Rapidly insert a large number of records in a RethinkDB database. Noticing failure for large number of inserts.

insert.js

var r = require('rethinkdb');

// Insert this many rows
// 2547 will fail on connection with
// "(libuv) Failed to create kqueue (24)"
var COUNT = 2546;
// Database to use for the test
var DB = 'test'
// Table to use for the test
var TABLE = 'insertTest';
// Connection info
var CONNINFO = {
    host: 'localhost',
    port: 28015
};

// Get a database connection
// Sometimes a connection attempt fails on first try. Why?
// callback is function (err, res)
var connect = function (callback, retries) {
	var MAX = 3;
	retries = retries ? retries : MAX;
	r.connect(CONNINFO, function (err, conn) {
		if (retries <= 0) {
			console.error('Reached max retries. Giving up connecting.');
			return callback(err, conn);
		}
		if (err) {
			return connect(callback, retries - 1);
		}
		callback(null, conn);
	});
};

// Insert a whole bunch
// callback is function (err, iteration)
var insert = function (count, callback) {
	console.time('Insert');
	for (var i = 1; i <= count; i++) {
		(function (i) {
			// Must use new connection due to ~250ms sequential inserts
			// https://github.com/rethinkdb/rethinkdb/issues/520
			connect(function (err, conn) {
				if (err) {
					console.error('Error connecting for insertion #%d', i, err);
					return callback(err, i);
				}

				r.db(DB)
					.table(TABLE)
					.insert({ number: i })
					.run(conn, function (err, res) {
						conn.close();

						if (err) {
							console.error('Error inserting #%d', i, err);
							return callback(err, i);
						}

						callback(null, i);
					});
			});
		})(i);
	}
}

// Insert callback maintains success and fail counts
var inserted = (function() {
	var success = 0;
	var fail = 0;

	// callback is function (success count, fail count)
	return function (err, row, callback) {
		if (err) {
			fail++;
		} else {
			success++;
		}
		console.log('Processed %d of %d rows', success + fail, COUNT);
		if (success + fail == COUNT) {
			callback (success, fail);
		}
	};
})();

// Everything's done. Let's show some stats.
var done = function (success, fail) {
	console.timeEnd('Insert');
	console.log('Attempted %d of %d inserts with %d successes and %d failures.',
	            success + fail, COUNT, success, fail);
}

insert(COUNT, function (err, row) {
	// Don't check err here - pass it through
	inserted(err, row, done);
});