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From: cak@purdue.ARPA (Christopher A. Kent)
Newsgroups: net.unix-wizards
Subject: Problem with repeated TCP segments in 4.2?
Message-ID: <2334@brl-tgr.ARPA>
Date: Tue, 22-Oct-85 16:40:50 EDT
Article-I.D.: brl-tgr.2334
Posted: Tue Oct 22 16:40:50 1985
Date-Received: Thu, 24-Oct-85 05:51:56 EDT
Sender: news@brl-tgr.ARPA
Lines: 21

I'm developing a system which, among other things, uses the network to
log data to another machine. I noticed that, at times, the log file
grew incredibly quickly when there was little or no actual activity.
The machine running the system also often crashed (with panic: sbflush
2) shortly thereafter. If it didn't crash, I never got new data in the
log stream, just the same block or part of it repeated forever.

I dug into the log files, and discovered that blocks of data were
repeated; these blocks were always an even multiple of 2k (usually 4k
or 8k.) I cast suspicion on my code, on stdio (which I tried to use on
the sockets, but it doesn't really work right), and finally on the TCP.
I discovered that at times I do very large (>30K) writes in one system
call, and wondered if this might be the problem; sure enough, when I
recoded to never write more than 1K/syscall, the problem disappeared.

Has anyone else seen this? Is there a fix somewhere? I don't have the
time or inclination to track it down, but it should be repaired...

Cheers,
chris
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