Journey of APK from Compile to Start

This was the keynote presentation at Droidkaigi, 2019 in Tokyo, Japan.

Transcript

1. Journey of APK from
   Compile to Start
   @droid_singh @_romichandra_
   

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2. “Success is a journey not a destination”
   - Internet
   

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3. Components of APK
   

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4. Components of APK
   Basic
   

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5. Components of APK
   Complex
   

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6. Where do these come from?
   

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7. Lets magnify this
   

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8. View Slide

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10. View Slide

11. AAPT
    •Android Asset Packaging tool.
    •Creates R.java file.
    •Tool for creating, updating and viewing
    components the zip archive.
    

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12. AAPT
    •Android Asset Packaging tool.
    •Creates R.java file.
    •Tool for creating, updating and viewing
    components the zip archive.
    

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13. •IDs are generated by AAPT to refer resources.
    •Resource bit:
    How R is prepared?
    P P T T N N N N
    0x7f
    

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14. Category
    •IDs are generated by AAPT to refer resources.
    •Resource bit:
    How R is prepared?
    P P T T N N N N
    0x7f Next hex available
    

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15. public static final class id {
    public static final int ALT=0x7f070000;
    public static final int CTRL=0x7f070001;
    public static final int FUNCTION=0x7f070002;
    public static final int META=0x7f070003;
    public static final int SHIFT=0x7f070004;
    public static final int SYM=0x7f070005;
    public static final int action_bar=0x7f070006;
    public static final int action_bar_activity_content=0x7f070007;
    public static final int action_bar_container=0x7f070008;
    }
    

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16. 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height=“match_parent">
    
    

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17. 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/action_bar_constraintLayout"
    android:layout_width="match_parent"
    android:layout_height=“match_parent">
    
    

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18. public static final class id {
    public static final int ALT=0x7f070000;
    public static final int CTRL=0x7f070001;
    public static final int FUNCTION=0x7f070002;
    public static final int META=0x7f070003;
    public static final int SHIFT=0x7f070004;
    public static final int SYM=0x7f070005;
    public static final int action_bar=0x7f070006;
    public static final int action_bar_activity_content=0x7f070007;
    public static final int action_bar_constraintLayout=0x7f070008;
    public static final int action_bar_container=0x7f070009;
    }
    PP
    TT
    NNNN
    

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19. R
    Java/Kt files Resources
    R.id.action_constraintLayout
    

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21. Java
    Java
    class
    Java
    .
    .
    .
    .
    javac
    Java
    javac
    javac
    javac
    class
    class
    class
    dx
    or
    d8
    dex
    Proguard
    

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22. Java
    Java
    class
    Java
    .
    .
    .
    .
    javac
    Java
    javac
    javac
    javac
    class
    class
    class
    dx
    or
    d8
    dex
    Proguard
    

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23. Java
    Java
    class
    Java
    .
    .
    .
    .
    javac
    Java
    javac
    javac
    javac
    class
    class
    class
    dx
    or
    d8
    dex
    Proguard
    

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24. Java
    Java
    class
    Java
    .
    .
    .
    .
    javac
    Java
    javac
    javac
    javac
    class
    class
    class
    dx
    or
    d8
    dex
    Proguard
    

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25. Java
    Java
    class
    Java
    .
    .
    .
    .
    javac
    Java
    javac
    javac
    javac
    class
    class
    class
    dex
    Proguard
    Optimization 

    layers
    dx
    or
    d8
    

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26. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    

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27. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    public static long sumArray(int[]);
    Code:
    0: lconst_0
    1: lstore_1
    2: aload_0
    3: astore_3
    4: aload_3
    5: arraylength
    6: istore 4
    8: iconst_0
    9: istore 5
    11: iload 5
    13: iload 4
    15: if_icmpge 36
    18: aload_3
    19: iload 5
    21: iaload
    22: istore 6
    24: lload_1
    25: iload 6
    27: i2l
    28: ladd
    29: lstore_1
    30: iinc 5, 1
    33: goto 11
    36: lload_1
    37: lreturn
    .class
    

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28. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    public static long sumArray(int[]);
    Code:
    0: lconst_0
    1: lstore_1
    2: aload_0
    3: astore_3
    4: aload_3
    5: arraylength
    6: istore 4
    8: iconst_0
    9: istore 5
    11: iload 5
    13: iload 4
    15: if_icmpge 36
    18: aload_3
    19: iload 5
    21: iaload
    22: istore 6
    24: lload_1
    25: iload 6
    27: i2l
    28: ladd
    29: lstore_1
    30: iinc 5, 1
    33: goto 11
    36: lload_1
    37: lreturn
    .class
    11: iload 5
    13: iload 4
    15: if_icmpge 36
    18: aload_3
    19: iload 5
    21: iaload
    22: istore 6
    24: lload_1
    25: iload 6
    27: i2l
    28: ladd
    29: lstore_1
    30: iinc 5, 1
    33: goto 11
    
