Leveraging Program Analysis to Reduce User-Perceived Latency in Mobile Applications

Presentation slides of the paper "Leveraging Program Analysis to Reduce User-Perceived Latency in Mobile Applications" at International Conference on Software Engineering (ICSE) 2018.

The presentation can be found at: https://youtu.be/8KUPsG4bByU

Transcript

1. Leveraging Program Analysis to Reduce
   User-Perceived Latency in Mobile Applications
   Yixue Zhao, Marcelo Schmitt Laser, Yingjun Lyu, and Nenad Medvidović
   University of Southern California
   May 30, 2018
   

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2. Motivating Example
   

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3. Motivating Example
   

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4. Motivating Example
   

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5. Motivating Example
   Latency!
   

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6. Motivating Example
   

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7. Motivating Example
   

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8. Outline
   • Existing prefetching techniques
   • Novel prefetching technique: PALOMA
   • Give me an example
   • How well does PALOMA do?
   • Summary & takeaways
   

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9. Existing Prefetching Techniques
   Existing approaches:
   • Server-based
   • Human-based
   • History-based
   • Domain-based
   

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10. Existing Prefetching Techniques
    Existing approaches:
    • Server-based à not accessible
    • Human-based
    • History-based
    • Domain-based
    

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11. Existing Prefetching Techniques
    Existing approaches:
    • Server-based à not accessible
    • Human-based à manual & error-prone
    • History-based
    • Domain-based
    

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12. Existing Prefetching Techniques
    Existing approaches:
    • Server-based à not accessible
    • Human-based à manual & error-prone
    • History-based à time-consuming
    • Domain-based
    

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13. Existing Prefetching Techniques
    Existing approaches:
    • Server-based à not accessible
    • Human-based à manual & error-prone
    • History-based à time-consuming
    • Domain-based à not general
    

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14. Novel Prefetching Technique: PALOMA
    • Server-based
    • Human-based
    • History-based
    • Domain-based
    Client-only
    Automatic
    No historical data
    Domain-independent
    

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15. Meet PALOMA J
    Program Analysis for Latency Optimization of Mobile Apps
    • Client-only
    • Automatic
    • No historical data
    • Domain-independent
    

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16. Key Insights
    • App code has useful information
    • “User think time” provides opportunities
    

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17. PALOMA in a Nutshell
    Code
    Analysis
    App
    Instrumentation
    Optimized
    App
    

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18. Original App Workflow
    Origin
    Server
    Latency!
    Original
    App
    • App interacts with server
    • Network latency
    

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19. PALOMA Workflow
    Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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20. PALOMA Workflow
    Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    “what”
    

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21. PALOMA Workflow
    Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    “when”
    

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22. PALOMA Workflow
    Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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23. PALOMA Workflow
    Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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24. Outline
    • Existing prefetching techniques
    • Novel prefetching technique: PALOMA
    Ø Give me an example
    • How well does PALOMA do?
    • Summary & takeaways
    

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25. Illustrating Example
    • Event app:
    1. choose city name
    

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26. Illustrating Example
    • Event app:
    1. choose city name
    2. click submit to get event
    information
    

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27. Illustrating Example
    • Event app:
    1. choose city name
    2. click submit to get event
    information
    

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28. Illustrating Example
    • Event app:
    1. choose city name
    2. click submit to get event
    information
    FINALE
    The original aesthetic and
    unconventional Do-it-Yourself
    attitude of the show creates a raw
    energy that simmers through a haze
    of confetti, smoke and pulsing lights.
    

