Dropped HTTP Requests
I'm using HAProxy 1.3.15.7 to load-balance three Tomcat instances, and to fork requests for static content to a single Apache instance. I've found that after the initial HTML page is loaded from Tomcat, the browser's subsequent first request for a static image from Apache gets dropped (neither HAProxy nor Apache logs the request, but I can sniff it). The rest of the images after the first load fine. If I create a small, static, test HTML page on Tomcat (making the images come from a different backend), it shows the first image on the page as broken. If I put the exact same HTML page on Apache (no backend switch required), it works fine. I wonder if we have a configuration problem, or perhaps this is a bug in the way HAProxy deals with an HTTP keepalive request that spreads to a second backend? Here is our simple test HTML page: htmlbodyimg src=/header/logo.jpgbrimg src=/header/play_demo.jpg/body/html Both images come from Apache. Again, if we request this HTML from the same backend as the images, it works. If we request this HTML from the Tomcat backend, the request to Apache for logo.jpg gets dropped. Our config follows: global log 127.0.0.1 local0 notice maxconn 4096 chroot /usr/share/haproxy-jail user apache group apache daemon spread-checks 5 defaults log global modehttp option httplog option dontlognull option forwardfor option redispatch retries 3 timeout connect 4s timeout server 20s timeout client 10s timeout http-request 10s frontend all bind :80 acl rp path_beg /rp acl rp_adserving path_beg /rp/javascript.js or path_beg /rp/do/adserving use_backend apache if !rp use_backend tomcat_nosession if rp_adserving default_backend tomcat_session backend apache server LocalApache localhost:81 balance roundrobin option httpchk / stats enable stats hide-version stats uri /hapstat stats realm Haproxy\ Statistics stats authx:xxx stats refresh 5s backend tomcat_session server TomcatA out1:8080 cookie A check slowstart 10s server TomcatB out2:8080 cookie B check slowstart 10s server TomcatC out3:8080 cookie C check slowstart 10s balance roundrobin option httpchk /rp/index.html timeout server 2m cookie JSESSIONID prefix backend tomcat_nosession server TomcatA out1:8080 check slowstart 10s server TomcatB out2:8080 check slowstart 10s server TomcatC out3:8080 check slowstart 10s balance roundrobin option httpchk /rp/index.html
Re: Dropped HTTP Requests
On Fri, Mar 06, 2009 at 04:55:21PM -0500, Timothy Olson wrote: I'm using HAProxy 1.3.15.7 to load-balance three Tomcat instances, and to fork requests for static content to a single Apache instance. I've found that after the initial HTML page is loaded from Tomcat, the browser's subsequent first request for a static image from Apache gets dropped (neither HAProxy nor Apache logs the request, but I can sniff it). The rest of the images after the first load fine. If I create a small, static, test HTML page on Tomcat (making the images come from a different backend), it shows the first image on the page as broken. If I put the exact same HTML page on Apache (no backend switch required), it works fine. I wonder if we have a configuration problem, or perhaps this is a bug in the way HAProxy deals with an HTTP keepalive request that spreads to a second backend? Haproxy does not support HTTP keepalive yet. However it can workaround it using option httpclose, which you should set in your defaults section. What you describe is typically what happens without the option. Regards, Willy
