[Spread-users] Random disconnecting of clients by daemon

John Schultz jschultz at spreadconcepts.com
Mon Aug 31 13:09:47 EDT 2009


Spread implements a token ring reliable multicast protocol on top of  
UDP multicast and unicast.

You can read about it in the Spread academic papers.  It is very  
similar to the single ring protocol used in Totem, another group  
communication system.

-----
John Lane Schultz
Spread Concepts LLC
Phn: 301 830 8100
Cell: 443 838 2200

On Aug 31, 2009, at 12:59 PM, Stradling, Joseph W wrote:

John,

Thanks for the info.

All,

Does Spread use a reliable multicast protocol such as PGM or is it
simply using the fundamental multicast protocol.  Sorry for all the
questions, but I'm getting ready to close out a trade study and this
information affects our decision.

-Joe

-----Original Message-----
From: John Schultz [mailto:jschultz at spreadconcepts.com]
Sent: Friday, August 28, 2009 4:31 PM
To: Stradling, Joseph W
Cc: spread-users at lists.spread.org
Subject: Re: [Spread-users] Random disconnecting of clients by daemon

Spread only uses TCP for client-daemon connections when you remotely
connect.

Spread will use multicast within a LAN (e.g. - a multicast domain) if
you configure it to do so.  Between LANs it will use point-to-point UDP.

Cheers!

-----
John Lane Schultz
Spread Concepts LLC
Phn: 301 830 8100
Cell: 443 838 2200

On Aug 28, 2009, at 2:58 PM, Stradling, Joseph W wrote:

Thanks John and Alexey.  I figured it was some sort of buffering issue.
My test was actually a benchmarking test, not typical use.  I wanted to
see how far I could push Spread and so far I have been pleasantly
surprised.

One question about the underlying communications method.  Does spread
actually multicast between daemons, or is it doing TCP.  I read in the
documentation that as a performance feature spread multicasts between
daemons on the same segment, is this correct?  Also, does Spread do TCP
or Multicast between daemons on different segments?

Thanks,

Joe

-----Original Message-----
From: John Schultz [mailto:jschultz at spreadconcepts.com]
Sent: Friday, August 28, 2009 1:39 PM
To: Stradling, Joseph W
Cc: spread-users at lists.spread.org
Subject: Re: [Spread-users] Random disconnecting of clients by daemon

Yes.  You are sending faster than your readers are reading, so buffers
build up on the server until it gets sick of you using too much of its
memory and kicks your connection.

You need to either ensure your readers always process faster than your
writers send or you need to implement some level of flow control.

Cheers!

-----
John Lane Schultz
Spread Concepts LLC
Phn: 301 830 8100
Cell: 443 838 2200

On Aug 28, 2009, at 12:30 PM, Stradling, Joseph W wrote:

Hello all,

I'm running some tests with Spread at a very high throughput rate (71
Mbps) with messages which are 1024 bytes in size.  After running my test
for 20 minutes or so, the daemon will disconnect me ( I Get the return
value CONNECTION_CLOSED, when I call SP_receive() )

Is this a buffer issue?

Joe
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