topic Re: Explanation of waterfall phases in Open Q&A

Explanation of waterfall phases

Yosi_Neuman — Tue, 28 Mar 2023 11:25:38 GMT

Hi guys

Where can we find an explanation on what are each of the waterfall phases?

For example, what is callback stand for?

We have used this link https://varvy.com/performance/navigation-timing-api.html for explanation but there is no callback.

May be there should be an internal one within Dynatrace documentation ?

Yos

Re: Explanation of waterfall phases

joel_stuart — Thu, 23 Mar 2023 11:22:18 GMT

Hi Yos, there's a table you can refer to under the XHR section of the following documentation page: https://www.dynatrace.com/support/help/user-experi...

To answer your question: Callback time is the time between the start time of first callback and the end time of the last callback (that handled the response of the XHR).

Hope that helps.

Joel

Re: Explanation of waterfall phases

Yosi_Neuman — Mon, 15 Jan 2018 05:28:53 GMT

Hi Joel,

Just what I was missing!

Great, thanks a lot.

Yos

Re: Explanation of waterfall phases

jj_woon — Thu, 29 Nov 2018 06:58:21 GMT

Hi,

May I know what is meant by blocking under Phases? Couldn't find it in the given documentation link page.

Regards,

Re: Explanation of waterfall phases

antonio_villarr — Thu, 14 Mar 2019 15:46:49 GMT

Hi,

I have another question regarding one of the phases: Blocking. What is related to? I was investigating a user action (load home page) with a duration of ~ 31 s, and 28 s was related to blocking, and 2.2s to processing. How should I interpret this huge blocking time? Or it means I have to open a ticket with support?

Kind regards,

Antonio V.

Re: Explanation of waterfall phases

gilgi — Sun, 17 Mar 2019 07:08:00 GMT

Hi Antonio,

Browsers are limited in therms of the number of parallel connections they can run against a "host" (for example www.cnn.com). By default the number is for most browsers 8 parallel connections. This means that if your page is calling a specific host a lot of times with, for example, a lot of images, the first 8 will start running and the next one will only start once one of the previous is completed.

To this you should add the fact that there are other limitations that affect these connections processing, such as JS execution for example.

When the browser sees the reference to the required image, it adds the request for it into the queue of requests. BLOCKING is the time it waits in the queue until it is actually starting.

Gil.