Re: Clustering (long)

hmm... hmmm... :-) more thoughts on (1) and (2)... When a node leaves/joins it needs to acquire a lease on the bucket tables of every node that it intends to move buckets from/to. If two nodes are doing this at the same time, their requirement will collide (deadlock) somewhere in the

Re: Clustering (long)

You can define an order to the semaphores when locking and thereby avoid a deadlock. If each node being added or terminating itself honors the order then you will never have a deadlock. However, you still need to deal with the case of an uncontrolled failure either adding or removing a note

Re: Clustering (long)

Joe Bohn wrote: You can define an order to the semaphores when locking and thereby avoid a deadlock. Good idea - If I order the nodes according to some unique id and try for the lease on their bucket table in the same order, then multiple nodes trying at the same time should not deadlock...

Re: Clustering (long)

Hi Jules At 05:37 AM 7/27/2005, Jules Gosnell wrote: I agree on the SPoF thing - but I think you misunderstand my Coordinator arch. I do not have a single static Coordinator node, but a dynamic Coordinator role, into which a node may be elected. Thus every node is a potential Coordinator. If

Re: Clustering (long)

Andy Piper wrote: Hi Jules At 05:37 AM 7/27/2005, Jules Gosnell wrote: I agree on the SPoF thing - but I think you misunderstand my Coordinator arch. I do not have a single static Coordinator node, but a dynamic Coordinator role, into which a node may be elected. Thus every node is a

Re: Clustering (long)

I've had a look at the Lampson paper, but didn't take it all in on the first pass - I think it will need some serious concentration. The Paxos algorithm looks interesting, I will definitely pursue this avenue. I've also given a little thought to exactly why I need a Coordinator and how Paxos

Re: Clustering (long)

hmmm... now I'm wondering about my solutions to (1) and (2) - if more than one node tries to join or leave at the same time I may be in trouble - so it may be safer to go straight to (3) for all cases... more thought needed :-) Jules Jules Gosnell wrote: I've had a look at the Lampson

Re: Clustering (long)

Andy Piper wrote: Hi Jules It sounds like you've been working hard! yes - I need a break :-) I think you might find you run into reliability issues with a singleton coordinator. This is one of those well known Hard Problems and for session replication its not really necessary. In

Re: Clustering (long)

Hi Jules It sounds like you've been working hard! I think you might find you run into reliability issues with a singleton coordinator. This is one of those well known Hard Problems and for session replication its not really necessary. In essence the coordinator is a single point of failure

Re: Clustering (long)

Dain Sundstrom wrote: This is cool stuff and an excellent intro to your code (you should put this summary on your website :) I suggest you start chatting with OpenEJB and ActiveMQ about a shared session key sooner rather then later as it could take a wile to get it into their code bases.

Re: Clustering (long)

This is cool stuff and an excellent intro to your code (you should put this summary on your website :) I suggest you start chatting with OpenEJB and ActiveMQ about a shared session key sooner rather then later as it could take a wile to get it into their code bases. I can't wait to see

Clustering (long)

Guys, I thought that it was high time that I brought you up to date with my efforts in building a clustering layer for Geronimo. The project, wadi.codehaus.org, started as an effort to build a scalable clustered HttpSession implementation, but in doing this, I have built components that should

Re: Clustering (long)

Jules, This is awesome stuff. I look forward to playing with this stuff in Geronimo. Let me know if you need a hand with something... Jeff Jules Gosnell wrote: Guys, I thought that it was high time that I brought you up to date with my efforts in building a clustering layer for Geronimo.

Re: Clustering (long)

Jeff Genender wrote: Jules, This is awesome stuff. I look forward to playing with this stuff in Geronimo. Let me know if you need a hand with something... Thanks for the encouragement, Jeff. It was good to meet you at J1. I'll give you a shout when things get a little more organised.