in reply to Re^2: My first socket program is SLOW?
in thread My first socket program is SLOW?

It's not unbearably slow but it seems to be slower than lynx which is weird to me. Anyway I've been watching the communications with wireshark. I can't find anything that stands out but then again I'm not an expert.

The biggest win will be from fetching things in parallel, so you may be leaving this as an unsolved puzzle...

...in case it's still of interest, apart from the timing of packets the key thing to look at is the Window Size. If the receiver window size is small, then the sender may delay sending packets.

This is what Wireshark shows for a trivial example TCP session:

  No Time     Src  Dest   P Info
   1 00.884 ..130 ..141 TCP ..4 > ..1 [SYN] Seq=0 Len=0 MSS=1460 WS=6
   2 00.884 ..141 ..130 TCP ..1 > ..4 [SYN, ACK] Seq=0 Ack=1 Win=60984 Len=0 MSS=1452 WS=0
   3 00.884 ..130 ..141 TCP ..4 > ..1 [ACK] Seq=1 Ack=1 Win=5888 Len=0
   4 00.892 ..130 ..141 TCP ..4 > ..1 [PSH, ACK] Seq=1 Ack=1 Win=5888 Len=87
   5 00.893 ..130 ..141 TCP ..4 > ..1 [FIN, PSH, ACK] Seq=88 Ack=1 Win=5888 Len=90
   6 00.893 ..141 ..130 TCP ..1 > ..4 [ACK] Seq=1 Ack=179 Win=60807 Len=0
   7 01.000 ..141 ..130 TCP ..1 > ..4 [FIN, ACK] Seq=1 Ack=179 Win=60807 Len=0
   8 01.000 ..130 ..141 TCP ..4 > ..1 [ACK] Seq=179 Ack=2 Win=5888 Len=0
where I've edited the time, IP addresses and port numbers in the interests of conciseness. This shows:

  1. ..130 opening a TCP converstaion with ..141, note the "Window Scaling" WS=6.

  2. ..141 acknowledging the TCP open, returning a "Window Size" of Win=60984 and specifying no "Window Scaling" WS=0.

  3. ..130 completing the TCP open, and returning a "Window Size" of Win=5888 -- which, given ..130's declared scaling of WS=6, means its Window Size is 5888 * 2**6 = 376832 (!)

  4. etc. the rest of the TCP conversation -- noting that all Window Sizes returned by ..130 must be multiplied up by its declared Window Scaling.

The thing to look for is the Window Size being advertised by your machine. If this reduces to something small when using Perl, but not when using Lynx, then that may be the problem. Mind you, these days Window Sizes are pretty big !

The other thing to look for would be your machine being slower to acknowledge stuff when using Perl, or acknowledging smaller amounts each time than when using Lynx.

In Section Seekers of Perl Wisdom