Hi Gustavo, My implementation for the Phi-Accrual is based on the Cassandra's failure detector, which in turn is based on the ED FD, that is an extension of the original Phi-Accrual paper. The ED FD states that an exponential distribution fits the ping inter-arrival sampling window better than a normal one. Indeed, I have done some experiments that confirms that changes on the Phi parameter make a greater impact on the average detection time when using the exponential distribution.
Regarding the C client, I have already opened a jira ( https://issues.apache.org/jira/browse/ZOOKEEPER-848) for that. I plan to start working on this asap. On Wed, Nov 24, 2010 at 6:43 AM, Flavio Junqueira <[email protected]> wrote: > True, the jira refers to Cassandra. I think Abmar has just experimented > with it, but it is certainly best if he clarifies it. > > On the C client, that's a very good point. In one of my reviews I pointed > it out, but I couldn't find another comment talking about it. I'm not aware > of anyone working on it. We should create a sub-task for it and Abmar could > perhaps clarify if he is planning on producing a patch for the C client. > > Please feel free to add to the jira so that we keep it documented, Gustavo. > > -Flavio > > On Nov 24, 2010, at 10:26 AM, Gustavo Niemeyer wrote: > > Hi Gustavo, I don't know if Abmar was using Cassandra as reference > > (it doesn't sound like from the jira comments), but I followed the paper. > > Feel free to double-check it if you have a chance. > > > The description references Cassandra explicitly, which is why I > wondered. But then, his comments down the JIRA mention normal vs. > exponential distribution, which means he must certainly be aware of > the subtleties. > > Also, note that it won't replace the current mechanism with phi accrual, > but it will enable the use of phi accrual. > > > I'd certainly like to experiment with it at some point. Phi enables > the distinction between "slowing down" and "most likely broken", which > is an interesting feature. It isn't clear from the JIRA if someone is > working on the C client, though. Do you know if there's any > conversation regarding this? > > -- > Gustavo Niemeyer > http://niemeyer.net > http://niemeyer.net/blog > http://niemeyer.net/twitter > > > *flavio* > *junqueira* > > research scientist > > [email protected] > direct +34 93-183-8828 > > avinguda diagonal 177, 8th floor, barcelona, 08018, es > phone (408) 349 3300 fax (408) 349 3301 > > > -- Abmar Barros MSc candidate on Computer Science at Federal University of Campina Grande - www.ufcg.edu.br OurGrid Team Member - www.ourgrid.org Paraíba - Brazil
<<pastedGraphic.tiff>>
