[Spread-users] Slow receiver

Anurag Gupta agupta at yahoo-inc.com
Tue Jan 27 00:33:35 EST 2004

Thanks for your quick response.

Latency of each message is ~200ms. ktracing the spread daemon (we are on
free bsd) led us to multiple sendmsg's failling for each one succeeding. I
think num_try is restricted to 10 in data_link.c thats why it stops after
200ms. When I do a dump from ktrace, I see 10 of these for each successful

 61327 spread   0.000004 RET   select 0
 61327 spread   0.000003 CALL  sendmsg(0x5,0x80b1ae4,0)
 61327 spread   0.000005 RET   sendmsg -1 errno 49 Can't assign requested
 61327 spread   0.000004 CALL  select(0,0,0,0,0x806a824)

Only uncommented lines in spread.conf are:

Spread_Segment {
  client  xxx.xxx.xxx.xxx
  spread-daemon xxx.xxx.xxx.xxx


-----Original Message-----
From: spread-users-admin at lists.spread.org
[mailto:spread-users-admin at lists.spread.org]On Behalf Of Jonathan
Sent: Monday, January 26, 2004 8:54 PM
To: Anurag Gupta
Cc: spread-users
Subject: Re: [Spread-users] Slow receiver


I don't have quite enough information to know what is going on. Generally
the latency of a single message send in Spread should be quite low. On
modern machines, maybe in the neighborhood of a few hundred microseconds
of work plus scheduling delays (switching between client, daemon, back to
client if run on one machine) of anywhere from a few milliseconds to 30

Can you provide us with your spread.conf configuration and some more
information about how much the receiver is lagging (what the delay is) and
the rough computer power? How are you timing the send time vs receive
time? Are they on different machines?

One note, although it isn't necessarily affecting your results,
on most OS's sleeping for 1ms actually sleeps for 10+ms since 10 ms is the
minimum scheduling delay.



On Mon, Jan 26, 2004 at 08:43:27PM -0800, Anurag Gupta wrote:
> Hi,
> I am seeing some unusual delays in getting spread to transfer messages. I
> have a simple flooder sleeping 1 millis after publishing each message
> (message size 100 bytes), and a receiver receiving those messages (no
> processing done). Receiver is lagging behind in receiving the messages
> a bit.
> How do I see where the delay is? Is this expected? Or a result of some
> misconfiguration?
> regards
> -anurag
> _______________________________________________
> Spread-users mailing list
> Spread-users at lists.spread.org
> http://lists.spread.org/mailman/listinfo/spread-users

Jonathan R. Stanton         jonathan at cs.jhu.edu
Dept. of Computer Science
Johns Hopkins University

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