[Spread-users] Re: how to improve Spread performance

Ryan Caudy caudy at jhu.edu
Tue Sep 30 09:06:41 EDT 2003

*Please* keep your replies on the spread-users mailing list.

In general, flow control problems are *not* in the Spread daemon.  You 
didn't really answer my question from before, though.  Do you check 
error messages from SP_* function calls?  If not, please do, and let the 
list know which errors you receive.

What is the structure of your program?  I'd say that many of those on 
the mailing list are familiar with the 2PC and 3PC distributed 
transaction algorithms you said you were implementing via Spread.  The 
question, then, is how you are sending transactions - do you initiate 
many at once and send them in a sliding window, or do you simply handle 
them one at a time?  Do you have transactions initiated at multiple 
machines, concurrently?


Sergio S wrote:

> Hi, my client is an aplication that has to send multicast messages 
> (transactions)to the another machines where is running spread. There is 
> client in each machine and one spread daemon per machine. Randomly, 
> one(or more) of the client is blocked and is not always the same, and 
> the transaction in which it blocks is different each time. I am sure 
> that it is a flow control problem in the spread daemons. What can i do?
> bye
>> From: Ryan Caudy <caudy at jhu.edu>
>> To: Sergio S <brijuerga at hotmail.com>
>> CC: spread-users at lists.spread.org
>> Subject: [Spread-users] Re: how to improve Spread performance
>> Date: Mon, 29 Sep 2003 16:14:05 -0400
>> I'm not sure what you mean by "blocks in one daemon."  Could you 
>> clarify by explaining the program behavior you're seeing in detail?  
>> That is, does your client become disconnected from Spread, or does it 
>> just fail to return from calls to receive, or does something else happen?
>> Sometimes problems of this nature have to do with flow control at the 
>> application level - either it restricts the flow too much, or too 
>> little.  In addition, calls to SP_receive are blocking, but you can 
>> use select or other IO multiplexing tools on the mbox (which is a file 
>> descriptor, really) to get around this.
>> --Ryan
>> Sergio S wrote:
>>> Hi, I am using Spread but I have a problem. I am running an 
>>> aplication that has to run with several spread daemons. One Spread - 
>>> one machine. I have 6 machines.  I am developing a protocol that has 
>>> to send 1000 files of 16 KB. The problem is that when I run the 
>>> aplication occurs that it blocks in one daemon, but the daemon and 
>>> the transaction in which it blocks is random. I am sure the problem 
>>> is in the daemons, but what is the problem? I think it is a problem 
>>> of timeouts or similar.  How can I modify the timeouts? And what 
>>> about  the params Window or Pers Window with spmonitor?
>>> I have the binary distribution. Please answer. Thanks
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>> -- 
>> Ryan W. Caudy
>> Center for Networking and Distributed Systems
>> Department of Computer Science
>> Johns Hopkins University
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>> Spread-users at lists.spread.org
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Ryan W. Caudy
Center for Networking and Distributed Systems
Department of Computer Science
Johns Hopkins University

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