[Spread-users] write(): java.net.SocketException

Shawn Bradford shawnb at mojix.com
Mon Nov 5 17:29:55 EST 2012


John,

We have encountered the errors where spread disconnects consumers that are
not fast enough.  We have written a fair amount of code to handle this
error (including flow control) and recover gracefully.  In this particular
instance the client is only a producing content to be sent on spread and is
not consuming any messages.  It does not join a group and does not consume
any messages.  Does spread ever disconnect a producer for being too bursty?

Your discussion on flow control is quite good and has several concepts that
we have implemented.

We are surprised to see a producer being disconnected from spread.  The
spread daemon and clients are all running locally (localhost) so the socket
connection should only be terminated by an internal process.

Thanks in advance,
##Shawn


On Mon, Nov 5, 2012 at 1:16 PM, John Schultz <jschultz at spreadconcepts.com>wrote:

> A TCP connection reset error typically indicates that the other end of the
> peer connection has already been closed.  In your case, the Spread daemon
> has likely already closed the client connection on which you are trying to
> send.
>
> In Spread, this happens most often when a client isn't reading fast enough
> from the Server.  After a while, the message delivery queue on the daemon
> for that client gets too large and it kills the client connection for using
> too much of its memory resources.
>
> This typically indicates that your sending applications are either (a) too
> bursty, (b) persistently too fast in how they send to the group or your
> receivers are (c) occasionally too slow / unresponsive.  The fact that this
> problem is intermittent hints that the problem is more likely (a) and/or
> (c).
>
> To avoid this issue you need to have application level flow control such
> that your senders can't overwhelm your receivers (if that is compatible
> with your application).
>
> Here's a primer I wrote on application level flow control a long time ago:
>
> http://lists.spread.org/pipermail/spread-users/2002-March/000655.html
>
> Cheers!
>
> -----
> John Lane Schultz
> Spread Concepts LLC
> Phn: 301 830 8100
> Cell: 443 838 2200
>
> On Nov 5, 2012, at 3:03 PM, Shawn Bradford wrote:
>
>
> Hello,
>
> We are currently using spread and have found this error occurring quite
> frequently. Unfortunately there is little information on write() errors to
> be found on the net (many more read() errors).
>
> spread.SpreadException: write(): java.net.SocketException: Connection reset
>
> Would someone be able to describe what would be a potential issue causing
> this?  I am looking for some guidance as to the source of the error (maybe
> from a developer) to assist in debugging the error.
>
> We have tried to write several test apps to replicate the bug but have
> been unsuccessful.  Our system is quite large with many moving parts and it
> is unclear as to what sequence of events are causing the errors.
>
> We are using spread 4.1 on 64 bit centos 5.5.
>
> Thanks in advance,
> ##Shawn
>
> --
> *         Director Software | Mojix Inc.
>   phone : +1.562.221.3474
>   email : shawn.bradford at mojix.com
>   web : www.mojix.com
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