performance - 为什么谷歌浏览器网络中的http请求之间存在差距？

Question

在我的应用程序中，当我加载页面时，很多资源都是从缓存中加载的。但是在 2 个请求之间我得到了一些延迟，如下图所示:

有人可以告诉我为什么我在这两个请求之间有这种延迟(约 300 毫秒)。

Answer 1

差距是花在排队或停滞不前的时间。这可以在下面的示例中演示，该示例显示了四个请求，最后两个是我们的主要关注点:

第三个请求:

第四个请求:

正如您在上面看到的，第 4 个请求中有额外的排队时间以及更多的停顿。这是对此的解释，由 Paul Irish 撰写:

排队:

If a request is queued it indicated that:

• The request was postponed by the rendering engine because it's considered lower priority than critical resources (such as scripts/styles). This often happens with images.

• The request was put on hold to wait for an unavailable TCP socket that's about to free up.

• The request was put on hold because the browser only allows six TCP connections per origin on HTTP 1.

• Time spent making disk cache entries (typically very quick.)

停止/阻塞:

Time the request spent waiting before it could be sent. It can bewaiting for any of the reasons described for Queueing. Additionally,this time is inclusive of any time spent in proxy negotiation.

来源: Understanding Resource Timing