What did option maxconn mean in keyword server? will it cause 503 status?
Hi, all Here is the partial of the haproxy.cfg backend receivers mode http balance roundrobin server s0 172.16.0.202:7700 check maxconn 180 server s1 172.16.0.202:7711 check maxconn 180 I add an option maxconn after keyword server. When haproxy face high volume of requests (about 2 concurrent requests), it return many 503 page: 503 Service Unavailable No server is available to handle this request. Above message is sent by haproxy ( I found this message in ./src/proto_http.c) . why did haproxy send 503 page? I also did not understand the meaning of optioin maxconn. If I remove this option, haproxy will return only very few 503 page. Do option maxconn in above configration mean: if concurrent requests come from frontend is bigger than 180, haproxy will reject these requests and return 503? If the concurrent requests come from frontend is bigger than 180, will haproxy put these requests into a queue? If yes, can I configure the size of the queue? *Additional info* [jj@p2p3 tmp]$ echo show errors | sudo socat stdio /tmp/haproxysock Total events captured on [01/Jul/2014:18:49:29.713] : 0 *Full configuration (haproxy-1.5-dev24)* global log 127.0.0.1 local0 err ulimit-n 50 maxconn 24 nbproc 1 stats socket /tmp/haproxysock defaults log global option log-separate-errors mode http option httplog option dontlognull retries 3 option redispatch contimeout 3000 clitimeout 5 srvtimeout 5 stats uri /haproxy stats enable frontend http_frontend maxconn 24 bind *:80 mode http option forceclose option forwardfor reqrep ^([^\ :]*)\ /(.*) \1\ /receiver/\2 reqadd X-Forwarded-Proto:\ http default_backend receivers backend receivers mode http balance roundrobin server s0 172.16.0.202:7700 check maxconn 180 server s1 172.16.0.202:7711 check maxconn 180 server s2 172.16.0.202:7722 check maxconn 180 server s3 172.16.0.202:7733 check maxconn 180 server s4 172.16.0.202:7744 check maxconn 180 server s5 172.16.0.202:7755 check maxconn 180 谢谢 金杰 (Jie Jin)
RE: What did option maxconn mean in keyword server? will it cause 503 status?
Hi, I add an option maxconn after keyword server. When haproxy face high volume of requests (about 2 concurrent requests), it return many 503 page Of course it will. You would like to serve 2 concurrent requests, but your 6 servers only support 180 concurrent connections each. Do the math: 6 x 180 = 1080 concurrent request can be served in your configuration, of course you will see a lot of 503 errors. why did haproxy send 503 page? Because all backend servers are busy serving 180 concurrent requests, as per your configuration. You have instructed HAProxy not the send more than 180 request per server, and that is exactly what HAProxy is doing (queueing the request until timeout queue [2] expires and then sending 503 errors). I also did not understand the meaning of optioin maxconn. If I remove this option, haproxy will return only very few 503 page. Please read the documentation about maxconn fully [1] then. Do option maxconn in above configration mean: if concurrent requests come from frontend is bigger than 180, haproxy will reject these requests and return 503? It means: each server can handle up to 180 concurrent requests and HAproxy will not send more request to the server, but either use a different server (if there are), or queue it until timeout queue [2] expires, or contimeout as it is in your case (3 seconds). If yes, can I configure the size of the queue? 180 *is* your per server queue size, and its exactly the limitation you are hitting. Additional info [jj@p2p3 tmp]$ echo show errors | sudo socat stdio /tmp/haproxysock Total events captured on [01/Jul/2014:18:49:29.713] : 0 You gonna need to configure the stats socket properly, show errors requires operator or admin privileges on the socket [2] (level admin). Regards, Lukas [1] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#maxconn%20%28Server%20and%20default-server%20options%29 [2] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#timeout%20queue [3] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#9.2-show%20errors
Re: What did option maxconn mean in keyword server? will it cause 503 status?
Hi, Lukas Many thanks , you are awesome. It's my fault that did not read the documentation carefully. I enlarged the timeout queue. No 503 page returned, but the total sessions in frontend accumulated quickly, which means most of the requests are queued by haproxy. I will try to add more servers to run backend server. 谢谢 金杰 (Jie Jin) On Tue, Jul 1, 2014 at 9:50 PM, Lukas Tribus luky...@hotmail.com wrote: Hi, I add an option maxconn after keyword server. When haproxy face high volume of requests (about 2 concurrent requests), it return many 503 page Of course it will. You would like to serve 2 concurrent requests, but your 6 servers only support 180 concurrent connections each. Do the math: 6 x 180 = 1080 concurrent request can be served in your configuration, of course you will see a lot of 503 errors. why did haproxy send 503 page? Because all backend servers are busy serving 180 concurrent requests, as per your configuration. You have instructed HAProxy not the send more than 180 request per server, and that is exactly what HAProxy is doing (queueing the request until timeout queue [2] expires and then sending 503 errors). I also did not understand the meaning of optioin maxconn. If I remove this option, haproxy will return only very few 503 page. Please read the documentation about maxconn fully [1] then. Do option maxconn in above configration mean: if concurrent requests come from frontend is bigger than 180, haproxy will reject these requests and return 503? It means: each server can handle up to 180 concurrent requests and HAproxy will not send more request to the server, but either use a different server (if there are), or queue it until timeout queue [2] expires, or contimeout as it is in your case (3 seconds). If yes, can I configure the size of the queue? 180 *is* your per server queue size, and its exactly the limitation you are hitting. Additional info [jj@p2p3 tmp]$ echo show errors | sudo socat stdio /tmp/haproxysock Total events captured on [01/Jul/2014:18:49:29.713] : 0 You gonna need to configure the stats socket properly, show errors requires operator or admin privileges on the socket [2] (level admin). Regards, Lukas [1] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#maxconn%20%28Server%20and%20default-server%20options%29 [2] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#timeout%20queue [3] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#9.2-show%20errors
