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For those of you using HAProxy along with the stats papge (haproxy?stats), how do I interpret this page? There is no decent explanation.

For instance: Which Session column displays the number of currently active connections to the backend? Session or Sessions Rate?

HopelessN00b
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w00t
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    Some links to documentation re. CVS and HTML: http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#stats – Geffrix Dec 12 '14 at 15:53

2 Answers2

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I think what you are confused about is the difference between concurrency and arrival rate.

Concurrency is how many things are going on at a snapshot in time. The Arrival rate is how many new things arrived during a window of time.

For Example:

enter image description here

During the snapshot there were two concurrent events. The arrival rate during that entire second is 5 events, because there were 5 events that started throughout that second. The key relationship to grasp is that a large amount of concurrent connections can come from a high arrival rate and/or long lived connections (see Little's Law).

Kyle Brandt
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Session rate is the number of new sessions per second. Under sessions, cur is the current number of sessions, max is the maximum concurrent sessions, total is the total number of sessions since haproxy was restarted.

JamesRyan
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  • Ok, so I'll keep my eyes on the Session columns. Can you elaborate a bit on Session rate? – w00t Jun 04 '10 at 08:12
  • Session rate is the number of new sessions per second – JamesRyan Jun 04 '10 at 08:59
  • I don't think that a copy/paste is very helpful. – w00t Jun 04 '10 at 11:02
  • If EK's explanations don't help you, I don't know what can help you, because they look pretty clear to me. – Willy Tarreau Jun 04 '10 at 21:08
  • I didn't copy/paste that to a comment, I edited the answer to make it better – JamesRyan Jun 04 '10 at 21:31
  • @Willy of course they look clear to you, you made the app! :) With the copy/paste I meant that it's the same thing as 2 rows before it. Anyway, thanks for the info. – w00t Jun 16 '10 at 09:58
  • but cur sessions and cur session rate are not the same thing – JamesRyan Jun 18 '10 at 13:55
  • @w00t: Late to the party, but think of it this way. You could have a bunch of 20 MS sessions with in a second, say 10 of them with *none overlapping*. If you looked at it during one of them, you would see one current session, if you look at the rate the next second, you would see 10 per second. – Kyle Brandt Dec 30 '11 at 20:50
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    Is max the maximum ever seen for that server? – hortitude Aug 20 '12 at 21:07
  • @hortitude Great question. I believe so because there is a LIMIT value as well. I imagine the Max would get erased with a restart or something. Not sure how it's persisted. – Joshua Pinter Sep 02 '15 at 16:36
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    @hortitude (3 yrs later...) - Yes, that's max rate or max active seen by that server or backend. – w00t Oct 01 '15 at 11:43
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    @Josh Pinter stats get reset with a haproxy restart or reload. – w00t Oct 01 '15 at 11:43