terminal.app

Not sure if others have noticed this but the included terminal.app with
mac os x 10.3 seems very slow and laggy. I ssh into my webserver a lot
from my powerbook and when typing sometimes it falls behind and then all
of a sudden catches up. No other clients suffer this behavior so I'm
guessing it's related to some setting on my mac or on terminal.app

Anybody have this issue? How did you fix it or did you switch terminal
programs?

Any advice welcomed!

 

I use terminal.app extensively and spend several hours a day
working over an ssh connection. There are times when I have
experienced the behaviour you describe but have always put it
down to network or remote server problems and can't say I have
seen it any less often from other clients. If it was a problem
with terminal.app you might expect to see the same behaviour
when editing a local file for example, but I never have.

 

I have noticed this on occasion, but since it is intermittent, I suspect
it is more likely either a network problem or a system load problem
rather than a Terminal problem.

 

It's far more likely that this is due to network delays between you and
your web server, or else slowness on the server itself. Have you
noticed any slowdown when working locally?

 

I have experienced this only when remotely connected to work (never
local) so I also assume it is network related, like maybe a message has
been dropped (missed), and until it times out and a retry is done,
everything is stalled.

I am also suspecting that maybe it is related to activities that cause
Terminal.app to do a screen clear. For example, if I am working in Vim
on the remote system, and I execute a shell command, when the shell
command finishes, and Vim repaints the screen, I am more likely to have
the stall. Other terminal windows connected to the same remote host are
still working fine.

Bob Harris

 

This has nothing to do with terminal, but everything to do with ssh.

The ssh program is an encrypted version of rsh. (Similarly, slogin
is an encrypted rlogin.) These programs operate on principles
similar to the telnet protocol. Every time you type a character, it
is sent to the remote system, which echoes the character back to
you. If the network is slow (or if either computer is busy), you
will notice a lag. This is not a big.

You'll notice the same thing with any ssh client on any operating
system. You sometimes also notice it with straight (non-encrypted)
rsh/rlogin/telnet clients, if the network/server is loaded.

Unless you're seeing the same lag when accessing local programs (that
is, not connected to a remote system), I wouldn't worry about this.

-- David

 

Definitely rsh or network related.

These kinds of activities transmit much more data over your link than
you may think. And with every TCP/IP packet being encrypted, any
delays (due to a slow network or a slow computer) will be magnified.

-- David

 

Much, much more than you may think.

Vi (vim) sets the transmission to "raw mode" (at least
it used to do so many years ago). This essentially
translates to one packet (and one TCP ack) per character
transmitted under certain circumstances.

One character of payload, 40 (give or take) bytes of
headers, in a 128 byte packet. Then the ACK into
yet another small packet. That's maybe 256 bytes to
place a character on your screen. If one of those
ACKS gets lost in the network, it may take several seconds
(or sometimes minutes) to force a retransmit.
"Vim" is not a good thing to be running across
a network because of this.

[Obligatory War Story]
Many years ago, I did an X.25 driver for a client.
In this case, they wanted to run X.25 over TCP/IP.
The driver worked fine, but my client then got a
complaint from one user that their networking bills
were outrageous.

It seems that, at the time (maybe still, I dunno),
the carriers in Europe were charging by the packet.
Since each character typed into Vi/Vim was essentially
two packets (one transmit, one recieve- to paint the
character on the screen), those folks using vi/vim
across the network were paying a very high premium!
[End obligatory War Story]

NPL