https://www.jb51.net/article/253704.htm
我把mysql的最大连接数由默认的151改成2000了，不知道能不能解决问题。

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Server version: 10.5.22-MariaDB MariaDB Server

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MariaDB [(none)]> show variables like "max_connections";
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 2000  |
+-----------------+-------+
1 row in set (0.001 sec)

PHP错误信息是：
Warning: mysqli_connect(): (HY000/1040): Too many connections in *****