Dead cursor repro - Node

dead_cursor_node.js

// mongodb 2.6.4, config file

storage:
    dbPath: "/data/db/264"
systemLog:
    destination: file
    path: "/data/db/264/mongodb.log"
processManagement:
    fork: true

// bulk insert a bunch of data into twitter.tweets
use twitter;
var bulk = db.tweets.initializeUnorderedBulkOp(); start = new Date(); for(var i = 0; i < 500000; i++){bulk.insert({"_id" : i, id : new ObjectId()})}; bulk.execute({w:1}); end = new Date(); print(end - start);

// Test app.js - using mongo native 2.0.x driver

var MongoClient = require('mongodb').MongoClient;
var mongoUrl = 'mongodb://localhost/twitter';

MongoClient.connect(mongoUrl, function(err, db) {
  if (err) return console.error(err);

  var collection = db.collection('tweets');
// 200k limit seems to be needed to trigger, lesser limits are OK
  collection.find({}, {"_id" : 0, id : 1}).limit(200000).forEach(function(tweet) {
// note: setting batch size low, like so triggers the dead cursor messages early
// collection.find({}, {"_id" : 0, id : 1}).batchSize(8000).limit(200000).forEach(function(tweet) {
// otherwise it errors when it hits the 4MiB limit (see log lines from mongod later)
    console.log(tweet.id);
  }, function(err) {
    if (err) console.error(err);
    db.close();
  });
}); 

// log lines from the app:

5446942542aa4250a78f4c35
5446942542aa4250a78f4c36
5446942542aa4250a78f4c37
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }
{ [MongoError: cursor is dead] name: 'MongoError', message: 'cursor is dead' }


// log lines from mongod - note reslen
2014-10-21T18:50:32.548+0100 [conn50] query twitter.tweets planSummary: COLLSCAN cursorid:30362014860 ntoreturn:200000 ntoskip:0 nscanned:199728 nscannedObjects:199728 keyUpdates:0 numYields:0 locks(micros) r:120400 nreturned:199728 reslen:4194308 120ms
2014-10-21T18:55:01.597+0100 [conn56] query twitter.tweets planSummary: COLLSCAN cursorid:31266586339 ntoreturn:200000 ntoskip:0 nscanned:199728 nscannedObjects:199728 keyUpdates:0 numYields:0 locks(micros) r:109383 nreturned:199728 reslen:4194308 109ms

// tried with each instead of foreach, hangs now, but at the exact same spot

var MongoClient = require('mongodb').MongoClient;
var mongoUrl = 'mongodb://localhost/twitter';

MongoClient.connect(mongoUrl, function(err, db) {
  if (err) return console.error(err);

  var collection = db.collection('tweets');
  var cursor = collection.find({}, {"_id" : 0, id : 1});
  cursor.limit(200000).each(function(err, docs) {
    console.log(docs.id);
    if (err) console.error(err);
    if (docs == null) {
        db.close();
    };
  });
});

// this time had to Ctrl-C
5446942542aa4250a78f4c35
5446942542aa4250a78f4c36
5446942542aa4250a78f4c37
^C
real	5m15.008s

// monggod logs are the same

2014-10-21T20:00:06.097+0100 [conn87] getmore twitter.tweets cursorid:32151774517 ntoreturn:0 keyUpdates:0 numYields:0 locks(micros) r:113293 nreturned:199728 reslen:4194308 113ms