My node.js doesn't respond without reporting any errors

Question

My node.js doesn't respond without reporting any errors

I wrote http server in node.js, which is a like reverse-proxy for Amazon S3, and deployed it in production environment with Node's Cluster module, nodejitsu/forever and Nginx. It worked very good but one day (today) it stopped responding. I checked node's console.log() outputs and processes but I found nothing strange.

Gist of my code is like:

http.createServer(function(webReq, webRes) {
  http.get(s3Options, function(s3Res) {
    if (s3Res.statusCode == 200) {
      s3Res.on('end', function() {
        webRes.end('Found data on S3');
      });
    } else {
      webRes.end('No data on S3'); 
    }
  }).on('error', function(e) {
    console.log('problem with s3Req: ' + e.message);
  });
}).listen(1337);

Node processes are all alive (2 child workers) without forever's restarting:

# ps x | grep node
31436 ?  Ss  3:43 node /usr/bin/forever -l LOG -o OUT -e ERR -a start server.js
31437 ?  Sl  0:10 node /root/server.js
31440 ?  Sl  1:17 /usr/bin/nodejs /root/server.js
31441 ?  Sl  1:17 /usr/bin/nodejs /root/server.js

Then I doubted too-many-connection stuffs and did "lsof -p PID | wc -l" but the counts were all in good conditions - only dozens.

My node.js experience is only a week or so. Did I miss something important?

node.js