use Nginx as proxy, ajax request get 405 every other request - ajax

Question

I'm using nginx to separate the static and dynamic content,
this is my nginx config:
#user nobody;
worker_processes 1;
#error_log logs/error.log;
error_log /usr/local/var/logs/nginx/error.log notice;
#error_log logs/error.log info;
pid /usr/local/var/logs/nginx/nginx.pid;
events {
worker_connections 1024;
}
http {
include mime.types;
default_type application/octet-stream;
log_format main '$remote_addr:$remote_port - [$request_method] [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" '
'rt=$request_time uct="$upstream_connect_time" uht="$upstream_header_time" urt="$upstream_response_time"';
access_log /usr/local/var/logs/nginx/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
upstream tomcat_backend {
server localhost:8090;
}
server {
listen 9797;
server_name localhost;
server_name_in_redirect off;
access_log /usr/local/var/logs/nginx/test.access.log main;
error_log /usr/local/var/logs/nginx/test-error.access.log debug;
location ~ \.(jpg|png|js|ico|html|gif|css|map)$ {
root /path/to/static;
}
location ^~ /api/ {
access_log /usr/local/var/logs/nginx/nginx-location.access.log main;
error_log /usr/local/var/logs/nginx/nginx-location-error.access.log debug;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-NginX-Proxy true;
proxy_set_header X-Request-Time $msec;
proxy_redirect off;
proxy_set_header Host $host;
proxy_pass http://tomcat_backend;
#proxy_set_header X-Request-Id $request_id;
}
location / {
root /path/to/static;
index index.html;
if (!-e $request_filename) {
rewrite ^/(.*) /index.html last;
}
}
}
include servers/*;
}
sometimes tomcat can get the request and response it correctly, sometimes nginx just return 405 directly, not event forward to tomcat
this is the console of chrome, it always follow that pattern, 405, 401, 405, 401..., it shows 401 is because I input wrong password in purpose, that mean the request has been forward to tomcat:
I found that if I use node.js as backend(just a proxy server), everything is ok, no 405 anymore.

Answer 1

OK, finally I found the reason.
there is another process is monitoring the same port.
but it's wired that two process are using the same port