and constraint?

On Tue, Mar 3, 2015 at 12:40 AM, Gavin Li <ly...@gmail.com> wrote:

> +dev and commits
>
> ---------- Forwarded message ----------
> From: Gavin Li <ly...@gmail.com>
> Date: Tue, Mar 3, 2015 at 12:24 AM
> Subject: question about state transition
> To: user@helix.apache.org, Development@helix.apache.org
>
>
> Hi,
>
> We have each server handle some partitions, and we use Master Slave model.
>
> We need to do some work when transit from offline to slave, sometimes it
> takes long time. So when the server ranked higher in ideal state is up and
> doing the work during the transition of offline to slave, the other server
> is changed to slave from master.
>
> This is causing some period of time that there's no master at all which is
> problematic. Is it possible to bring the other server down when the higher
> rank server is transiting from slave to master instead of when transition
> from offline to slave?
>
> THanks,
> Gavin Li
>
>