当后端某机器无法连接，或者处理fastcgi请求时异常退出，nginx会将fastcgi请求发送到另外一台机器。

 

配置文件

 

http {    include       mime.types;    default_type  application/octet-stream;    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '    #                  '$status $body_bytes_sent "$http_referer" '    #                  '"$http_user_agent" "$http_x_forwarded_for"';    #access_log  logs/access.log  main;    sendfile        on;    #tcp_nopush     on;    #keepalive_timeout  0;    keepalive_timeout  65;    #gzip  on;        upstream backend {  //配置后端机器                server 192.168.22.103:9000;                server 172.28.250.130:9901;        }    server {        listen       8099;            upstream backend {                server 192.168.22.103:9000;                server 172.28.250.130:9901;                }        .......        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000        #        location ~ \.php$ {            root           html;            fastcgi_pass   backend; //指定到后端机器            fastcgi_index  index.php;            fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;            include        fastcgi_params;        }                ...............

 

2017/10/11 11:12:21 [debug] 24481#0: *66 http upstream request: "/aa.php?"

2017/10/11 11:12:21 [debug] 24481#0: *66 http upstream process header

2017/10/11 11:12:21 [debug] 24481#0: *66 malloc: 0000000006717E30:4096

2017/10/11 11:12:21 [debug] 24481#0: *66 recv: fd:4 0 of 4096

2017/10/11 11:12:21 [error] 24481#0: *66 upstream prematurely closed connection while reading response header from upstream, client: 192.168.22.103, server: localhost, request: "GET /aa.php HTTP/1.1", upstream: "fastcgi://192.168.22.103:9000", host: "172.28.250.184:8099"

2017/10/11 11:12:21 [debug] 24481#0: *66 http next upstream, 2

2017/10/11 11:12:21 [debug] 24481#0: *66 free rr peer 2 4

2017/10/11 11:12:21 [warn] 24481#0: *66 upstream server temporarily disabled while reading response header from upstream, client: 192.168.22.103, server: localhost, request: "GET /aa.php HTTP/1.1", upstream: "fastcgi://192.168.22.103:9000", host: "172.28.250.184:8099"

2017/10/11 11:12:21 [debug] 24481#0: *66 free rr peer failed: 0000000006738850 0

2017/10/11 11:12:21 [debug] 24481#0: *66 close http upstream connection: 4

2017/10/11 11:12:21 [debug] 24481#0: *66 free: 00000000066F71D0, unused: 48

2017/10/11 11:12:21 [debug] 24481#0: *66 event timer del: 4: 1507691601518

2017/10/11 11:12:21 [debug] 24481#0: *66 reusable connection: 0

2017/10/11 11:12:21 [debug] 24481#0: *66 get rr peer, try: 1

2017/10/11 11:12:21 [debug] 24481#0: *66 get rr peer, current: 00000000067388F8 0

2017/10/11 11:12:21 [debug] 24481#0: *66 stream socket 4

2017/10/11 11:12:21 [debug] 24481#0: *66 epoll add connection: fd:4 ev:80000005

2017/10/11 11:12:21 [debug] 24481#0: *66 connect to 172.28.250.130:9901, fd:4 #68

2017/10/11 11:12:21 [debug] 24481#0: *66 http upstream connect: -2

2017/10/11 11:12:21 [debug] 24481#0: *66 posix_memalign: 00000000066F71D0:128 @16

2017/10/11 11:12:21 [debug] 24481#0: *66 event timer add: 4: 60000:1507691601519

2017/10/11 11:12:21 [debug] 24481#0: epoll: stale event 00002AD1E49F92B0

2017/10/11 11:12:21 [debug] 24481#0: timer delta: 1

2017/10/11 11:12:21 [debug] 24481#0: worker cycle

2017/10/11 11:12:21 [debug] 24481#0: epoll timer: 60000

2017/10/11 11:12:21 [debug] 24481#0: epoll: fd:4 ev:0019 d:00002AD1E49F92B1

2017/10/11 11:12:21 [debug] 24481#0: epoll_wait() error on fd:4 ev:0019

2017/10/11 11:12:21 [debug] 24481#0: *66 http upstream request: "/aa.php?"

2017/10/11 11:12:21 [debug] 24481#0: *66 http upstream process header

2017/10/11 11:12:21 [error] 24481#0: *66 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.22.103, server: localhost, request: "GET /aa.php HTTP/1.1", upstream: "fastcgi://172.28.250.130:9901", host: "172.28.250.184:8099"

2017/10/11 11:12:21 [debug] 24481#0: *66 http next upstream, 2

2017/10/11 11:12:21 [debug] 24481#0: *66 free rr peer 1 4

2017/10/11 11:12:21 [warn] 24481#0: *66 upstream server temporarily disabled while connecting to upstream, client: 192.168.22.103, server: localhost, request: "GET /aa.php HTTP/1.1", upstream: "fastcgi://172.28.250.130:9901", host: "172.28.250.184:8099"

2017/10/11 11:12:21 [debug] 24481#0: *66 free rr peer failed: 00000000067388F8 0

2017/10/11 11:12:21 [debug] 24481#0: *66 finalize http upstream request: 502

2017/10/11 11:12:21 [debug] 24481#0: *66 finalize http fastcgi request

2017/10/11 11:12:21 [debug] 24481#0: *66 close http upstream connection: 4

2017/10/11 11:12:21 [debug] 24481#0: *66 free: 00000000066F71D0, unused: 48

2017/10/11 11:12:21 [debug] 24481#0: *66 event timer del: 4: 1507691601519

2017/10/11 11:12:21 [debug] 24481#0: *66 reusable connection: 0

2017/10/11 11:12:21 [debug] 24481#0: *66 http finalize request: 502, "/aa.php?" a:1, c:1

2017/10/11 11:12:21 [debug] 24481#0: *66 http special response: 502, "/aa.php?"

2017/10/11 11:12:21 [debug] 24481#0: *66 internal redirect: "/50x.html?"