Well, I'm not sure if it is on replication, but I'm sure it happens
whenever I let my cluster nodes see each other.. You see, the replication
configuration is always on, I just let my nodes see the others when I bind
the multicast to the correct interface, and "block" that view when I let
the interface unbound.
I'm thinking of two possibilities here:
1 - if there are no other [known] cluster nodes, the replication code
doesn't even runs. If there are, the replication code runs and (maybe in
my particular app) it gives us a great penalty. So this could be a problem
of a higher level module, not a jgroups problem.
2 - The replication code *always* runs, whenever there are cluster nodes
or not. If so, the penalty could be explained by a overhead of jgroups
semantics (jointly with the higher level replication module) that would
ask every known node to ack that the replicated session has been received.
I think I'll not be able to run any more tests. My thesis has reached its
time limit and my cluster machines are being "recicled" for other
students.. I'll try to reproduce the cluster setuo elsewere.
Thanks. Hope this feedback helps.
--
Joao Pedro Clemente
On Mon, 29 Sep 2003, Bela Ban wrote:
> It would help if you had perf numbers to see where exactly the time is
> spent (i.e., elapsed time, *not* CPU time).
> Are you sure this is on the replication part ?
>
> Joao Clemente wrote:
>
> >Jetty and EJB. Both use javagroups, as far as I know.
> >(Well, the app I'm benchamarking uses both http and ejb sessions. I dunno if
> >the slowdown is seen in both levels or only one, as I only measure the
> >client percieved time)
> >If it is async by default, what could explain the slowdown? I've seen as
> >little as 2x and as much as 10x worse reply time with 2 nodes than I see
> >with 1 node...
> >This was measured with 10 clients / minute = 1/6 req /sec.
> >Using Jboss 3.0.8 + Jetty, jetty replication enabled, multicast messages
> >bound to ethernet interface as I'm using a LVS-DR balancing for wich I had
> >to configure a loopback adapter. And using Windows 2000 with j2sdk 1.4.1_01
> >
> >----- Original Message -----
> >From: "Bela Ban" <[EMAIL PROTECTED]>
> >To: <[EMAIL PROTECTED]>
> >Sent: Thursday, September 25, 2003 1:15 AM
> >Subject: Re: [JBoss-user] Async replication messages possible?
> >
> >
> >
> >
> >>Which repl are you referring to ?
> >>
> >>Session (Tomcat, Jetty) ?
> >>EJBs ?
> >>
> >>I think replis async by default.
> >>
> >>
> >>Joao Clemente wrote:
> >>
> >>
> >>
> >>>Hi.
> >>>(This message is in particular for Bela, but others feedback is welcome)
> >>>
> >>>I'm running some tests and even with a very low request rate (5 req /
> >>>
> >>>
> >minute
> >
> >
> >>>= 1 request / 12 sec) I'm seeing my respose times getting worse by 2 to 5
> >>>times as soon as I let a second node join the cluster. I am assuming it's
> >>>because of a overhead of Jgroups "ack'ing" the replication before letting
> >>>the master node reply to the user.
> >>>(question for bela) Can it be?
> >>>If so, can I put jgroups in "async" mode, either delaying the replication
> >>>message or not waiting for the "ack" from replicas?
> >>>
> >>>Thank you
> >>>Joao Clemente
> >>>
> >>>
> >>>---
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> >>--
> >>Bela Ban
> >>http://www.jgroups.org
> >>Cell: (408) 316-4459
> >>
> >>
> >>
> >>
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> --
> Bela Ban
> http://www.jgroups.org
> Cell: (408) 316-4459
>
>
>
>
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