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29. Illustrating Example
    • Event app:
    1. choose city name
    2. click submit to get event
    information
    • Objective:
    send event query before
    clicking submit button
    

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30. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    

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31. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    

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32. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    

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33. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    

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34. Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    PALOMA Workflow
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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35. String Analysis Callback Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    Answer “what” to prefetch
    * Yellow = terms defined in the paper
    

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36. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    Answer “what” to prefetch
    • Identify URL Spot
    * Yellow = terms defined in the paper
    Callback Analysis
    

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37. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    * Yellow = terms defined in the paper
    Callback Analysis
    

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38. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    * Yellow = terms defined in the paper
    Callback Analysis
    

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39. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    • Output à URL Map
    { url1: [ “http://event?&cityName=”, Line7] }
    * Yellow = terms defined in the paper
    Callback Analysis
    

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40. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    • Identify Target Callback
    * Yellow = terms defined in the paper
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    • Output à URL Map
    { url1: [ “http://event?&cityName=”, Line7] }
    Callback Analysis
    

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41. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    • Identify Target Callback
    • Extract Callback Control Flow Graph
    (CCFG)
    * Yellow = terms defined in the paper
    { url1: [ “http://event?&cityName=”, Line7] }
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    • Output à URL Map
    Callback Analysis
    

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42. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    • Identify Target Callback
    • Extract Callback Control Flow Graph
    (CCFG)
    • Identify Trigger Callback
    * Yellow = terms defined in the paper
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    • Output à URL Map
    { url1: [ “http://event?&cityName=”, Line7] }
    Callback Analysis
    

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43. String Analysis
    Static Analysis Phase
    Answer “when” to prefetch
    • Identify Target Callback
    • Extract Callback Control Flow Graph
    (CCFG)
    • Identify Trigger Callback
    • Output à Trigger Map
    { [ onCreate ]: [ url1 ] }
    { [ onItemSelected ]: [ url1 ] }
    * Yellow = terms defined in the paper
    Answer “what” to prefetch
    • Identify URL Spot
    • Static URL string value analysis
    Interpret concrete values
    • Dynamic URL string value analysis
    Identify Definition Spots
    • Output à URL Map
    { url1: [ “http://event?&cityName=”, Line7] }
    Callback Analysis
    

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44. Static Analysis Phase
    Push to Proxy
    Legend Optimized
    App
    Original
    App
    

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45. Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    PALOMA Workflow
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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46. Automatically enable prefetching
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    • Output à Optimized App
    App Instrumentation Phase
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    { url1: [ “http://event?&cityName=”, Line7] }
    

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47. App Instrumentation Phase
    Automatically enable prefetching
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    • Output à Optimized App
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    { url1: [ “http://event?&cityName=”, Line7] }
    

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48. { url1: [ “http://event?&cityName=”, Line7] }
    App Instrumentation
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 } 1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    Definition
    Spot
    

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49. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    App Instrumentation
    { url1: [ “http://event?&cityName=”, Line7] }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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50. App Instrumentation
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    

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51. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    18 }
    19 }
    App Instrumentation
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    Trigger
    Callback
    

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52. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    App Instrumentation
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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53. { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    App Instrumentation
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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54. App Instrumentation
    { [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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55. App Instrumentation
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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56. App Instrumentation
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse(connection.getInputStream());
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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57. App Instrumentation
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    1. Update URL Map
    2. Trigger prefetching
    3. Redirect Requests
    

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58. Static Analysis App
    Instrumentation Optimized App
    String
    Analysis
    Callback
    Analysis
    PALOMA Workflow
    Original
    App
    Proxy
    Runtime
    Prefetching
    Origin
    Server
    offline online
    

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59. Proxy
    Runtime
    Prefetching
    Origin
    Server
    Optimized App
    PALOMA
    at runtime
    

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60. Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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61. Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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62. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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63. Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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64. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    Unknown
    Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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65. Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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66. Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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67. 1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    Runtime Prefetching Phase
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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68. Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    empty
    cache
    { url1: [ “http://event?&cityName=”, Line7] }
    

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69. Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    empty
    cache
    { url1: [ “http://event?&cityName=”, “Berlin”] }
    

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70. Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    empty
    cache
    { url1: [ “http://event?&cityName=”, “Berlin”] }
    

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71. Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    empty
    cache
    { url1: [ “http://event?&cityName=Berlin”] }
    

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72. url1’s
    response
    Runtime Prefetching Phase
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    

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73. Runtime Prefetching Phase
    url1’s
    response
    

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74. Runtime Prefetching Phase
    url1’s
    response
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    

