Solution to 502 bad gateway error in nginx+php-fpm

1, nginx error If the location cannot be found, you generally need to modify /usr/local/nginx/conf/nginx.conf (careful modification may cause other website problems)

2,502 error

Case 1: nginx hangs Dropped:

Command: /usr/local/nginx/sbin/nginx -s reload

and then wait for a while

Case 2: php hung up:

First you need to modify /usr/local You need to keep trying the parameters in the /php-5.6.0/etc/php-fpm.conf file and then use one or more of the following commands to restart the configuration /usr/local/php -5.6.0/sbin/php-fpm reload

/usr/local/php-5.6.0/sbin/php-fpm

/usr/local/php-5.6.0/sbin/php- fpm -h

/usr/local/php-5.6.0/sbin/php-fpm–t

/usr/local/php-5.6.0/sbin/php-fpm–R

Finally restart nginx and wait for a while

If the above method does not work, you can try the following

1. The number of php-fpm processes is not enough

Use netstat -napo |grep "php-fpm" | wc -l Check the current number of fastcgi processes. If the number is close to the upper limit configured in conf, you need to increase the number of processes. But you can’t increase it endlessly. You can adjust the number of php-fpm sub-processes to 100 or more according to the server memory. On a server with 4G memory, 200 is enough. 2. Increase the number of open files in the Linux kernelYou can use these commands (must be a root account)echo 'ulimit -HSn 65536' >> / etc/profileecho 'ulimit -HSn 65536' >> /etc/rc.localsource /etc/profile 3. The script execution time times outIf the script is because For some reason, if there is no return after waiting for a long time, new requests cannot be processed. You can adjust the following configuration appropriately. nginx.conf is mainly as followsfastcgi_connect_timeout 300;fastcgi_send_timeout 300;fastcgi_read_timeout 300;

php-fpm.conf if it is as follows request_terminate_timeout = 10s 4. The cache setting is relatively smallModify or add configuration to nginx.confproxy_buffer_size 64k;proxy_buffers 512k;proxy_busy_buffers_size 128k;

5. recv() failed (104: Connection reset by peer ) while reading response header from upstreamPossible reasons include network packet loss in the computer room or a hardware firewall in the computer room that prohibits access to the domain nameBut the most important thing is to set a timeout in the program and do not use request_terminate_timeout of php-fpm ,It is best to set request_terminate_timeout=0;because this parameter will directly kill the php process and then restart the php process, so the front-end nginx will return 104: Connection reset by peer. This process is very slow, and the overall feeling is that the website is stuck. May 01 10:50:58.044162 [WARNING] [pool www] child 4074, script '/usr/local/nginx/html/quancha/sameip/detail.php' execution timed out (15.129933 sec), terminating May 01 10:50:58.045725 [WARNING] [pool www] child 4074 exited on signal 15 SIGTERM after 90.227060 seconds from startMay 01 10:50:58.046818 [NOTICE] [pool www] child 4082 started

The most important thing is to control the timeout in the program. The timeout period must be set for functions such as gethostbyname, curl, file_get_contents, etc. The other is Duoshuo. This thing increases the interactivity of the website, but the response will be slower if it is used too much. If your website times out and you use Duoshuo, you can turn it off.

The above introduces the solution to the 502 bad gateway error in nginx+php-fpm, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.