Nginx对WebService分布式支配,ip_hash失效

worker_processes  1;error_log  logs/error.log  info;events {    worker_connections  1024;}http {    include       mime.types;    default_type  application/octet-stream;    sendfile        on;    keepalive_timeout  65;    server {        listen       8777;        server_name  localhost;        access_log  logs/host.access.log;        location / {            root   html;            index  index index.htm;            proxy_redirect off;             proxy_set_header Host $host;             proxy_set_header X-Real-IP $remote_addr;             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;             proxy_pass http://localhost;                    }    }    upstream localhost {        ip_hash;         server 127.0.0.1:18777;         server 127.0.0.1:28777;    }}