process.domain become undefined after mysql.query(...

[ajostergaard]

Experimenting with v8s new process.domain and noticed that my newly created domain becomes 'undefined' if I do a query:

var d = domain.create();
d.run(function() {
  process.domain.data = {};
  console.log(process.domain); //outputs domain data structure
  mysqlClient = mysql.createConnection(...);
  mysqlClient.connect();
  mysqlClient.query(..., function(...) {
     console.log(process.domain); //outputs 'undefined'
  });
});

(Unless of course I'm doing something completely stupid which is of course entirely possible!)

[dresende]

I tested your example (only without mysqlClient.connect()) and it works fine. What node version are you using?

[ajostergaard]

That's odd.

I tried without connect and makes no difference.

aj$ node -v
v0.8.8

I'll try to reproduce my issue independently of the rest of my code and update here ...

[dresende]

Just to clarify, I'm using node v0.8.12, [email protected]

[ajostergaard]

I was mistaken when I said that .connect made no difference. Actually it works without .connect. :) So the bug is that using the explicit connect method causes subsequent queries to destroy the domain.

[dresende]

It's odd but... I was re-reading this issue and copied your code with [email protected] and it just works. Could you confirm this?

[ajostergaard]

I really don't know/understand what was happening but I've stopped using domains as a result - sorry I can't help further and thanks for taking the time to try to assist.

[jbrumwell]

I'm running into the same problem with [email protected] and mysql@alpha7

console.log(typeof process.domain);
        db.query('SELECT field FROM table WHERE field IN (?)', [ids], function(err, results) {
            console.log(typeof process.domain);
            process.exit();
});

outputs

object
undefined

[dougwilson]

This is just how domains currently work. Even https://github.com/mranney/node_redis and other modules have this issue. It has to do with using callbacks; you need to use domain.intercept:

var d = domain.create();
d.run(function () {
  client.query('...', d.intercept(function (rows) {
    // ... use rows (note, first arguments error was "intercepted" by the domain)
  }));
});

[jbrumwell]

yeah I know that domain#run has that issue and I've been able to get around it by using domain#enter and domain#exit at other portions of the code was trying to avoid wrapping the callbacks. Your solution works thanks for your help doug

[dougwilson]

As of version 2.0.1, process.domain will now be preserved in your callback without you needing to do anything special.