The current environment is LNMP, use jmeter test, concurrent, 300 cycle 5 times, 20% requests will appear a 503 error, see the online information is said, made a number of IP access restrictions (limit_conn), but I again in the configuration file is not set, is big, please help under, thank you very much
Below is nginx configuration file:
/etc/nginx/nginx. Conf:

 # For more information on the configuration, see: 
# * Official English Documentation: http://nginx.org/en/docs/
# * Official the Russian Documentation: http://nginx.org/ru/docs/

The user nginx. 
Worker_processes auto; 
Worker_rlimit_nofile 65535; 
Error_log/var/log/nginx/error log. 
Pid/run/nginx. Pid; 

# the Load dynamic modules. See the/usr/share/doc/nginx/README. Dynamic. 
Include/usr/share/nginx/modules/*. Conf. 

Events {
Worker_connections 20480; 
Use epoll; 
} 

HTTP {
Log_format main '$remote_addr - $remote_user [$time_local] "$request"' 
'$$body_bytes_sent status "$http_referer"' 
'" $http_user_agent "" $http_x_forwarded_for"; 

Access_log/var/log/nginx/access. Log the main; 

Sendfile on; 
Tcp_nopush on; 
Tcp_nodelay on; 
Keepalive_timeout 200; 
Types_hash_max_size 2048; 

Fastcgi_connect_timeout 300; 
Fastcgi_send_timeout 300; 
Fastcgi_read_timeout 300; 

Include/etc/nginx/mime types; 
Default_type application/octet - stream; 

# the Load modular configuration files from the/etc/nginx/conf. D directory. 
# See http://nginx.org/en/docs/ngx_core_module.html#include 
# for more information. 
Include/etc/nginx/conf. D/*. Conf. 

Server {
80 default_server listen; 
Listen [: :] : 80 default_server; 
Server_name _; 
Root/usr/share/nginx/HTML; 

# the Load configuration files for the default server block. 
Include/etc/nginx/default. D/*. Conf. 

The location/{
} 

Error_page 404/404. HTML; 
Location=/40 x. HTML {
} 

error_page 500 502 503 504/50x.html; 
Location=/50 x) HTML {
} 
} 

# Settings for a TLS enabled server. 
# 
# server {
# listen 443 SSL http2 default_server. 
# listen [: :] : 443 SSL http2 default_server. 
# server_name _; 
# root/usr/share/nginx/HTML; 
# 
# ssl_certificate "/etc/pki/nginx/server. The CRT"; 
# ssl_certificate_key "/etc/pki/nginx/private/server. The key". 
# ssl_session_cache Shared: SSL: 1 m; 
# ssl_session_timeout 10 m; 
# ssl_ciphers HIGH:! ANULL:! MD5; 
# ssl_prefer_server_ciphers on; 
# 
# # the Load configuration files for the default server block. 
# include/etc/nginx/default. D/*. Conf. 
# 
# the location/{
#} 
# 
404/404 # error_page. HTML; 
{# location=/40 x. HTML 
#} 
# 
# error_page 504/50, 500, 502, 503 x. HTML; 
# location=/50 x) HTML {
#} 
#} 

} 

The/etc/nginx/conf. D/default. Conf:

 server {
listen 80; 
Server_name 127.0.0.1; 
Error_page 404/404. HTML; 
error_page 500 502 503 504/50x.html; 
# \. PHP dynamic request processing, only for a static resource request from the following location matching and processing 
The location ~ \. {PHP 
Root/WWW/HTML; 
Fastcgi_pass 127.0.0.1:9000; 
# include nginx server is passed to the fastcgi program parameters, PHP by $_SERVER [' parameter name '] available 
The include fastcgi. Conf; 
# define the variable $fastcgi_script_name_new assignment is $fastcgi_script_name variable 
The set $the path_info ""; 
The set $$fastcgi_script_name fastcgi_script_name_new; 
# to judge whether the url is pathinfo form, if have to divide the url into two parts, the index. The pathinfo part of the PHP file after entrance in $the path_info variable, the rest of the part and the $document_root root directory location index. The absolute path to the PHP files in the file system entrance. 

If ($fastcgi_script_name ~ * ^ "(. + \. PHP) (+)/. $") {
The set $fastcgi_script_name_new $1; 
Set the path_info $2; 
} 

# for fastcgi. Conf SCRIPT_FILENAME and SCRIPT_NAME rewrite fastcgi parameters, the purpose is to specify the absolute path to the entry documents in the file system to SCRIPT_FILENAME parameter, let fastcgi know index. The PHP file location, 
Fastcgi_param SCRIPT_FILENAME $$fastcgi_script_name_new document_root; 
Fastcgi_param SCRIPT_NAME $fastcgi_script_name_new; 
# define a new nginx server is passed to the PATH_INFO fastcgi parameters, thinkphp need the index entry documents. After the PHP pathinfo information 
Fastcgi_param the PATH_INFO $the PATH_INFO; 
} 
# used to match the static resource, if rather than a static resource will rewrite, and training in rotation again all the location, a location above the block matching dynamically after processing the request 
The location/{
Root/WWW/HTML; 
The index index. PHP index. HTML index. HTM; 

if (! - e $request_filename) {
Rewrite ^ (. *) $/index. The PHP $1 last; 
} 
} 
}