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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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Motivating Example
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Motivating Example
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Motivating Example
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Motivating Example
Latency!
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Motivating Example
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Motivating Example
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Outline
• Existing prefetching techniques
• Novel prefetching technique: PALOMA
• Give me an example
• How well does PALOMA do?
• Summary & takeaways
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Existing Prefetching Techniques
Existing approaches:
• Server-based
• Human-based
• History-based
• Domain-based
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Existing Prefetching Techniques
Existing approaches:
• Server-based à not accessible
• Human-based
• History-based
• Domain-based
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Existing Prefetching Techniques
Existing approaches:
• Server-based à not accessible
• Human-based à manual & error-prone
• History-based
• Domain-based
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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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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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Novel Prefetching Technique: PALOMA
• Server-based
• Human-based
• History-based
• Domain-based
Client-only
Automatic
No historical data
Domain-independent
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Meet PALOMA J
Program Analysis for Latency Optimization of Mobile Apps
• Client-only
• Automatic
• No historical data
• Domain-independent
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Key Insights
• App code has useful information
• “User think time” provides opportunities
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PALOMA in a Nutshell
Code
Analysis
App
Instrumentation
Optimized
App
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Original App Workflow
Origin
Server
Latency!
Original
App
• App interacts with server
• Network latency
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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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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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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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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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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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Outline
• Existing prefetching techniques
• Novel prefetching technique: PALOMA
Ø Give me an example
• How well does PALOMA do?
• Summary & takeaways
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Illustrating Example
• Event app:
1. choose city name
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Illustrating Example
• Event app:
1. choose city name
2. click submit to get event
information
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Illustrating Example
• Event app:
1. choose city name
2. click submit to get event
information
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Static Analysis Phase
Push to Proxy
Legend Optimized
App
Original
App
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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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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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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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{ 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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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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App Instrumentation
1. Update URL Map
2. Trigger prefetching
3. Redirect Requests
{ [ onCreate ]: [ url1 ] } { [ onItemSelected ]: [ url1 ] }
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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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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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{ [ 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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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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App Instrumentation
1. Update URL Map
2. Trigger prefetching
3. Redirect Requests
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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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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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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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Proxy
Runtime
Prefetching
Origin
Server
Optimized App
PALOMA
at runtime
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Runtime Prefetching Phase
empty
cache
{ url1: [ “http://event?&cityName=”, Line7] }
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Runtime Prefetching Phase
empty
cache
{ url1: [ “http://event?&cityName=”, Line7] }
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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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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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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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Runtime Prefetching Phase
empty
cache
{ url1: [ “http://event?&cityName=”, Line7] }
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Runtime Prefetching Phase
empty
cache
{ url1: [ “http://event?&cityName=”, Line7] }
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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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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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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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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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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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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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Runtime Prefetching Phase
url1’s
response
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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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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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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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Outline
• Existing prefetching techniques
• Novel prefetching technique: PALOMA
• Give me an example
Ø How well does PALOMA do?
• Summary & takeaways
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Evaluation
Objectives:
• Accuracy
Microbenchmark
• Effectiveness
Microbenchmark
32 Market Apps
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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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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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• 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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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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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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Evaluation – Microbenchmark
Check out our paper!
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Evaluation – Microbenchmark
• Accuracy
Precision: 100% (All prefetched requests are prefetchable)
Recall: 100% (All prefetchable requests are prefetched)
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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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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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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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Summary
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Summary
Latency!
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Summary
Latency!
Latency! (Systems)
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Latency! (Systems)
Summary
Prefetching (Program Analysis)
Latency!
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Takeaways
Program Analysis for Latency Optimization in Mobile Apps:
• Client-only
• Automatic
• Domain-independent
• No historical data required
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Takeaways
Program Analysis for Latency Optimization in Mobile Apps:
• Significant latency reduction
• Negligible overhead
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Takeaways
Program Analysis for Latency Optimization in Mobile Apps:
• Foundation
• Rigorous formulation of prefetching scenarios
• Comprehensive & reusable microbenchmark
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Behind the Scene: co-authors
Marcelo Schmitt Laser Yingjun Lyu advisor: Nenad Medvidović
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Behind the Scene: co-authors + acknowledgement
William G.J. Halfond Atanas (Nasko) Rountev Yuhao Zhu