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75. Runtime Prefetching Phase
    url1’s
    response
    1 class MainActivity{
    2 String cityName;
    3 protected void onCreate(){
    4 //register onItemSelected event
    5 cityNameSpinner.setOnItemSelectedListener(new View.OnItemSelectedListener(){
    6 public void onItemSelected() {
    7 cityName = cityNameSpinner.getSelectedItem().toString();
    sendDefinition(cityName, url1, 2);
    triggerPrefetch(url1);
    8 }});
    9 //register onClick event
    10 submitBtn.setOnClickListener(new View.OnClickListener(){
    11 public void onClick(){
    12 //initialize URL
    13 URL url1 = new URL("http://event?&cityName="+cityName);
    14 //send HTTP request
    15 URLConnection connection = url1.openConnection();
    16 Parse( fetchFromProxy(connection) );
    17 }});
    triggerPrefetch(url1);
    18 }
    19 }
    

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76. FINALE
    The original aesthetic and
    unconventional Do-it-Yourself
    attitude of the show creates a raw
    energy that simmers through a haze
    of confetti, smoke and pulsing lights.
    Runtime Prefetching Phase
    url1’s
    response
    

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77. Outline
    • Existing prefetching techniques
    • Novel prefetching technique: PALOMA
    • Give me an example
    Ø How well does PALOMA do?
    • Summary & takeaways
    

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78. Evaluation
    Objectives:
    • Accuracy
    Microbenchmark
    • Effectiveness
    Microbenchmark
    32 Market Apps
    

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79. Evaluation – Microbenchmark
    DS1,1
    1 - H
    DS1,1
    2 - NP
    DS1,2
    DS1,1
    DS1,1
    4 - NH
    DS1,2
    DS1,2
    5 - NP
    DS1,1
    DS2,1
    8 - NP
    DS1,1
    DS1,1
    6 - H
    DS2,1
    DS1,1
    7 - NP
    DS2,1 DS2,1
    DS1,1
    11 - NP
    DS2,2
    DS1,1
    15 - NP
    DS2,2
    DS2,1
    DS1,1
    DS2,1
    12 - NH
    DS2,2
    DS1,1
    13 - NP
    DS2,2
    DS2,1
    DS2,2
    DS1,1
    14 - NP
    DS2,1
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    19 - NP
    DS2,1
    DS1,2
    DS1,1
    17 - NP
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS1,1
    18 - NP
    DS2,2
    DS2,1
    DS1,2
    DS2,1
    22 - NP
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    DS2,1
    DS1,2
    DS1,1
    DS1,1
    24 - NH
    DS2,2
    DS2,1
    DS1,2
    DS1,2
    DS1,1
    DS2,1
    DS2,2
    DS1,1
    21 - NH
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    10 - H
    DS2,2
    DS2,1
    DS1,1
    DS2,2
    9 - NP
    3 - H
    16 - H
    20 - NP 23 - NH
    • 25 Test Cases
    # of dynamic values ≤ 2
    # of Definition Spots (DS) ≤ 2
    

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80. Evaluation – Microbenchmark
    DS1,1
    1 - H
    DS1,1
    2 - NP
    DS1,2
    DS1,1
    DS1,1
    4 - NH
    DS1,2
    DS1,2
    5 - NP
    DS1,1
    DS2,1
    8 - NP
    DS1,1
    DS1,1
    6 - H
    DS2,1
    DS1,1
    7 - NP
    DS2,1 DS2,1
    DS1,1
    11 - NP
    DS2,2
    DS1,1
    15 - NP
    DS2,2
    DS2,1
    DS1,1
    DS2,1
    12 - NH
    DS2,2
    DS1,1
    13 - NP
    DS2,2
    DS2,1
    DS2,2
    DS1,1
    14 - NP
    DS2,1
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    19 - NP
    DS2,1
    DS1,2
    DS1,1
    17 - NP
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS1,1
    18 - NP
    DS2,2
    DS2,1
    DS1,2
    DS2,1
    22 - NP
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    DS2,1
    DS1,2
    DS1,1
    DS1,1
    24 - NH
    DS2,2
    DS2,1
    DS1,2
    DS1,2
    DS1,1
    DS2,1
    DS2,2
    DS1,1
    21 - NH
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    10 - H
    DS2,2
    DS2,1
    DS1,1
    DS2,2
    9 - NP
    3 - H
    16 - H
    20 - NP 23 - NH
    • 25 Test Cases
    # of dynamic values ≤ 2
    # of Definition Spots (DS) ≤ 2
    • The location of DS
    Prefetchable
    Non Prefetchable (NP)
    Hit (H)
    Non Hit (NH)
    Trigger
    Point
    

