[jbosscache-dev] Re: Non Blocking State Transfer Status (& Integration with JGroups)

[Bela Ban]

Jason T. Greene wrote:
>> BTW, is a *JGroups* streaming API necessary here?  The old AS Farm 
>> service passed arbitrary sized files by sending byte[] chunks via 
>> RpcDispatcher calls. Worked fine. That's not quite what JBC would 
>> need, since FarmService read a chunk from a FileInputStream and 
>> passed it to JGroups; you'd want an OutputStream impl that would pass 
>> a chunk to JGroups when it's internal buffer reached size X.
>
> Their could be an abstraction in JBC that does this, however we are 
> still missing the piece that says this message needs to go across a 
> separate p2p tcp connection. Otherwise state transfer traffic will 
> compete with live standard operations.

I don't think that's a problem, because most traffic in JBC is multicast 
unless I'm mistaken.

Anyway, whether you use a separate channel, or reuse the existing 
channel doesn't matter because at the end of the day, all traffic uses 
the same underlying link to/from the switch. Even if you created a 
separate connnection (like with STREAMING_STATE_TRANSFER, which creates 
a separate TCP connection), this wouldn't make a difference.

> This problem is amplified when we have multiple state transfers going on.
>
> I suppose we could dynamically create a new JGroups channel for this, 
> but it seems like a lot of overhead for a single p2p connection.

Yes, I wouldn't do this

-- 
Bela Ban
Lead JGroups / Clustering Team
JBoss - a division of Red Hat