[hibernate-dev] Re: Pushing indexes through JGroups

[Emmanuel Bernard]

Lukasz,
I have been discussing with Manik on #3 and we think that JBoss  
Cache / Infinispan are probably a better fit than plain JGroups for  
that as all the plumbing will be configured for you.
When you reach this problem, let's revive this discussion.

On  May 25, 2009, at 11:07, Hardy Ferentschik wrote:

> Hi,
>
> I talked with Łukasz about this last wekk. Definitely, #1 and #3.
> #2 I don't like either.
>
> The befefit of #3 would also be that one could drop the requirement of
> having a shared file system (NFS, NAS, ...) #3 should be quite easy to
> implement. Maybe easy to get started with.
>
> --Hardy
>
> On Mon, 25 May 2009 10:55:52 +0200, Emmanuel Bernard <emmanuel at hibernate.org 
> > wrote:
>
>> Hello
>> I am not sure this is where we should go, or at least, it depends.  
>> here are three scenarii
>>
>>
>> #1 JMS replacement
>> If you want to use JGroups as a replacement for the JMS backend,  
>> then I think you should write a jgroups backend. Check  
>> org.hibernate.search.backend.impl.jms
>> In this case all changes are sent via JGroups to a "master". The  
>> master could be voted by the cluster possibly dynamically but  
>> that's not necessary for the first version.
>>
>> #2 apply indexing on all nodes
>> JGroups could send the work queue to all nodes and each node could  
>> apply the change.
>> for various reasons I am not fan of this solution as it creates  
>> overhead in CPU / memory usage and does nto scale very well from a  
>> theoretical PoV.
>>
>> #3 Index copy
>> this is what you are describing, copying the index using JGroups  
>> instead of my file system approach. This might have merits esp as  
>> we could diminish network traffic using multicast but it also  
>> require to rethink the master / slave modus operandi.
>> Today the master copy on a regular basis a clean index to a shared  
>> directory
>> On a regular basis, the slave go and copy the clean index from the  
>> shared directory.
>> In your approach, the master would send changes to the slaves and  
>> slaves would have to apply them "right away" (on their passive  
>> version)
>>
>> I think #1 is more interesting than #3, we probably should start  
>> with that. #3 might be interesting too, thoughts?
>>
>> Emmanuel
>>
>> PS: refactoring is a fact of life, so feel free to do so. Just  
>> don't break public contracts.
>>
>> On  May 21, 2009, at 22:14, Łukasz Moreń wrote:
>>
>>> Hi,
>>>
>>> I have few questions that concern using JGroups to copy index  
>>> files. I think to create sender(for master) and receiver(slave)  
>>> directory providers.
>>> Sender class mainly based on existing FSMasterDirectoryProvider,  
>>> first create local index copy and send later to slave nodes
>>> (or send without copying, but that may cause lower performance?).
>>> To avoid code redundancy it would be good to refactor a little  
>>> FSMasterDirectoryProvider class, so then I can use copying  
>>> functionality in new DirectoryProvider and add sending one; or  
>>> rather I should work around it?
>>>
>>> I do not understand completely how does the multithreading access  
>>> to index file work. Does FileChannel class assure that, when index  
>>> is copied and new Lucene works are pushed?
>
>
>