PHP警告：在MySQL转储到macOS终端后，“MySQL服务器已经消失”

Question

I am using a PHP script from CLI to download remote MySQL databases (gzip) and extract them directly to my MacBook's MySQL 5.7 (not MAMP) server. It works fine, but as a side effect, my PHP apps (MAMP Pro) lose the MySQL connection in the middle of the CLI script with the warning

PHP Warning:  mysqli::__construct(): MySQL server has gone away in ...

This happens after roundabout a dozen databases (can't reproduce the exact amount). While the CLI script is running, the MySQL pane in System Preferences goes from green/running to red/stopped to again green/running after each CLI dump, which first does not conflict with the the PHP apps in the browser. But at some point the PHP apps obviously lose the connection.

I played around with my.cnf and set

[mysqld]
max_allowed_packet=128M
max_connections=1024

or other amounts, but it doesn't seem to change anything.

When I manually stop and start MySQL in System Preferences after the CLI script has finished, the PHP continues to work normal again.

Any ideas?

EDIT:

Thanks so far, but it's still not fixed. So here's the script in principal:

$tmpPath = '/tmp/'

For each of 30 databases with different size:

$dbName = database name

exec('ssh user@server.com "mysqldump --login-path=local --lock-tables=false '.$dbName.' | gzip" > '.$tmpPath.$dbName.'.sql.gz');
exec('gzip -q -dc '.$tmpPath.$dbName.'.sql.gz | mysql -u root -proot '.$dbName)

Like I said, the PHP CLI script in Terminal doesn't complain at all! It's my PHP apps (backend for Angular frontend apps) that somewhere in the middle of the 30 dumps stop working because of the mentioned error.

Answer 1

我有类似的问题，并通过在mysql.conf中添加max_connections = 1024来修复

Answer 2

We had a similar problem, and used this which reconnects if the connection goes away:

<?php

use Exception;
use PDO;
use Our\Package\Common\Config\DbCredentials;

class DbConnectionManager
{
    private $credentials;

    /** @var PDO $connection */
    private $connection;

    /**
     * DbConnectionManager constructor.
     * @param DbCredentials $credentials
     */
    public function __construct(DbCredentials $credentials)
    {
        $this->credentials = $credentials;
        $this->reconnect();
    }

    /**
     * @return PDO
     */
    public function getConnection()
    {
        if (!$this->isConnected()) {
            $this->reconnect();
        }
        return $this->connection;
    }

    /**
     * @return bool
     */
    private function isConnected()
    {
        try {
            return $this->connection->query('SELECT 1 + 1;');
        } catch (Exception $e) {
            return false;
        }
    }

    /**
     *  Reinitialise the connection to MySQL
     */
    private function reconnect()
    {
        $dsn = $this->credentials->getDriver()
            .':host='.$this->credentials->getHost()
            .';port='.$this->credentials->getPort()
            .';dbname='.$this->credentials->getDbName()
        ;
        $connection = new PDO($dsn, $this->credentials->getUser(), $this->credentials->getPassword(), array(
            PDO::ATTR_TIMEOUT => 28800,
            PDO::ATTR_EMULATE_PREPARES => false,
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        ));
        $this->connection = $connection;
    }
}

You can tweak this. The DBCredentials class is just a plain PHP class with getters & setters for driver, hostname, user, password, db name, you could change it to just take arguments as strings if you like.

Answer 3

You can also get these errors if you send a query to the server that is incorrect or too large. If mysqld gets a packet that is too large . or out of order, it assumes that something has gone wrong with the client and closes the connection.

To avoid this problem ,You must ensure that max_allowed_packet is set bigger in the mysqld server than in the client and that all clients uses the same value for max_allowed_packet. And Remember to restart your server after that !!!!

Answer 4

When you create a mysqldump you lock the tables. I think that is the main problem and that is why your applications is getting that error. Use this options:

--lock-tables, -l

Lock all tables before dumping them. The tables are locked with READ
LOCAL to allow concurrent inserts in the case of MyISAM tables. For
transactional tables such as InnoDB and BDB, --single-transaction is
a much better option, because it does not need to lock the tables at
all.

The original answer here:

Run MySQLDump without Locking Tables

And try user some "sleep" between dump commands.