Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Understanding HTTP/2 prioritization

20e958629852b653fad35c99706fc3ac?s=47 Moto Ishizawa
June 15, 2015
Technology
17
4.9k

Understanding HTTP/2 prioritization

20e958629852b653fad35c99706fc3ac?s=128

Moto Ishizawa

June 15, 2015
Tweet

More Decks by Moto Ishizawa

See All by Moto Ishizawa
20e958629852b653fad35c99706fc3ac?s=48 summerwind
0
110
20e958629852b653fad35c99706fc3ac?s=48 summerwind
1
5.7k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
1
560
20e958629852b653fad35c99706fc3ac?s=48 summerwind
5
1.5k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
2
3.2k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
17
2.9k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
1
1.8k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
3
2.2k
20e958629852b653fad35c99706fc3ac?s=48 summerwind
5
3.2k

Other Decks in Technology

See All in Technology
848cae20fe522dfbecef7743f107fe0f?s=48 nishino
0
2.4k
4861686276b2f990387eaef28b099db0?s=48 niyarin
0
110
2a37329cdb03944fdf86b0e54397ff30?s=48 veliswaboya
1
100
252e6c31a6452aa80deb9ad0107975c7?s=48 attakei
0
220
6ddc65998177a0f05be629dc31321a8f?s=48 kken78
0
150
7cd783377515bdf8207062840b7b2f4e?s=48 soracom
PRO
1
420
4924e08c88a442edbffd87b91cb45131?s=48 zaki_lknr
0
530
4e7f712e4bba241f579d3dc0eaf130d4?s=48 mito201
0
380
5e811ea39e141c433cdd961bbaa03122?s=48 masayoshi
PRO
8
1.4k
6f455f3ddfaa8a1c3a8a03ecd5d73d4f?s=48 hirakichi
0
130
0abc75d0ead1b1300178fad993308c67?s=48 motchy1204
1
130
380bcd2ab751f5838abd8219df53e5fe?s=48 tomoki10
5
3.1k

Featured

See All Featured
Aff5641764408271f7bc398f2097edd0?s=48 denniskardys
222
120k
Bfd6b681ec6e8c9bef82ff0521c364f7?s=48 kastner
55
2k
C44e1f7e22c3f23cff7bc130871047ef?s=48 eileencodes
117
26k
6bb82b13cda86d3b821fa44100335ddf?s=48 thoeni
6
780
A415db3ac9e9668acbc1fb36eead84ac?s=48 mthomps
43
2.4k
C4de88ea47538e4594750e3861a341c8?s=48 brettharned
96
3.2k
78b475797a14c84799063c7cd073962f?s=48 holman
463
280k
5f2da528927a2ec9ba4fec2069cbc958?s=48 kneath
224
15k
E190023b66e2b8aa73a842b106920c93?s=48 zenorocha
300
40k
168ccec72eee0530b818d44f3fedaacf?s=48 shlominoach
177
7.9k
91cefdf141106fa10674aae74ce05890?s=48 yeseniaperezcruz
304
32k
Ded01cdab114abe4ec13511e4c25b9bb?s=48 andyhume
66
4.1k

Transcript

  1. Understanding HTTP/2 prioritization Moto Ishizawa @summerwind

  2. Who? :-) • Platform Engineer @ Yahoo! JAPAN • Beacon

    platforms, Data pipelines • Reviewer of HPBN Japanese Edition • Sections: HTTP/1.1, HTTP/2, WebRTC • HTTP/2 Japan Community • RFC7540 Japanese Translation, h2spec

  3. HTTP/2 Prioritization • HTTP/2 client controls the transmission order of

    resources by priority • Priority is expressed by dependency and weight • Priority is a hint, server may ignore it • In the browser, there is a possibility that the priority affects the rendering • Prioritization might adversely affect the critical rendering path

  4. Priority Tree 0 3 128 5 64 7 16 9

    16 Stream ID Weight Dependency

  5. Priority Tree 0 3 128 5 64 7 16 9

    16 All streams are set weight 16 by default. All streams depend on the Stream ID 0 by default.

  6. Priority Tree 0 3 128 5 64 7 16 9

    16 The priority of the stream is determined by the relative proportions of the weights. Stream ID 3 should receive two-thirds of available resources. The priority of the stream that depends on another stream is determined by the weight of dependent stream. Stream ID 7 should receive half of the resources of Stream ID 3.

