MVC输出缓存在1分钟后过期

Question

我为Action设置了一个输出缓存，如下所示。缓存持续时间设置为3600秒，但缓存每分钟刷新一次。任何帮助，将不胜感激。谢谢。

        [OutputCache(Duration = 3600, Location = System.Web.UI.OutputCacheLocation.Any)]
        public ActionResult index()
        {
            var obj = db.tblAdvertisings.GroupBy(c => c.tblCategoryDetail.tblCategory.Category_Information).
                 OrderByDescending(c => c.Count()).
                 Select(c => new AdsCategory
                 {
                     count = c.Count(),
                     category = c.Key,
                     Id = c.FirstOrDefault().tblCategoryDetail.tblCategory.Category_Id,
                     categoryIcon = c.FirstOrDefault().tblCategoryDetail.tblCategory.Category_Icon
                 });
            ViewBag.time = DateTime.Now;
            return View(obj.ToList());
        }