Race condition in isaacs/lockfile

output.txt

Got a lock at 798ms
Got a lock at 800ms
Got a lock at 1794ms
Got a lock at 1794ms
Got a lock at 1795ms
Got a lock at 1796ms
Got a lock at 1797ms
Got a lock at 2794ms
Got a lock at 2795ms
Got a lock at 2796ms
Got a lock at 2797ms
Got a lock at 3794ms
Got a lock at 3794ms
Got a lock at 3795ms
Got a lock at 3795ms
Got a lock at 3795ms

race.js

var lockfile = require('lockfile');

var opts = {stale: 1000};
var startTime = Date.now();
var stopAfter = 5000;

lockfile.lock('test.lock', opts, function (err) {
	if (err) throw err;

	var stop = false;

	function attemptToLock() {
		if (stop) {
			return;
		}

		lockfile.lock('test.lock', opts, function (err) {
			if (err) {
				attemptToLock();
				return;
			}

			console.log("Got a lock at " + (Date.now() - startTime) + "ms");
		});
	}

	setTimeout(function () {stop = true;}, stopAfter);

	for (var i=0; i<16; i++) {
		attemptToLock();
	}
});