Why Does My Node.js MySQL Connection Fail Between Midnight and 2 AM, and How Can I Fix It?

MySQL Connection Issue: "Connection lost: The server closed the connection"

Problem:

When using Node.js with MySQL, a "Connection lost: The server closed the connection" error occurs at specific times (usually between midnight and 2 AM).

Solution:

Follow the below steps to address this issue:

var db_config = {
  host: 'localhost',
    user: 'root',
    password: '',
    database: 'example'
};

var connection;

function handleDisconnect() {
  // Recreate the connection
  connection = mysql.createConnection(db_config);

  connection.connect(function(err) {
    if(err) {
      console.log('error when connecting to db:', err);
      setTimeout(handleDisconnect, 2000); // Delay before reconnecting
    }
  });

  // Handling connection errors
  connection.on('error', function(err) {
    console.log('db error', err);
    if(err.code === 'PROTOCOL_CONNECTION_LOST') {
      handleDisconnect();
    } else {
      throw err;
    }
  });
}

handleDisconnect();

Explanation:

This code snippet creates a new connection to the MySQL server when a disconnect occurs. The setTimeout function introduces a delay to prevent a hot loop, allowing the script to process other requests while reconnecting.

The error handler is configured to handle 'PROTOCOL_CONNECTION_LOST' errors, which typically occur during server restarts. Other errors are re-thrown, providing more detailed information about the issue.

The handleDisconnect() function is called to initiate the error handling and reconnection process.

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