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81. • 25 Test Cases
    # of dynamic values ≤ 2
    # of Definition Spots (DS) ≤ 2
    • The location of DS
    Evaluation – Microbenchmark
    DS1,1
    1 - H
    DS1,1
    2 - NP
    DS1,2
    DS1,1
    DS1,1
    4 - NH
    DS1,2
    DS1,2
    5 - NP
    DS1,1
    DS2,1
    8 - NP
    DS1,1
    DS1,1
    6 - H
    DS2,1
    DS1,1
    7 - NP
    DS2,1 DS2,1
    DS1,1
    11 - NP
    DS2,2
    DS1,1
    15 - NP
    DS2,2
    DS2,1
    DS1,1
    DS2,1
    12 - NH
    DS2,2
    DS1,1
    13 - NP
    DS2,2
    DS2,1
    DS2,2
    DS1,1
    14 - NP
    DS2,1
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    19 - NP
    DS2,1
    DS1,2
    DS1,1
    17 - NP
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS1,1
    18 - NP
    DS2,2
    DS2,1
    DS1,2
    DS2,1
    22 - NP
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    DS2,1
    DS1,2
    DS1,1
    DS1,1
    24 - NH
    DS2,2
    DS2,1
    DS1,2
    DS1,2
    DS1,1
    DS2,1
    DS2,2
    DS1,1
    21 - NH
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    10 - H
    DS2,2
    DS2,1
    DS1,1
    DS2,2
    9 - NP
    3 - H
    16 - H
    20 - NP 23 - NH
    Trigger
    Point
    Prefetchable
    Non Prefetchable (NP)
    Hit (H)
    Non Hit (NH)
    

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82. Evaluation – Microbenchmark
    DS1,1
    1 - H
    DS1,1
    2 - NP
    DS1,2
    DS1,1
    DS1,1
    4 - NH
    DS1,2
    DS1,2
    5 - NP
    DS1,1
    DS2,1
    8 - NP
    DS1,1
    DS1,1
    6 - H
    DS2,1
    DS1,1
    7 - NP
    DS2,1 DS2,1
    DS1,1
    11 - NP
    DS2,2
    DS1,1
    15 - NP
    DS2,2
    DS2,1
    DS1,1
    DS2,1
    12 - NH
    DS2,2
    DS1,1
    13 - NP
    DS2,2
    DS2,1
    DS2,2
    DS1,1
    14 - NP
    DS2,1
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    19 - NP
    DS2,1
    DS1,2
    DS1,1
    17 - NP
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS1,1
    18 - NP
    DS2,2
    DS2,1
    DS1,2
    DS2,1
    22 - NP
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    DS2,1
    DS1,2
    DS1,1
    DS1,1
    24 - NH
    DS2,2
    DS2,1
    DS1,2
    DS1,2
    DS1,1
    DS2,1
    DS2,2
    DS1,1
    21 - NH
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    10 - H
    DS2,2
    DS2,1
    DS1,1
    DS2,2
    9 - NP
    3 - H
    16 - H
    20 - NP 23 - NH
    Prefetchable
    Non Prefetchable (NP)
    Hit (H)
    Non Hit (NH)
    • 25 Test Cases
    # of dynamic values ≤ 2
    # of Definition Spots (DS) ≤ 2
    • The location of DS
    Trigger
    Point
    

