Javascript 未触发在随机保存之前解析

我正在尝试使用beforeSave触发器为数据对象自动设置ACL。但是，有时，beforeSave方法似乎是随机触发的，即使对象已正确保存

我有一个最小的例子，对于一个或两个对象几乎总是失败的。以下是云代码：

Parse.Cloud.beforeSave("TestObj", function(request, response) {
    if (!request.object.existed()) {
        request.object.setACL(new Parse.ACL(request.user));
    }
    response.success();
});

这里创建了12个用户，每个用户都有一个数据对象（我只是在firefox中本地运行它）：

function initUsers() {
    Parse.initialize("TheApplicationId", "TheClientKey");
    Parse.User.logOut();

    const TestObj = Parse.Object.extend("TestObj", {}, {});
    minimalInitTest([new TestObj(), new TestObj(), new TestObj(), new TestObj(),
        new TestObj(), new TestObj(), new TestObj(), new TestObj(),
        new TestObj(), new TestObj(), new TestObj(), new TestObj()], 0);
}

function minimalInitTest(objs, idx) {
    if (idx < objs.length) {
        var u = new User();
        const email = "test" + idx + "@example.com";
        u.set("username", email);
        u.set("password", "test");
        u.set("email", email);

        u.signUp(null, {
            success: function(user) {
                user.set("data", objs[idx]);
                user.save(null, {
                    success: function(o) {
                        minimalInitTest(objs, idx+1);
                    },
                    error: function(e) { console.error(e); }
                });
            },
            error: function(e) { console.error(e); }
        });
    }
}

I2015-05-28T12:40:26.498Z]v100 before_save triggered for TestObj for user hMX2TQdKlZ:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"hMX2TQdKlZ":{"read":true,"write":true}}}

I2015-05-28T12:40:27.826Z]v100 before_save triggered for TestObj for user k8OTAas7mg:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"k8OTAas7mg":{"read":true,"write":true}}}

I2015-05-28T12:40:28.475Z]v100 before_save triggered for TestObj for user ztrsg7k7Mj:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"ztrsg7k7Mj":{"read":true,"write":true}}}

I2015-05-28T12:40:29.314Z]v100 before_save triggered for TestObj for user CzyjZdmHwm:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"CzyjZdmHwm":{"read":true,"write":true}}}

I2015-05-28T12:40:29.945Z]v100 before_save triggered for TestObj for user Tg6h5VjZ5t:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"Tg6h5VjZ5t":{"read":true,"write":true}}}

I2015-05-28T12:40:30.590Z]v100 before_save triggered for TestObj for user S73xIzKBgL:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"S73xIzKBgL":{"read":true,"write":true}}}

I2015-05-28T12:40:31.365Z]v100 before_save triggered for TestObj for user 0fsea0JDbF:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"0fsea0JDbF":{"read":true,"write":true}}}

I2015-05-28T12:40:32.021Z]v100 before_save triggered for TestObj for user McHukXGAGi:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"McHukXGAGi":{"read":true,"write":true}}}

I2015-05-28T12:40:32.609Z]v100 before_save triggered for TestObj for user ebBQcCV4zi:
  Input: {"original":null,"update":{}}
  Result: Update changed to {"ACL":{"ebBQcCV4zi":{"read":true,"write":true}}}