What does the error mean?
{ [Error: Cannot enqueue Query after fatal error.] code: 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR', fatal: false }
This code works in my test file:
function handleDisconnect() {
objConn = mysql.createConnection(db_config); // Recreate the connection, since
// the old one cannot be reused.
objConn.connect(function(err) { // The server is either down
if(err) { // or restarting (takes a while sometimes).
console.log('error when connecting to db:', err.code);
setTimeout(handleDisconnect, 2000); // We introduce a delay before attempting to reconnect,
}else{
console.log('Connected to db!');
} // 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.
objConn.on('error', function(err) {
if(err.code === 'PROTOCOL_CONNECTION_LOST') { // Connection to the MySQL server is usually
handleDisconnect(); // lost due to either server restart, or a
}else{
throw err;
}
});
}
handleDisconnect();
megaLoop();
function megaLoop(){
objConn.query('SELECT u.`email` FROM `users` as u', function(err, rows) {
console.log(err);
console.log(rows);
});
setTimeout(megaLoop, 100);
}
But when I use the function in my Express App I get the error:
{ [Error: Cannot enqueue Query after fatal error.] code: 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR', fatal: false }
Why does it work in my test and not my app?
I had similar issue connecting with MySQL. I solved this issue using connection pool. The concept is to get a connection from a connection pool only when required and release it after use. That way the connection will not be in unstable state. You can get implementation details here.
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