HAproxy roundrobin balancing does not appear to be distributing evently

Posted by andrew on Server Fault See other posts from Server Fault or by andrew
Published on 2010-06-14T21:33:46Z Indexed on 2010/06/14 21:43 UTC
Read the original article Hit count: 332

Hello, I know that with loaded servers, roundrobin in HAproxy (1.4.4) does not evenly distribute, but my servers are currently getting NO traffic (test setup), and roundrobin balancing does www1,www1,www1,www1,www1,...www2,www2,www2,...,www1...

I'm verifying this by having the script being run on each server cat /etc/HOSTNAME (slackware). I need to have it switch back and forth each time to test some session stuff (stored in shared memcached) but am having trouble getting it to switch between my two web servers on each request.

global
    log     127.0.0.1 local0 warning
    maxconn     4096
    chroot      /usr/share/haproxy
    pidfile     /var/run/haproxy.pid
    uid     99
    gid     99
    daemon

defaults
    balance     roundrobin
    fullconn    100
    maxconn     4096
    mode        http
    option      dontlognull
    option      http-server-close
    option      forwardfor
    option      redispatch
    retries     3
    timeout     connect 5000
    timeout     client  20000
    timeout     server  60000
    timeout     queue   60000
    stats       enable
    stats       uri /haproxy
    stats       auth ***:***

frontend www *:80
    log     global
    acl     is_upload hdr_dom(host) -i uploads.site.com
    acl     is_api hdr_dom(host) -i api.site.com
    acl     is_dev hdr_dom(host) -i dev.site.com
    acl     is_apidev hdr_dom(host) -i apidev.site.com
    use_backend uploads.site.com if is_upload
    use_backend api.site.com if is_api
    use_backend dev.site.com if is_dev !is_apidev
    default_backend site.com

backend site.com
    option  httpchk HEAD /alive.php HTTP/1.1\r\nHost:site.com
    server  www1 1.1.1.1:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2
    server  www2 1.1.1.2:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2

backend api.site.com
    option  httpchk HEAD /alive.php HTTP/1.1\r\nHost:api.site.com
    server  www1 1.1.1.1:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2
    server  www2 1.1.1.2:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2

backend dev.site.com
    option  httpchk HEAD /alive.php HTTP/1.1\r\nHost:dev.site.com
    server  www1 1.1.1.1:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2
    server  www2 1.1.1.2:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2

backend uploads.site.com
    option  httpchk HEAD /alive.php HTTP/1.1\r\nHost:uploads.site.com
    server  www1 1.1.1.1:8080 weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2
    server  www2 1.1.1.2:8080 backup weight 10 minconn 5 maxconn 25 check inter 2000 rise 2 fall 2

So basically, I have some different back-ends (I've verified the ACLs are working), with the default option "roundrobin" selected. I've tried removing weights, removing the minconn/maxconn/fullconn attributes for all servers (not just the backend I'm testing), tried removing the ACLs, etc. I've been testing on dev.site.com BTW.

Anyone see a reason why I can't get something like www1,www2,www1,www2,...? Also, this is one of my first questions on here, so please let me know if I left anything needed out of my post.

Thanks!

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