Re: A 'horror story' for the books


David Herron -- One of the vertebrae (david@g.ms.uky.edu)
12 Sep 88 22:51:52 GMT


First, thanks to everyone who responded to my posting. The consensus
was that trailers while on the surface seeming like a good thing are,
in practice, somewhat 'bad' and it's not even clear if they actually
help even in their native environment. Plus there are cases (Sun's
especially) where they hurt performance because the idea is too Vax
specific and especially too specific to the Vax memory management.

In article <22891@amdcad.AMD.COM> > rpw3@amdcad.UUCP (Rob Warnock) writes:
>In fact, you should have been able to watch your SMTP mail on a packet
>monitor and seen the entire "HELO", etc., dialog go along just fine up
>to the point that the trailer-using host blasted its first full-sized
>packet at the non-trailer host... whereupon the trailer'd packet would
>be periodically retransmitted until the connection timed out.

Well, being able to watch my SMTP mail on a packet monitor assumes the
presence of a packet monitor in the first place. The closest I have
is tcpdump which, that I know of, does not display the contents of the
packet. (The joys of living in a poor state at a University which isn't
yet fully up to speed on networking technology & hardware ....)

Anyway. What I was seeing from the user level was the SMTP conversation
succeeding up to the point where the program had finished sending
all of the DATA section. Then it went to send the '.' and hung either
in sending the '.' or waiting for the response (depending on the phase
of the moon, I think). Now possibly the DATA section was being buffered
as much as possible, I don't remember the code that well. Certainly it
looked to me (at the time) as if the code were hanging because of a
short packet rather than a long one...

--
<---- David Herron -- One of the MMDF guys		     <david@ms.uky.edu>
<---- ska: David le casse\*'	  {rutgers,uunet}!ukma!david, david@UKMA.BITNET
<----				What does the phrase "Don't work too hard"
<---- have to do with the decline of the american 'work	ethic'?



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