Possible bug in nginx or upstream fair module?

[Momchil Ivanov]

Hi,

I am seeing some strange behavior with nginx 0.6.32, 0.6.35 and 0.6.36 with 
upstream fair load balancer and the patches from [1] for statistics. On [2] 
you can see the statistics taken from nginx via the stub status module. The 
bug that I am seeing results in the increase of the values ( everyting above 
1k ), it seems that at some points the counters just go up and I need to 
restart nginx in order to get correct values. I do not have a way to 
reproduce it, it just happens at some point (might be a day, might be a week 
or more after nginx was started).

I am also seeing jumps in the statistics for connections to upstreams (from 
the patches in [2]). The counters for upstreams can be reset with sending HUP 
to nginx, but the counters from stub status not. The increase in these values 
results in nginx marking the upstream as down and "no live upstreams while 
connecting to upstream" in the error log. In the nginx conf I have an 
upstream with 10 php backends using fair in peak mode.

Is it a nginx bug or does it come from the upstream fair module? Is somebody 
else seeing similar issues with/without the fair module?

1: http://marc.info/?l=nginx&m=121476307101755&w=2
2: http://bgrouter.xaxo.eu/~space/graph_image.png

Thanks,
Momchil