Friday, August 30, 2013

And why do we fall, Bruce ? ...

"... So we can learn to pick ourselves up" (From Batman Begins). But it's a good line none the less. Especially when t comes to technology and computers.

I've run into a little problem while running my node.js irrigation control software. Every once in a while I get this:

        throw arguments[1]; // Unhandled 'error' event
Error: getaddrinfo ENOENT
    at errnoException (dns.js:31:11)
    at Object.onanswer [as oncomplete] (dns.js:123:16)

[1]+  Exit 1                  node ./sched.js

While it's very descriptive in it's message (basically the getaddrinfo failed) it really doesn't tell me anything. I have no code file called events.js (part of node.js). So what does it mean? Well at first I couldn't figure it out. I suspected that it was a problem with the connection to the user (I'm using sockets). So I did a search and found vague references to the problem but no real answers. Until I came upon a bug report where support asked one simple question: "Do you have an 'error' listener set up on your connection instance?" (thanks mscdex for that). It was a 'Duh!' moment for me. I listen for a connect and disconnect (and a few other things) but not an error. So I added:

socket.on('error', function(){

    consolelog("Socket error");
    consolelog("Error from " + address.address + ":"                + address.port + "(" + userCount + ")");

    if(userCount < 0) {
        userCount = 0;

So far it hasn't occurred again, which doesn't mean that it won't but I am hopeful. At the moment I am in the middle of setting and relearning how to use Eclipse. I'm making the effort so I can use Eclipse to debug node.js programs as well as some of my embedded stuff. I don't expect that I will totally give up on emacs as I'm always using that but I expect I'll be using Eclipse a lot more with my work so it's best to get adjusted to the environment now.


At 9/08/2013 8:42 AM, Blogger Neil Cherry said...

Well I came home today to another Unhandled event so I can say that it wasn't the where I needed to catch the event (still it should be caught). So that leaves one other spot in my code, the UDP handler. I've added this code:

this.client.on("error", function (err) {
    consolelog("UDP error: " + err);

Hopefully this will resolve this issue.


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