    Dispatches 14
    Read 20
    Write 16
    

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29. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    

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30. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    0000: const-wide/16 v2, #int 0 // #0
    0002: array-length v1, v6
    0003: const/4 v0, #int 0 // #0
    0004: if-ge v0, v1, 000d // +0009
    0006: aget v4, v6, v0
    0008: int-to-long v4, v4
    0009: add-long/2addr v2, v4
    000a: add-int/lit8 v0, v0, #int 1 // #01
    000c: goto 0004 // -0008
    000d: return-wide v2
    .dex:
    

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31. public static long sumArray(int[] arr){
    long sum = 0;
    for(int i: arr){
    sum += i;
    }
    return sum;
    }
    0000: const-wide/16 v2, #int 0 // #0
    0002: array-length v1, v6
    0003: const/4 v0, #int 0 // #0
    0004: if-ge v0, v1, 000d // +0009
    0006: aget v4, v6, v0
    0008: int-to-long v4, v4
    0009: add-long/2addr v2, v4
    000a: add-int/lit8 v0, v0, #int 1 // #01
    000c: goto 0004 // -0008
    000d: return-wide v2
    .dex:
    0004: if-ge v0, v1, 000d // +0009
    0006: aget v4, v6, v0
    0008: int-to-long v4, v4
    0009: add-long/2addr v2, v4
    000a: add-int/lit8 v0, v0, #int 1 // #01
    000c: goto 0004 // -0008
    
    Dispatches 6
    Reads 10
    Writes 6
    

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32. View Slide

33. View Slide

34. ZipAlign
    

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35. ZipAlign
    •Android has a 4 byte boundary memory mapping
    

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36. ZipAlign
    •Misaligned data slows data access performance.
    

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37. ZipAlign
    •Misaligned data slows data access performance.
    •ZipAlign step results in aligning all the data in 4 byte
    boundary.
    

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38. Compilation
    Installation
    

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39. View Slide

40. Dalvik
    Upto KitKat
    

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41. Dalvik
    Upto KitKat
    •Byte Code Verification
    

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42. Dalvik
    Upto KitKat
    •Byte Code Verification
    To check the integrity of Dex
    

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43. Dalvik
    Upto KitKat
    •Byte Code Verification
    To check the integrity of Dex
    Done at install time rather than run
    time.
    

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44. Dalvik
    Upto KitKat
    •Byte Code Verification
    To check the integrity of Dex
    Done at install time rather than run
    time.
    Validity of indices and structure of
    file.
    

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45. Dalvik
    Upto KitKat
    •Byte Code Verification
    To check the integrity of Dex
    Done at install time rather than run
    time.
    Validity of indices and structure of
    file.
    Ordering of the instructions.
    

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46. Dalvik
    Upto KitKat
    •Optimizations
    

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47. Dalvik
    Upto KitKat
    •Optimizations
    VTable Method Index for method
    invocation.
    

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48. Dalvik
    Upto KitKat
    •Optimizations
    VTable Method Index for method
    invocation.
    Replacing high volume of methods
    with their inline versions.
    

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49. Dalvik
    Upto KitKat
    •Optimizations
    VTable Method Index for method
    invocation.
    Replacing high volume of methods
    with their inline versions.
    Prune empty methods.
    

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50. Dalvik
    Upto KitKat
    •Optimizations
    VTable Method Index for method
    invocation.
    Replacing high volume of methods
    with their inline versions.
    Prune empty methods.
    Pre computations.
    

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51. Dalvik
    Upto KitKat
    •Optimizations
    VTable Method Index for method
    invocation.
    Replacing high volume of methods
    with their inline versions.
    Prune empty methods.
    Pre computations.
    dexopt
    ODEX
    
    

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52. ART
    In Lollipop
    

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53. ART
    In Lollipop
    •Preloading
    boot.art
    boot.oat
    

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54. ART
    In Lollipop
    •Preloading
    boot.art
    boot.oat
    Compiler

    Driver
    ELF file
    •Load Compiler
    

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55. ART
    In Lollipop
    •Preloading
    boot.art
    boot.oat
    Compiler

    Driver
    ELF file
    dex2Oat
    •Load Compiler (AOT)
    

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56. ART
    •Preloading
    boot.art
    boot.oat
    Compiler

    Driver
    ELF file
    •Load Compiler
    Dex
    Resolve
    classes
    Verify
    classes
    Init
    classes
    Compile
    classes
    ELF
    File
    
    

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57. Problem:
    

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58. Problem:
    

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59. Hybrid: JIT+AOT
    

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60. Hybrid: JIT+AOT
    From Android Nougat
    

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61. Profile guided Compilation
    Profile Files
    App
    App Execution

    (Interpret/JIT)
    Profile guided 

    compile
    Compiled App
    

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62. dex file,
    oat file
    

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63. dex file,
    oat file
    ART
    

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64. dex file,
    oat file
    ART
    Execute

    method
    

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65. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    

