[Network tab] Can't compute latency time

[sylvain...@gmail.com]

Hi all, 

I'm in a deep trouble toda

[sylvain...@gmail.com]

Sorry for the previous post ...

So, I have timings issues with the network tab of the chrome developper tools. When I inpect a request, sometimes the "latency" time is not equal to the sum of times except receiving. But it's seems to me it should ! Even in the google help page (https://developers.google.com/chrome-developer-tools/docs/network#timeline_view), find the screenshot that shows what happens if you put your cursor on a timeline : it shows detailed times (proxy=0, sending=0, waiting=639ms, Receiving=1ms) but the shown latency is 641ms ! I expect to find 639ms, don't you ?

Do anybody knows how to find part of latency time ?

Thank you for your help

Best regards

Sylvain

[Eugene Klyuchnikov]

Hello.

 Lets take a look at real example.

Timing: 

  connectEnd = connectStart = dnsEnd = dnsStart =  sslEnd = sslStart: -1

  proxyEnd: 1.895

  proxyStart: 1.453

  receiveHeadersEnd: 64.941

  requestTime: 1377263395.6937752

  sendEnd: 2.329

  sendStart: 2.163

Latency is receiveHeadersEnd and will be shown as 65ms.

Proxy time is proxyEnd - proxyStart, will be rounded to 0ms.

Send time is sendEnd - sendStart, also will be rounded to 0ms.

Waiting time is receiveHeadersEnd - sendEnd, 63ms.

So we see that about 2ms are not classified - this is time before proxy and between proxy and send.

[Sylvain Caillet]

Hello, 

Thank you for your anwer. I can understand with your example that the latency could be different from the waiting time. 

But what I really need is to export network waterfall as HAR format. And I am not sure the HAR 1.2 spec is really respected by the export tool of the chrome dev. 

Many times, I see differences for an HAR Entry between its request.time and the sum of its timings (that are not -1). And Its weird ! Because many HAR viewers check for the integrity of the file to display the content, and they detect an issue !

If you check the HAR spec (see http://www.softwareishard.com/blog/har-12-spec/#timings), request.time is supposed to the sum of all times except ssl. I copy here an extract of one HAR I made with Chrome :

         "time": 504,

         "timings": {

          "blocked": -1,

          "dns": 15,

          "connect": -1,

          "send": 0,

          "wait": 503,

          "receive": 0,

          "ssl": -1

        },

and 504 != 503+15

So what the good times ?

For your information, I get the same issue on PCs using a Proxy or not.

2013/8/23 Eugene Klyuchnikov <eus...@google.com>

[Eugene Klyuchnikov]

Oh, I see.

 The problem is that currently we do not calculate 'blocked' time properly.

 Fix: https://codereview.chromium.org/23308009/

[Eugene Klyuchnikov]

Hello.

The fix has been landed recently.

Eugene Klyuchnikov |

SW Engineer |

eus...@google.com |

Fight fire with fire!