有的php扩展，加载是有先后顺序的，如果搞错了，会导致扩展无法加载。

1，pdo_sqlsrv是sqlserver扩展，如果在pdo扩展之前加载就会报以下错误

PHP Warning: PHP Startup: Unable to load dynamic library 'pdo_sqlsrv.so' (tried: /usr/lib64/php/modules/pdo_sqlsrv.so (/usr/lib64/php/modules/pdo_sqlsrv.so: cannot open shared object file: No such file or directory), /usr/lib64/php/modules/pdo_sqlsrv.so.so (/usr/lib64/php/modules/pdo_sqlsrv.so.so: undefined symbol: php_pdo_register_driver)) in Unknown on line 0

解决办法：

extension=pdo.so

extension=pdo_sqlsrv.so //放到pdo后面

2，swoole扩展依赖sockets扩展，在sockets扩展之前加载就会报以下错误

PHP Warning: PHP Startup: Unable to load dynamic library 'swoole.so' (tried: /usr/lib64/php/modules/swoole.so (/usr/lib64/php/modules/swoole.so: cannot open shared object file: No such file or directory), /usr/lib64/php/modules/swoole.so.so (/usr/lib64/php/modules/swoole.so.so: undefined symbol: php_sockets_le_socket)) in Unknown on line 0

解决办法：

extension=sockets.so

extension=swoole.so //放到pdo后面

加载完后，重新启动，php-fpm就好