What is latency?

[Duke of Hazard]

I have a script that fetches information from a hundred website. It
takes a long time because each website takes a second for the server
to respond. Based on suggestions in this newsgroup I have speeded it
up. But why do servers take one second to spit back a small 3 kilobyte
text file. Why isn't it instant? How does voice over IP overcome this
'delay' problem?

[Hans-Werner Hilse]

OT: Re: What is latency?

Hi,

Erwin Moller wrote:

How does voice over IP overcome this 'delay' problem?

[...]
(Why VOIP is fast? I don't know. Maybe it uses UDP instead of TCP/IP.)

It certainly does (all VOIP protocols I know of, most of them using RTP
for speech transport -- note that signalling is a different matter!).
That alone saves you an SYN/ACK roundtrip compared to TCP. But that's
not all. It also usually sets the QOS bits on the IP packets to
"throughput ". Depends on the routing infrastructure if this information
is used, respected or just kept. Also, we talk about (two)
unidirectional channels which are allowed to have some loss. Not even
remotely comparable.

Parallel fetching would indeed be the solution for the problem in
question here. It even doesn't necessarily mean a CPU or memory
overhead when looking at the relative resource consumption over time...

-hwh