[jhb_airlines] Re: Perception of Server Lag

  • From: "Bones" <bones@xxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Fri, 22 Sep 2006 20:02:05 +0100

If your theory is correct then it suggests that the lag we saw on Wednesday
would have been down to your machine <g>..  If true could you say that your
PC had a lot going on at the time?


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Paul
Sent: 22 September 2006 19:18
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] Re: Perception of Server Lag

Ah but it's not just the senders machine which may delay sending the data
but also the recipients delaying processing once it's received.  The only
way to truly check it would be with two adjacent PC's running the same spec.
One clue where the source of the delay stems from is that you controllers
regularly tell us there is no perceptable lag on your scopes.  This supports
the delay in receiving data packets and the processing of the data received
to the image being shown on screen. ASV hogging the bandwidth during refresh
could definitely be one cause, though anything that takes processing away
from FS's core function will also delay the image processing to screen.

So Bones, my undestanding of what Stefan is telling us is different to
yours, I would expect the observers to see the taxiing aircraft at different
times if their systems were differently loaded.  In other words the delay is
in processing to screen not in receiving the data and I can understand this.
It makes sense to delay drawing to the screen if the data received would not
allow for smoothish motion.  It would look odd to have an aircraft flashing
in and out of vision because of data processing not being updated that


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Bones
Sent: 22 September 2006 18:51
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] Re: Perception of Server Lag

I would guess that the person with the slow machine would be the one sending
delayed data.

The only way to check this would be to run a normal session and hope that
two aircraft are sitting on the ground watching arrivals. If an aircraft is
lagging then I guess the two ground observers should see an identical amount
of lag. It would be odd if one saw the aircraft taxi in a minute or so
before the other ground observer.

Obviously the data being sent to controllers is different as I've never
noticed ANY lag on the radar screen.


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Alastair
Sent: 22 September 2006 18:31
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] Re: Perception of Server Lag

As you say, Stefan's reply was very interesting,

One thing I have been wondering about.

Say pilot 'A' has a fast machine, few TSR's running etc. and pilot 'B' has a
slow machine with everything loaded up.

How would pilot A see pilot B and vice versa?

i.e. would the slow machine bring everything else 'down' the way it used to
happen in the MP days (apparently).

Also it gets more complex when pilots C, D, E etc.. join in the local

Perhaps, when things are quite, a little experimenting might help to clarify

I had honestly thought that when we were all using the one server that the
lag would virtually be non existent, but Wednesday night proved the lie to
that. (albeit at the end of the flying session)

Answers on the back of a £5 note.....etc..


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