Need network troubleshooting help

I added some printf for each Alloc and each Free. Starting from the beginning, this is the original JS code:

function sendTemp(temp) {
  var q = url.parse(postUrl + "?temp=" + temp);
  q.method = "POST";
  q.headers = {'Content-Length': 0};
  //console.log("REQ:", q);
  var req = http.request(q, function(resp) {
    resp.on('data', function(d) { if (d !== 'OK') console.log("Got unexpected response:", d); });
    resp.on('close', function(gotErr) {
      if (!gotErr && resp.statusCode !== "200") console.log("Got HTTP code", resp.statusCode);
      if (gotErr || resp.statusCode !== "200") errCnt++; else okCnt++;
    });
    resp.on('error', function(err) { console.log("HTTP response error: ", err.message); });
  });
  req.on('error', function(err) { console.log("HTTP request error: ", err.message); errCnt++; });
  req.on('close', function(gotErr) { console.log("HTTP done"); });
  if (typeof req.end === 'function') {
    req.end();
  } else {
    console.log("OOPS, no end function @"+(okCnt+errCnt));
    //console.log("OOPS, no end function:", req);
    trace(req);
    clearInterval(int1);
    clearInterval(int2);
  }
}

Here is what happens when it crashes (always on the 255th http request!):

OOPS, no end function @254
#359[r2,l1] Object {
  #360[r1,l2] Name String [2 blocks] "__proto__"    #373[r1,l1] ...
 
  #374[r1,l2] Name String [1 blocks] "type"= int 1
  #373[r1,l2] Name String [2 blocks] "#onconnect"    #484[r1,l1] Function {
      #483[r1,l2] Name Param "resp"         undefined
...

Notice how the proto links to #373 and that's occupied by on_connect.