After nginx starts, start tomcat. tomcat will report an error

Question

After I start nginx first, and then start tomcat, IDEA will prompt as shown in the figure below, and then I cannot access the jsp page.

Then if I start tomcat first, nginx will fail to start when starting nginx. After starting nginx, there is no nginx in the process list

This is my nginx.conf

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


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"';

    log_format  main  ' $remote_user [$time_local]  $http_x_Forwarded_for $remote_addr  $request '  
                      '$http_x_forwarded_for '  
                      '$upstream_addr '  
                      'ups_resp_time: $upstream_response_time '  
                      'request_time: $request_time';  

    access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

    server {
        listen       8081;
        server_name  localhost:8080;

        #charset koi8-r;

        access_log  logs/host.access.log  main;

        location / {
            proxy_pass http://localhost:8080/;
        }

        #location / {
         #   root   html;
         #   index  index.html index.htm;
        #}

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        #location ~ \.php$ {
        #    root           html;
        #    fastcgi_pass   127.0.0.1:9000;
        #    fastcgi_index  index.php;
        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
        #    include        fastcgi_params;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #    deny  all;
        #}
    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename  alias  another.alias;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}


    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}

}

The problem just solved is now encountered another problem
The speed is very slow when accessing nginx8081 and forwarding to tomcat
F12 took a look


#. . The Load page does not start until 40 seconds. The previous ones failed. I don’t know why

Answer 1

If a problem occurs, you should first analyze the reported error instead of asking directly. You must develop analytical and problem-solving abilities. An error like this is already obvious: translated it is port competition, that is, different programs use the same port.

Answer 2

Generally, ports cannot be used by multiple processes. Tomcat uses port 8080, but nginx cannot. In the same way, if nginx is started first, port 8080 has already been occupied, and Tomcat cannot use this port.

The solution is to change nginx to listen to port 80:

server {
        listen       80;
        server_name  localhost;
        ......

You can also change the Tomcat port, but it’s not necessary. If nginx is used as the front end, 80 should be used, and Tomcat is optional.