  7. Implementation status Server Name Version Support nghttp2 1.0.2 YES H2O

    1.2.0 YES Apache Traffic Server 5.3.0 NO Browser Name Version Support Firefox 38.0.5 YES Chrome 43.0.2357.65 YES (Weight only) Edge 0.11.10074.0 (Preview) NO Safari 9,0 (Preview) NO

  8. Testing the prioritization of browsers • Test page • CSS

    in the <head> × 3 • Javascript in the <head> × 3 • JavaScript in the <body> × 3 • Image in the <body> × 3 • Size of all resources: 100KB • Server • nghttpx v1.0.1 <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>Test</title> <link href="tests/1.css" rel="stylesheet"> <link href="tests/2.css" rel="stylesheet"> <link href="tests/3.css" rel="stylesheet"> <script src="tests/1.js"></script> <script src="tests/2.js"></script> <script src="tests/3.js"></script> </head> <body> <h1>Test</h1> <img src=“tests/1.jpg” alt="1"> <img src=“tests/2.jpg“ alt="2"> <img src=“tests/3.jpg” alt="3"> <script src="tests/4.js"></script> <script src="tests/5.js"></script> <script src="tests/6.js"></script> </body> </html>

  9. Firefox’s Priority Tree 9 1. Initialization 0 3 7 201

    1 1 11 1 5 101 Initializing the priority tree by PRIORITY frames.

  10. Firefox’s Priority Tree 9 2. HTML 0 3 7 201

    1 1 13 32 11 1 5 101 Stream for HTML. Prioritized by HEADERS frame.

  11. Firefox’s Priority Tree 9 3. CSS 0 3 7 201

    1 1 13 32 19 32 17 32 15 32 11 1 5 101 Streams for CSS.
 Prioritized by HEADERS frames.

  12. Firefox’s Priority Tree 9 25 4. JavaScript in the <head>

    0 3 7 201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 5 101 Streams for JavaScript.
 Prioritized by HEADERS frames.

  13. Firefox’s Priority Tree 9 25 5. Image 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 5 101 Streams for Image. Prioritized by HEADERS frames.

  14. Firefox’s Priority Tree 9 25 6. JavaScript in the <body>

    0 3 7 201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101 Streams for JavaScript. Prioritized by HEADERS frames.

  15. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  16. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  17. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  18. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  19. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  20. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  21. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  22. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  23. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  24. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  25. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  26. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  27. Firefox’s Priority Tree 9 25 7. Download 0 3 7

    201 1 1 32 13 32 19 32 21 32 23 32 17 32 15 32 11 1 27 22 29 22 31 22 35 32 37 32 33 32 5 101

  28. Firefox’s Timeline 13 15 17 19 21 23 25 27

    29 31 33 35 37 HEADERS (Request) HEADERS (Response) DATA

  29. Chrome’s Priority Tree 1. HTML 0 1 256 Stream for

    HTML. Prioritized by HEADERS frame.

  30. 5 Chrome’s Priority Tree 2. CSS 0 1 256 3

    220 220 7 220 Streams for CSS.
 Prioritized by HEADERS frames.

  31. 5 Chrome’s Priority Tree 3. JavaScript in the <head> 0

    1 256 3 220 220 7 220 9 183 11 183 13 183 Streams for JavaScript. Prioritized by HEADERS frames.

  32. 5 Chrome’s Priority Tree 4. JavaScript in the <body> 0

    1 256 15 183 17 183 19 183 3 220 220 7 220 9 183 11 183 13 183 Streams for JavaScript. Prioritized by HEADERS frames.

  33. 5 Chrome’s Priority Tree 5. Image 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 Streams for Image. Prioritized by HEADERS frames. 15 183 17 183 19 183

  34. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  35. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  36. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  37. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  38. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  39. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  40. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  41. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  42. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  43. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  44. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  45. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  46. 5 Chrome’s Priority Tree 6. Download 0 1 256 3

    220 220 7 220 9 183 11 183 13 183 21 110 23 110 25 110 15 183 17 183 19 183

  47. Chrome’s Timeline 1 3 5 7 9 11 13 15

    17 19 21 23 25 HEADERS (Request) HEADERS (Response) DATA

  48. Edge’s Priority Tree 1. HTML 0 1 16

  49. 5 Edge’s Priority Tree 2. CSS, JavaScript, Image 0 1

    16 15 16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16 Streams for CSS, JavaScript, and Image.
 Priority is not specified. Default value is used.

  50. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  51. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  52. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  53. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  54. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  55. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  56. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  57. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  58. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  59. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  60. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  61. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  62. 5 Edge’s Priority Tree 3. Download 0 1 16 15

    16 17 16 19 16 3 16 16 7 16 9 16 11 16 13 16 21 16 23 16 25 16

  63. Edge’s Timeline 1 3 5 7 9 11 13 15

    17 19 21 23 25 HEADERS (Request) HEADERS (Response) DATA

  64. The prioritization strategy of browsers • Firefox builds the priority

    tree that is optimized for Web pages • Priority order: CSS, JavaScript, Images • Chrome reuses the prioritization strategy of SPDY era that is used only weight • The difference in weight is small… there is room for optimization! • Edge does not support the prioritization • It seems to control the download of the resource by the timing of request...

  65. Conclusion • HTTP/2 prioritization consists of dependency and weight •

    Client notifies the priority, server builds the priority tree • Each browser have different prioritization strategy • The use of priority dependencies may produce better results • Need to measurement the effect of HTTP/2 prioritization! • But there is no tool that can measure the prioritization of HTTP/2...

  66. Thanks!