helix-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Krishnamoorthy, Venkata" <Venkata.Krishnamoor...@rbccm.com>
Subject RE: Fencing
Date Wed, 30 Jul 2014 20:44:42 GMT
Hi kanak,

Implementing a custom logic to restart the process was what I was implicitly refering to.

Thanks,
Venkat

________________________________
From: Kanak Biscuitwala [mailto:kanak.b@hotmail.com]
Sent: 2014, July, 30 4:42 PM
To: user@helix.apache.org
Subject: RE: Fencing


Hi Venkata,


It can, but you should know that disabling an instance simply triggers a transition to the
initial state in your state model. Within that transition callback, you need to release locks
or anything else that you would need to do in your system. This doesn't force a restart of
your process or anything like that unless you explicitly implement that logic in your callback.


Kanak
________________________________
From: Venkata.Krishnamoorthy@rbccm.com
To: user@helix.apache.org
Subject: RE: Fencing
Date: Wed, 30 Jul 2014 20:37:22 +0000

I think your response in this mail thread works for this use case:

http://mail-archives.apache.org/mod_mbox/helix-user/201308.mbox/browser

Thanks,
Venkat

________________________________
From: Krishnamoorthy, Venkata
Sent: 2014, July, 29 4:34 PM
To: user@helix.apache.org
Subject: RE: Fencing

Hi Kishore,

Sorry abt the late response. The usecase is as follows:

If multiple replicas of a partition has access to a common resource such as coherence cache
or a databaseassuming that some kind of locking is required at the application level to do
write update, if one of the replicas becomes offline from the point of Helix, then the particular
replica needs to be forcibly restarted to avoid starvation for other replicas.

I was wondering if this requirement can be achieved through Fencing concept using Helix.

Thanks,
Venkat
________________________________
From: kishore g [mailto:g.kishore@gmail.com]
Sent: 2014, July, 24 3:24 PM
To: user@helix.apache.org
Subject: Re: Fencing

Hi Venkat,

We don't have explicit support for fencing. We provide some callbacks that can be used to
deal with such scenarios. Can you give us more info on the scenario. What state model are
you using, what is the shared resource and when you say unresponsive what could be the likely
cause(e.g. GC).

thanks,
Kishore G


On Thu, Jul 24, 2014 at 9:57 AM, Krishnamoorthy, Venkata <Venkata.Krishnamoorthy@rbccm.com<mailto:Venkata.Krishnamoorthy@rbccm.com>>
wrote:
Is there support for Fencing ( http://en.wikipedia.org/wiki/Fencing_(computing)<http://en.wikipedia.org/wiki/Fencing_%28computing%29>
) in Helix? If not, how do I implement this feature to make sure that a participant that is
not responsive is actually shutdown in order to avoid wrongful access to shared resources
and race conditions? Please let me know.

Thanks,
Venkat



________________________________________
This E-Mail (including any attachments) may contain privileged or confidential information.
 It is intended only for the addressee(s) indicated above.
The sender does not waive any of its rights, privileges or other protections respecting this
information.
Any distribution, copying or other use of this E-Mail or the information it contains, by other
than an intended recipient, is not sanctioned and is prohibited.
If you received this E-Mail in error, please delete it and advise the sender (by return E-Mail
or otherwise) immediately.
This E-Mail (including any attachments) has been scanned for viruses.
It is believed to be free of any virus or other defect that might affect any computer system
into which it is received and opened.
However, it is the responsibility of the recipient to ensure that it is virus free.
The sender accepts no responsibility for any loss or damage arising in any way from its use.
E-Mail received by or sent from RBC Capital Markets is subject to review by Supervisory personnel.
Such communications are retained and may be produced to regulatory authorities or others with
legal rights to the information.
IRS CIRCULAR 230 NOTICE:  TO COMPLY WITH U.S. TREASURY REGULATIONS, WE ADVISE YOU THAT ANY
U.S. FEDERAL TAX ADVICE INCLUDED IN THIS COMMUNICATION IS NOT INTENDED OR WRITTEN TO BE USED,
AND CANNOT BE USED, TO AVOID ANY U.S. FEDERAL TAX PENALTIES OR TO PROMOTE, MARKET, OR RECOMMEND
TO ANOTHER PARTY ANY TRANSACTION OR MATTER.


Mime
View raw message