nodejs mysql Error: Connection lost The server closed the connection - mysql

Question

when I use node mysql, an error is appear between 12:00 to 2:00 that the TCP connection is shutdown by the server. This is the full message:
Error: Connection lost: The server closed the connection.
at Protocol.end (/opt/node-v0.10.20-linux-x64/IM/node_modules/mysql/lib/protocol/Protocol.js:73:13)
at Socket.onend (stream.js:79:10)
at Socket.EventEmitter.emit (events.js:117:20)
at _stream_readable.js:920:16
at process._tickCallback (node.js:415:13)
There is the solution. However, after I try by this way, the problem also appear. now I do not know how to do. Does anyone meet this problem?
Here is the way I wrote follow the solution:
var handleKFDisconnect = function() {
kfdb.on('error', function(err) {
if (!err.fatal) {
return;
}
if (err.code !== 'PROTOCOL_CONNECTION_LOST') {
console.log("PROTOCOL_CONNECTION_LOST");
throw err;
}
log.error("The database is error:" + err.stack);
kfdb = mysql.createConnection(kf_config);
console.log("kfid");
console.log(kfdb);
handleKFDisconnect();
});
};
handleKFDisconnect();

Answer 1

Try to use this code to handle server disconnect:
var db_config = {
host: 'localhost',
user: 'root',
password: '',
database: 'example'
};
var connection;
function handleDisconnect() {
connection = mysql.createConnection(db_config); // Recreate the connection, since
// the old one cannot be reused.
connection.connect(function(err) { // The server is either down
if(err) { // or restarting (takes a while sometimes).
console.log('error when connecting to db:', err);
setTimeout(handleDisconnect, 2000); // We introduce a delay before attempting to reconnect,
} // to avoid a hot loop, and to allow our node script to
}); // process asynchronous requests in the meantime.
// If you're also serving http, display a 503 error.
connection.on('error', function(err) {
console.log('db error', err);
if(err.code === 'PROTOCOL_CONNECTION_LOST') { // Connection to the MySQL server is usually
handleDisconnect(); // lost due to either server restart, or a
} else { // connnection idle timeout (the wait_timeout
throw err; // server variable configures this)
}
});
}
handleDisconnect();
In your code i am missing the parts after connection = mysql.createConnection(db_config);

Answer 2

I do not recall my original use case for this mechanism. Nowadays, I cannot think of any valid use case.
Your client should be able to detect when the connection is lost and allow you to re-create the connection. If it important that part of program logic is executed using the same connection, then use transactions.
tl;dr; Do not use this method.
A pragmatic solution is to force MySQL to keep the connection alive:
setInterval(function () {
db.query('SELECT 1');
}, 5000);
I prefer this solution to connection pool and handling disconnect because it does not require to structure your code in a way thats aware of connection presence. Making a query every 5 seconds ensures that the connection will remain alive and PROTOCOL_CONNECTION_LOST does not occur.
Furthermore, this method ensures that you are keeping the same connection alive, as opposed to re-connecting. This is important. Consider what would happen if your script relied on LAST_INSERT_ID() and mysql connection have been reset without you being aware about it?
However, this only ensures that connection time out (wait_timeout and interactive_timeout) does not occur. It will fail, as expected, in all others scenarios. Therefore, make sure to handle other errors.

Answer 3

better solution is to use the pool - it will handle this for you.
const pool = mysql.createPool({
host: 'localhost',
user: '--',
database: '---',
password: '----'
});
// ... later
pool.query('select 1 + 1', (err, rows) => { /* */ });
https://github.com/sidorares/node-mysql2/issues/836

Answer 4

To simulate a dropped connection try
connection.destroy();
More information here: https://github.com/felixge/node-mysql/blob/master/Readme.md#terminating-connections

Answer 5

Creating and destroying the connections in each query maybe complicated, i had some headaches with a server migration when i decided to install MariaDB instead MySQL. For some reason in the file etc/my.cnf the parameter wait_timeout had a default value of 10 sec (it causes that the persistence can't be implemented). Then, the solution was set it in 28800, that's 8 hours. Well, i hope help somebody with this "güevonada"... excuse me for my bad english.