I am running haproxy 1.5.18-3 on CentOS 7 and need to use the stick-table feature to make sure traffic for a specific user persists to a given server.
Things work fine when connections come in slowly, however when there's numerous simultaneous connections and a stick-table entry doesn't exist yet some requests will be sent to both backend servers until they eventually stick to just one. For example, using Apache Bench to test: ab -c 10 -n 30 'http://example.com/index.php?email=a...@example.com' I see this in the haproxy log: May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50812 [08/May/2017:14:49:10.934] http_front backend/server-1 0/0/0/7/7 200 222 - - ---- 9/9/9/4/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50811 [08/May/2017:14:49:10.933] http_front backend/server-2 0/0/0/8/8 200 222 - - ---- 8/8/8/4/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50816 [08/May/2017:14:49:10.935] http_front backend/server-1 0/0/0/7/7 200 222 - - ---- 7/7/7/1/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50819 [08/May/2017:14:49:10.935] http_front backend/server-2 0/0/1/6/7 200 222 - - ---- 6/6/6/1/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50814 [08/May/2017:14:49:10.935] http_front backend/server-1 0/0/0/7/7 200 222 - - ---- 5/5/5/1/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50810 [08/May/2017:14:49:10.933] http_front backend/server-1 0/0/0/9/9 200 222 - - ---- 4/4/4/0/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50813 [08/May/2017:14:49:10.934] http_front backend/server-2 0/0/0/8/8 200 222 - - ---- 3/3/3/0/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50815 [08/May/2017:14:49:10.935] http_front backend/server-2 0/0/0/7/7 200 222 - - ---- 2/2/2/0/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50817 [08/May/2017:14:49:10.935] http_front backend/server-2 0/0/0/7/8 200 222 - - ---- 1/1/1/0/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50818 [08/May/2017:14:49:10.935] http_front backend/server-1 0/0/1/6/8 200 222 - - ---- 0/0/0/0/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50820 [08/May/2017:14:49:10.967] http_front backend/server-1 0/0/0/5/5 200 222 - - ---- 3/3/2/2/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50821 [08/May/2017:14:49:10.968] http_front backend/server-1 0/0/0/4/4 200 222 - - ---- 2/2/2/2/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50823 [08/May/2017:14:49:10.972] http_front backend/server-1 0/0/1/5/6 200 222 - - ---- 7/7/7/7/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" May 8 14:49:10 localhost haproxy[4996]: 1.2.3.4:50822 [08/May/2017:14:49:10.972] http_front backend/server-1 0/0/0/8/8 200 222 - - ---- 6/6/6/6/0 0/0 "GET /index.php?email=a...@example.com HTTP/1.0" [...] After this point haproxy correctly sends all traffic to server-1. When the stick-table entry expires the problem occurs again. I have tried persisting off a url parameter and source address, both exhibit the same issue. Is haproxy unable to properly handle numerous simultaneous (concurrent) requests like this? Is there something I can do to get this to work as desired? Thanks.