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83. Evaluation – Microbenchmark
    DS1,1
    1 - H
    DS1,1
    2 - NP
    DS1,2
    DS1,1
    DS1,1
    4 - NH
    DS1,2
    DS1,2
    5 - NP
    DS1,1
    DS2,1
    8 - NP
    DS1,1
    DS1,1
    6 - H
    DS2,1
    DS1,1
    7 - NP
    DS2,1 DS2,1
    DS1,1
    11 - NP
    DS2,2
    DS1,1
    15 - NP
    DS2,2
    DS2,1
    DS1,1
    DS2,1
    12 - NH
    DS2,2
    DS1,1
    13 - NP
    DS2,2
    DS2,1
    DS2,2
    DS1,1
    14 - NP
    DS2,1
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    19 - NP
    DS2,1
    DS1,2
    DS1,1
    17 - NP
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    DS1,1
    18 - NP
    DS2,2
    DS2,1
    DS1,2
    DS2,1
    22 - NP
    DS2,2
    DS1,2
    DS1,1
    DS2,2
    DS2,1
    DS1,2
    DS1,1
    DS1,1
    24 - NH
    DS2,2
    DS2,1
    DS1,2
    DS1,2
    DS1,1
    DS2,1
    DS2,2
    DS1,1
    21 - NH
    DS2,1
    DS2,2
    DS1,2
    DS1,1
    10 - H
    DS2,2
    DS2,1
    DS1,1
    DS2,2
    9 - NP
    3 - H
    16 - H
    20 - NP 23 - NH
    • 25 Test Cases
    # of dynamic values ≤ 2
    # of Definition Spots (DS) ≤ 2
    • The location of DS
    Prefetchable
    Non Prefetchable (NP)
    Hit (H)
    Non Hit (NH)
    Trigger
    Point
    

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84. Evaluation – Microbenchmark
    Check out our paper!
    

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85. Evaluation – Microbenchmark
    • Accuracy
    Precision: 100% (All prefetched requests are prefetchable)
    Recall: 100% (All prefetchable requests are prefetched)
    

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86. Evaluation – Microbenchmark
    • Accuracy
    Precision: 100% (All prefetched requests are prefetchable)
    Recall: 100% (All prefetchable requests are prefetched)
    • Effectiveness
    Average latency reduction: 99.47% (across all Hit cases)
    Average overhead: 6.44ms (across all 25 cases)
    

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87. Evaluation – Market Apps
    • 32 subject apps from Google Play
    • 11 app categories
    • App size from 312 KB to 17.8 MB
    • 2 Android users exposed to all app options
    • 4G network setting
    

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88. Evaluation – Market Apps
    • Results across the 32 subject apps
    Min. Max. Avg. Std. Dev.
    Runtime
    Requests
    1 64 13.28 14.41
    Hit Rate 7.7% 100% 47.76% 28.81%
    Latency
    Reduction
    87.41% 99.97% 98.82% 2.3%
    

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89. Summary
    

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90. Summary
    Latency!
    

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91. Summary
    Latency!
    Latency! (Systems)
    

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92. Latency! (Systems)
    Summary
    Prefetching (Program Analysis)
    Latency!
    

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93. Takeaways
    Program Analysis for Latency Optimization in Mobile Apps:
    • Client-only
    • Automatic
    • Domain-independent
    • No historical data required
    

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94. Takeaways
    Program Analysis for Latency Optimization in Mobile Apps:
    • Significant latency reduction
    • Negligible overhead
    

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95. Takeaways
    Program Analysis for Latency Optimization in Mobile Apps:
    • Foundation
    • Rigorous formulation of prefetching scenarios
    • Comprehensive & reusable microbenchmark
    

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96. Behind the Scene: co-authors
    Marcelo Schmitt Laser Yingjun Lyu advisor: Nenad Medvidović
    

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97. Behind the Scene: co-authors + acknowledgement
    William G.J. Halfond Atanas (Nasko) Rountev Yuhao Zhu
    

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98. Contact: yixue.zhao@usc.edu
    PALOMA Website: softarch.usc.edu/PALOMA
    

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