I am writing small node.js server for helping maintaining build machines. It's basically for testers to be able to drop db or restart server remotely. I have some issues with pg connections. Can anybody have an idea why it is not being closed after first request?
var client = new pg.Client(conString);
var server = http.createServer(function (req, res) {
var url = parse(req.url);
if (url.pathname =='/'){
(...)
}else{
var slash_index = url.pathname.indexOf('/',1);
var mand = url.pathname.slice(1,slash_index);
if (mand =='restart'){
res.write('restarting server please wait');
} else if (mand == 'drop-db'){
console.log('drop-db');
client.connect();
console.log('connect');
var query = client.query("select datname from pg_database;", function(err, result) {
if (err) throw err;
console.log('callback');
});
query.on('end', function() {
console.log('close');
client.end();
});
} else{
res.write('unknown mand : '+ mand);
}
res.write('\n');
res.end();
}
}).listen(5337);
So what I get on screen after first request is :
drop-db
connect
callback
close
great but after next request I get only
drop-db
connect
after next one I already get an pg error
what do I do wrong?
Edit : No errors after second mit . Error after third :
events.js:48
throw arguments[1]; // Unhandled 'error' event
^
error: invalid frontend message type 0
at [object Object].<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:412:11)
at [object Object].parseMessage (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:287:17)
at Socket.<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:45:22)
at Socket.emit (events.js:88:20)
at TCP.onread (net.js:347:14)
I think it is related to opening new connection while old is still on.
Edit 2 :
I've checked postgres logs :
after second request :
2012-03-13 09:23:22 EET LOG: invalid length of startup packet
after third request :
2012-03-13 09:24:48 EET FATAL: invalid frontend message type 0
I am writing small node.js server for helping maintaining build machines. It's basically for testers to be able to drop db or restart server remotely. I have some issues with pg connections. Can anybody have an idea why it is not being closed after first request?
var client = new pg.Client(conString);
var server = http.createServer(function (req, res) {
var url = parse(req.url);
if (url.pathname =='/'){
(...)
}else{
var slash_index = url.pathname.indexOf('/',1);
var mand = url.pathname.slice(1,slash_index);
if (mand =='restart'){
res.write('restarting server please wait');
} else if (mand == 'drop-db'){
console.log('drop-db');
client.connect();
console.log('connect');
var query = client.query("select datname from pg_database;", function(err, result) {
if (err) throw err;
console.log('callback');
});
query.on('end', function() {
console.log('close');
client.end();
});
} else{
res.write('unknown mand : '+ mand);
}
res.write('\n');
res.end();
}
}).listen(5337);
So what I get on screen after first request is :
drop-db
connect
callback
close
great but after next request I get only
drop-db
connect
after next one I already get an pg error
what do I do wrong?
Edit : No errors after second mit . Error after third :
events.js:48
throw arguments[1]; // Unhandled 'error' event
^
error: invalid frontend message type 0
at [object Object].<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:412:11)
at [object Object].parseMessage (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:287:17)
at Socket.<anonymous> (/home/wonglik/workspace/server.js/node_modules/pg/lib/connection.js:45:22)
at Socket.emit (events.js:88:20)
at TCP.onread (net.js:347:14)
I think it is related to opening new connection while old is still on.
Edit 2 :
I've checked postgres logs :
after second request :
2012-03-13 09:23:22 EET LOG: invalid length of startup packet
after third request :
2012-03-13 09:24:48 EET FATAL: invalid frontend message type 0
- I already get an pg error -- which error? Do you get any error or warning messages in the postgres logs? – sarnold Commented Mar 13, 2012 at 6:47
- @sarnold I've edited post and added error messages. – wonglik Commented Mar 13, 2012 at 6:51
2 Answers
Reset to default 5It looks like client (pg.Client) is declared outside the scope of a request, this is probably your issue. It's hard to tell from the code snippet, but it looks like you might have issues with scoping and how async callback control flow works in general, e.g. calling res.end() while callbacks are still in the IO queue. This is totally legal with node, just not sure that is your intent.
It is preferred to use pg.connect which returns a client. see https://github./brianc/node-postgres/wiki/pg
var pg = require('pg');
var server = http.createServer(function (req, res) {
var url = parse(req.url);
if (url.pathname =='/'){
(...)
}else{
var slash_index = url.pathname.indexOf('/',1);
var mand = url.pathname.slice(1,slash_index);
if (mand =='restart'){
res.write('restarting server please wait');
} else if (mand == 'drop-db'){
console.log('drop-db');
pg.connect(conString, function(err, client) {
console.log('connect');
var query = client.query("select datname from pg_database;", function(err, result) {
if (err) throw err;
console.log('callback');
});
query.on('end', function() {
console.log('close');
// client.end(); -- not needed, client will return to the pool on drain
});
});
} else{
res.write('unknown mand : '+ mand);
}
// these shouldn't be here either if you plan to write to res from within the pg
// callback
res.write('\n');
res.end();
}
}).listen(5337);
I was getting this error, similar to you, and it was that the connection wasn't closed. When you attempt to (re)connect via an already open connection, things go boom. I would suggest that you use the direct connection stuff, since you don't seem to need the pooling code - might make it easier to trap the problem. (Though, given that I've resurrected an older post, I suspect that you probably already fixed this.)