As per various blogs, HAproxy can be gracefully restarted using the following command:

sudo haproxy -f /etc/haproxy/haproxy.cfg -p /var/run/haproxy.pid -sf $(cat /var/run/haproxy.pid)

TO verify this, I had set up a apache bench script which contiguously sent message to haproxy. Ideally, whenever I restarted my server the script should not have an affect on the apache bunch execiton. But, it seems that whenever Haproxy is restarted apache bench scripts terminate and the connection to load balancer is lost.

Here is the details of my HaProxy configuration file :

global
    nbproc 4
    log 127.0.0.1   local0
    log 127.0.0.1   local1 notice
    #log loghost    local0 info
    maxconn 4096
    #chroot /usr/share/haproxy
    user haproxy
    group haproxy
    daemon
    pidfile /var/run/haproxy.pid
    stats socket /home/ubuntu/haproxy.sock
    #debug
    #quiet

    defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
    retries 3
    option redispatch
    maxconn 2000
    contimeout      5000
    clitimeout      50000
    srvtimeout      50000

    listen webstats
    bind 0.0.0.0:1000
    stats enable
    mode http
    stats uri /lb?stats
    stats auth anand:aaaaaaaa
    #stats refresh

    listen web-farm 0.0.0.0:80
         mode http
         balance roundrobin
         option httpchk HEAD /index.php HTTP/1.0
         server server2.com  1.1.1.1:80
         server serve1.com  1.1.1.2:80

~
Please let me know what am I missing here.