Test with and without HTTP/2

Web Performance Discuss Test Results
1

Hi there,

I want to test a site capable of HTTP/2 with HTTP/2 and without (HTTP 1.1) to see the differences in performance, session handling and so on.

I try to disable HTTP/2 via setting a firefox preference in test script:

firefoxPref	network.http.spdy.enabled.http2	false
navigate	https://www.cloudflare.com

Resulting waterfalls look strange somehow:

cloudflare - first request isn’t included in waterfall:
http://www.webpagetest.org/result/160114_FJ_NGC/1/details/

google - no request in waterfall at all:
http://www.webpagetest.org/result/160114_7A_M43/

twitter - same as with cloudflare, first request not in waterfall:
http://www.webpagetest.org/result/160114_EK_MK8/1/details/

Any ideas?

Regards, Nils

2

My guess is that Firefox falls back to SPDY if HTTP/2 is disabled and I haven’t implemented SPDY decode in the firefox agents yet. Is there a pref to disable SPDY as well? If so you’ll want to set that (since that’s what you want to test anyway).

3

Great guess, that’s it!

firefoxPref	network.http.spdy.enabled	false
firefoxPref	network.http.spdy.enabled.http2	false
navigate	https://www.cloudflare.com

http://www.webpagetest.org/result/160114_ZE_PGW/1/details/

And second firefox preference is possibly unnecessary.

4

Update: I did some testing and seems the only setting needed to disable h2 and spdy in Firefox is network.http.spdy.enabled

[code]// Disable SPDY/h2
firefoxPref network.http.spdy.enabled false

// Navigate to the page in question -navigate command is required when scripting-
navigate https://http2.akamai.com[/code]

Here is the WPT test where this has been tested: http://www.webpagetest.org/result/160401_PB_087c76159efae899356349078e43d26b/

5

Pat,

I just did a test https://www.webpagetest.org/result/161003_Y5_73272a277161f73be7fa9dd05c6ade7f/ and seems h2 is not getting disabled in Firefox anymore.

Do you know what could be the reason?

6

I see one more option called “network.http.spdy.enabled.v3-1”. When I turned this off, I was able to force HTTP2 to be turned off on FF.

firefoxPref network.http.spdy.enabled false
firefoxPref network.http.spdy.enabled.http2 false
firefoxPref network.http.spdy.enabled.v3-1 false
navigate https://http2.akamai.com

WPT: https://www.webpagetest.org/result/161004_EG_be271ece47449783d096ce88428c06bd/1/details/#waterfall_view_step1

7

I just discovered that h2 will only be disabled when using Tabs (instead of spaces) to separate Firefox settings.

For example:

  1. using spaces to separate settings renders the page over h2: https://www.webpagetest.org/result/161116_9M_1ec921eab5b2fe69b7808c495c4b176e/ I am using:
    firefoxPref network.http.spdy.enabled false
    firefoxPref network.http.spdy.enabled.http2 false
    firefoxPref network.http.spdy.enabled.v3-1 false
    navigate https://http2.akamai.com/

  2. using tabs to separate settings renders the page over h1:
    https://www.webpagetest.org/result/161116_PB_72b17d9adfedeb4d1d3747a1deb2320d/
    firefoxPref network.http.spdy.enabled false
    firefoxPref network.http.spdy.enabled.http2 false
    firefoxPref network.http.spdy.enabled.v3-1 false
    navigate https://http2.akamai.com/

When I try with Firefox itself (without WPT) h2 gets disabled by just setting “firefoxPref network.http.spdy.enabled.http2 false” within about:config

Pat, do you know if there is something on the WPT code that may cause that?

8

The scrips are always supposed to be tab delimited. There is some server-side logic that tries to convert space-delimited scripts to tab but it may not be handling the firefoxPref command correctly.

9

Yep, should be fixed now. The conversion logic didn’t treat firefoxPref as a “3 parameter” script command which was messing it up.