[Spread-users] spread delay problem

[John Lane Schultz]

Adrian,

It does sound like there is an issue in your setup for some reason with
getting the leader to give up the token.  Right now, if user traffic is not
being sent, then the token does not circulate continuously to minimize
bandwidth usage.  After some number of circulations with no user caused
sends and no retransmissions requested, then the leader will hold on to the
token and only circulate it periodically (Hurry_timeout) for testing
connectivity.

There is a mechanism by which a non-leader can request token circulation if
it isn't already circulating and they have user data to send.  It could very
well be that this mechanism isn't working in your setup for some reason,
which is what Mike Perik was saying.  Make sure that all your daemons can
send UDP point to point to one another on the configured ports, plus the
following 2 contiguous ports (e.g. - 4800, 4801, 4802).

Here's a tweak that might mask this issue for you.  In protocol.c in the
function To_hold_token() around line 1277, there is a check on the
Token_counter.  Right now it checks if it is greater than 1, then it holds
the token.  This means if the token circulates with no new user msgs and no
retransmissions requested then after 1 such circulation the leader will
swallow it and only send it out again if explicitly requested or when the
Hurry_timeout expires.

You can change the check to a much larger number (e.g. - 10,000).  This
means that the token will continue circulating as fast as possible even when
there doesn't seem to be any activity for X full circulations.  This uses up
bandwidth, but if your system is decently active, then it may fully mask the
issue for you.

If you don't mind the bandwidth of the token always circulating, you could
use a really big number like 2 billion or something.  Then you should only
see this issue if the token really is lost, which will cause a Hurry_timeout
delay.

Cheers!

---
John Lane Schultz
Spread Concepts LLC
Phn: 443 838 2200 

-----Original Message-----
From: Adrian Revill [mailto:adrian.revill at shazamteam.com] 
Sent: Friday, November 07, 2008 9:20 AM
To: John Lane Schultz
Cc: spread-users at lists.spread.org
Subject: Re: [Spread-users] spread delay problem

Hi John,

I have tried the Hurry_timeout at 100ms and the pauses have now gone to 
100ms. To help me tune the value, is there any way i can see the actual 
time it takes for a token to rotate?

An odd thing though, before i tried the lower time-out, i re-ran my 
tests, but forgot to remove the PROTOCOL logging. All the pauses changed 
to approx 300ms. As soon as i turned off the logging, they went back to 2s



John Lane Schultz wrote:
> It definitely sounds like you are losing the token.  You can use spmonitor
> to connect to the daemons and see what kind of losses they have.  You can
> also lower the Hurry_timeout, set at the top of membership.c, to reduce
how
> long the pauses from a loss of token take.  On a LAN you could try
something
> like 10-100ms depending on the size of your configuration (bigger ->
> longer).
>
> Cheers!
>
> ---
> John Lane Schultz
> Spread Concepts LLC
> Phn: 443 838 2200 
> -----Original Message-----
> From: spread-users-bounces at lists.spread.org
> [mailto:spread-users-bounces at lists.spread.org] On Behalf Of Adrian Revill
> Sent: Thursday, November 06, 2008 11:39 AM
> To: spread-users at lists.spread.org
> Subject: [Spread-users] spread delay problem
>
> I found a similar problem to mine on these lists 
> http://lists.spread.org/pipermail/spread-users/2004-December/002367.html
>
> Did anyone ever get a solution?
>
> regards
>
> Adrian
>
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