Stop the process when expire-channels is done

storage/file.js

@@ -418,6 +418,7 @@ module.exports.create = function (
         openFileLimit: conf.openFileLimit || 2048,
     };
     // 0x1ff -> 777
+    var it;
     Fs.mkdir(env.root, 0x1ff, function (err) {
         if (err && err.code !== 'EEXIST') {
             // TODO: somehow return a nice error
@@ -465,9 +466,12 @@ module.exports.create = function (
                 if (!isValidChannelId(channelName)) { return void cb(new Error('EINVAL')); }
                 clearChannel(env, channelName, cb);
             },
+            shutdown: function () {
+                clearInterval(it);
+            }
         });
     });
-    setInterval(function () {
+    it = setInterval(function () {
         flushUnusedChannels(env, function () { });
     }, 5000);
 };