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66. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Y
    

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67. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    

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68. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    

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69. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    Run code

    from jit cache
    Y
    

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70. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Run code

    from jit cache
    Y
    

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71. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Run code

    from jit cache
    Y
    Record
    Profiles
    info
    

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72. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Is

    it hot?
    Run code

    from jit cache
    Y
    Record
    Profiles
    info
    

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73. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Is

    it hot?
    JIT

    Cache
    Run code

    from jit cache
    Y
    Record
    Profiles
    info
    Y
    

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74. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Is

    it hot?
    JIT

    Cache
    Run code

    from jit cache
    Y
    Record
    Profiles
    info
    N
    Y
    

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75. dex file,
    oat file
    ART
    Execute

    method
    Is

    it compiled

    ?
    Is it

    JIT
    compiled
    Y
    Run code

    from .oat
    file
    N
    N
    Interpreter
    Is

    it hot?
    JIT

    Cache
    Run code

    from jit cache
    Y
    Record
    Profiles
    info
    N
    Y
    When Profile guided
    compilation 

    occurs?
    

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76. When Profile guided
    compilation 

    occurs?
    

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77. Compilation
    Installation
    Optimizations
    

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78. “Abstractions increase the productivity of developer but they
    can be overhead for runtime”
    

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79. Optimizations
    1. Constant Folding
    numberOfDays = 2 + 2 + previous;
    add-int/lit8 v0, v2, #int 4
    

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80. 2. Inlining
    fun len (string: String): Int{
    return string.length
    }
    

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81. 2. Inlining
    fun len (string: String): Int{
    return string.length
    }
    const-string v0, "string"
    invoke-static {v1, v0}, Lkotlin/jvm/internal/Intrinsics;.checkParameterIsNotNull
    invoke-virtual {v1}, Ljava/lang/String;.length
    move-result v0
    return v0
    

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82. 2. Inlining
    fun len (string: String): Int{
    return string.length
    }
    const-string v0, "string"
    invoke-static {v1, v0}, Lkotlin/jvm/internal/Intrinsics;.checkParameterIsNotNull
    invoke-virtual {v1}, Ljava/lang/String;.length
    move-result v0
    return v0
    

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83. const-string v0, "string"
    if-nez v1, :continue
    invoke-static {v1}, throwParameterIsNullException
    :continue
    invoke-virtual {v1}, Ljava/lang/String;.length
    move-result v0
    return v0
    

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84. 3. Bounds Check Elimination
    int sum = 0;
    for (int i = 0; i < size; i++) {
    sum += array[i];
    }
    

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85. 3. Bounds Check Elimination
    int sum = 0;
    for (int i = 0; i < size; i++) {
    sum += array[i];
    }
    

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86. 4. Strength Reduction
    5. Dead Code Elimination
    6. DexLayout
    7. Class Hierarchy Analysis
    And much more…..
    

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87. Compilation
    ??
    

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88. View Slide

89. View Slide

90. View Slide

91. View Slide

92. View Slide

93. View Slide

94. View Slide

95. MULTIDEX: The 64k LIMIT
    

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96. MULTIDEX: THE AFTERMATH
    •Adverse effect on App Startup
    •Build time increases.
    •Strange errors during runtime
    •Strangers in Crashyltics..
    

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97. MULTIDEX: THE AFTERMATH
    •Adverse effect on App Startup
    •Build time increases.
    •Strange errors during runtime
    •Strangers in Crashyltics..
    

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98. MULTIDEX: THE AFTERMATH
    •Adverse effect on App Startup
    •Build time increases.
    •Strange errors during runtime
    •Strangers in Crashyltics..
    

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99. MULTIDEX: HOW?
    

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100. DirectClass

     FileConsumer
     .class
     Validate & Lock
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     

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101. DirectClass

     FileConsumer
     .class
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     Validate & Lock
     

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102. DirectClass

     FileConsumer
     .class
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     Validate & Lock
     

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103. DirectClass

     FileConsumer
     .class
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     Validate & Lock
     

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104. DirectClass

     FileConsumer
     .class
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     Validate & Lock
     

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105. DirectClass

     FileConsumer
     .class
     ClassTranslatorTask
     ClassDefItemConsumer
     Update global indices
     Release the lock
     Write
     Copyright: AOSP
     Validate & Lock
     

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106. Compilation
     Installation
     Optimizations
     App

     Startup
     

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107. App Startup: 

     Evolving Better with ART
     

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108. View Slide

109. View Slide

110. What’s wrong?
     

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111. View Slide

112. 10s
     

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113. View Slide

114. Time for tips
     • Use lazy initializations.
     • Don’t use reflections at time of APP startup
     • Initialize all the SDKs in background
     • Load images asynchronously.
     • Avoid nesting layout
     

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115. Let us all be an ARTist
     

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116. Thank you'
     @droid_singh
     amanjeetsingh150
     @_romichandra_
     romichandra
     

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