I've set up the Apache (2.4) load-balancer which is working okay. To monitor its performance, I enabled the balancer-manager handler, which shows the status of the balancers.
I noticed a "Load" column, which was not present in version 2.2, with a value that may be negative, but I don't understand its meaning nor I was able to find documentation relative to this.
Can anyone explain the meaning of that value or point me to the right documentation?
I now understood, how the calculation of "Load" works. Here is a I think more simpler example than on the apache documents page.
Let's say we have 3 worker and a configured load factor of 1.
1) Start
a | b | c
--+---+---
0 | 0 | 0
add the load factor of 1 to all workers
a | b | c
--+---+---
1 | 1 | 1
now select the one with highest value --> a and decrease by the sum of the factor of all (=3) - this is the selected worker
a | b | c
---+---+---
-2 | 1 | 1
2) next round, add again 1 to all
a | b | c
---+---+---
-1 | 2 | 2
now select the one with highest value --> b and decrease by the sum of the factor of all (=3) - this is the selected worker
a | b | c
---+----+----
-1 | -1 | 2
3) next round, add again 1
a | b | c
---+----+----
0 | 0 | 3
now select the one with highest value --> c and decrease by the sum of the factor of all (=3) - this is the selected worker
a | b | c
---+----+----
0 | 0 | 0
startover again :)
I hope this helps others.
The Load value is populated by lbstatus based on this line of code:
ap_rprintf(r, "<td>%d</td><td>", worker->s->lbstatus);
in https://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_proxy_balancer.c?view=markup#l1767 (line might changed when the code modified)
Since your method is by request, lbstatus is specified by mod_lbmethod_byrequests which define:
lbstatus is how urgent this worker has to work to fulfill its quota of work.
Details on the algorithm can be found here: https://httpd.apache.org/docs/2.4/mod/mod_lbmethod_byrequests.html
i too want to know to description for others column like BUSY, ELECTED etc.. my LB has BUSY over 100 already.. i though BUSY should not exceed 100 ( as in 100% server busyness or something )
