Run Selenium automation tests on LambdaTest cloud grid
Perform automation testing on 3000+ real desktop and mobile devices online.
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package org.openqa.selenium.grid.node.config;
import com.google.auto.service.AutoService;
import com.beust.jcommander.Parameter;
import org.openqa.selenium.grid.config.ConfigValue;
import org.openqa.selenium.grid.config.HasRoles;
import org.openqa.selenium.grid.config.NonSplittingSplitter;
import org.openqa.selenium.grid.config.Role;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import static org.openqa.selenium.grid.config.StandardGridRoles.NODE_ROLE;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_DETECT_DRIVERS;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_HEARTBEAT_PERIOD;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_MAX_SESSIONS;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_REGISTER_CYCLE;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_REGISTER_PERIOD;
import static org.openqa.selenium.grid.node.config.NodeOptions.DEFAULT_SESSION_TIMEOUT;
import static org.openqa.selenium.grid.node.config.NodeOptions.NODE_SECTION;
import static org.openqa.selenium.grid.node.config.NodeOptions.OVERRIDE_MAX_SESSIONS;
@SuppressWarnings("unused")
@AutoService(HasRoles.class)
public class NodeFlags implements HasRoles {
@Parameter(
names = {"--max-sessions"},
description = "Maximum number of concurrent sessions. Default value is the number "
+ "of available processors.")
@ConfigValue(section = NODE_SECTION, name = "max-sessions", example = "8")
public int maxSessions = DEFAULT_MAX_SESSIONS;
@Parameter(
names = {"--override-max-sessions"},
arity = 1,
description = "The # of available processos is the recommended max sessions value (1 browser "
+ "session per processor). Setting this flag to true allows the recommended max "
+ "value to be overwritten. Session stability and reliability might suffer as "
+ "the host could run out of resources.")
@ConfigValue(section = NODE_SECTION, name = "override-max-sessions", example = "false")
public Boolean overrideMaxSessions = OVERRIDE_MAX_SESSIONS;
@Parameter(
names = {"--session-timeout"},
description = "Let X be the session-timeout in seconds. The Node will automatically kill "
+ "a session that has not had any activity in the last X seconds. " +
"This will release the slot for other tests.")
@ConfigValue(section = NODE_SECTION, name = "session-timeout", example = "60")
public int sessionTimeout = DEFAULT_SESSION_TIMEOUT;
@Parameter(
names = {"--detect-drivers"}, arity = 1,
description = "Autodetect which drivers are available on the current system, " +
"and add them to the Node.")
@ConfigValue(section = NODE_SECTION, name = "detect-drivers", example = "true")
public Boolean autoconfigure = DEFAULT_DETECT_DRIVERS;
@Parameter(
names = {"-I", "--driver-implementation"},
description = "Drivers that should be checked. If specified, will skip autoconfiguration. " +
"Example: -I \"firefox\" -I \"chrome\"")
@ConfigValue(
section = NODE_SECTION,
name = "driver-implementation",
example = "[\"firefox\", \"chrome\"]")
public Set<String> driverNames = new HashSet<>();
@Parameter(
names = {"--driver-factory"},
description = "Mapping of fully qualified class name to a browser configuration that this " +
"matches against. " +
"--driver-factory org.openqa.selenium.example.LynxDriverFactory " +
"'{\"browserName\": \"lynx\"}'",
arity = 2,
variableArity = true,
splitter = NonSplittingSplitter.class)
@ConfigValue(
section = NODE_SECTION,
name = "driver-factories",
example = "[\"org.openqa.selenium.example.LynxDriverFactory '{\"browserName\": \"lynx\"}']")
public List<String> driverFactory2Config;
@Parameter(
names = {"--grid-url"},
description = "Public URL of the Grid as a whole (typically the address of the Hub " +
"or the Router)")
@ConfigValue(section = NODE_SECTION, name = "grid-url", example = "\"https://grid.example.com\"")
public String gridUri;
@Parameter(
names = {"--driver-configuration"},
description = "List of configured drivers a Node supports. " +
"It is recommended to provide this type of configuration through a toml config " +
"file to improve readability. Command line example: " +
"--drivers-configuration name=\"Firefox Nightly\" max-sessions=2 " +
"stereotype='{\"browserName\": \"firefox\", \"browserVersion\": \"86\", " +
"\"moz:firefoxOptions\": " +
"{\"binary\":\"/Applications/Firefox Nightly.app/Contents/MacOS/firefox-bin\"}}'",
arity = 3,
variableArity = true,
splitter = NonSplittingSplitter.class)
@ConfigValue(
section = NODE_SECTION,
name = "driver-configuration",
prefixed = true,
example = "\n" +
"name = \"Firefox Nightly\"\n" +
"max-sessions = 2\n" +
"stereotype = \"{\"browserName\": \"firefox\", \"browserVersion\": \"86\", " +
"\"moz:firefoxOptions\": " +
"{\"binary\":\"/Applications/Firefox Nightly.app/Contents/MacOS/firefox-bin\"}}\"")
public List<String> driverConfiguration;
@Parameter(
names = "--register-cycle",
description = "How often, in seconds, the Node will try to register itself for "
+ "the first time to the Distributor.")
@ConfigValue(section = NODE_SECTION, name = "register-cycle", example = "10")
public int registerCycle = DEFAULT_REGISTER_CYCLE;
@Parameter(
names = "--register-period",
description = "How long, in seconds, will the Node try to register to the Distributor for " +
"the first time. After this period is completed, the Node will not attempt " +
"to register again.")
@ConfigValue(section = NODE_SECTION, name = "register-period", example = "120")
public int registerPeriod = DEFAULT_REGISTER_PERIOD;
@Parameter(
names = "--heartbeat-period",
description = "How often, in seconds, will the Node send heartbeat events to the Distributor " +
"to inform it that the Node is up.")
@ConfigValue(section = NODE_SECTION, name = "heartbeat-period", example = "10")
public int heartbeatPeriod = DEFAULT_HEARTBEAT_PERIOD;
@Override
public Set<Role> getRoles() {
return Collections.singleton(NODE_ROLE);
}
}
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package org.openqa.selenium.grid.node.local;
import com.google.common.collect.ImmutableList;
import org.openqa.selenium.Capabilities;
import org.openqa.selenium.WebDriverInfo;
import org.openqa.selenium.grid.config.Config;
import org.openqa.selenium.grid.docker.DockerOptions;
import org.openqa.selenium.grid.log.LoggingOptions;
import org.openqa.selenium.grid.node.Node;
import org.openqa.selenium.grid.node.SessionFactory;
import org.openqa.selenium.grid.node.config.DriverServiceSessionFactory;
import org.openqa.selenium.grid.node.config.NodeOptions;
import org.openqa.selenium.grid.server.BaseServerOptions;
import org.openqa.selenium.grid.server.EventBusOptions;
import org.openqa.selenium.grid.server.NetworkOptions;
import org.openqa.selenium.remote.http.HttpClient;
import org.openqa.selenium.remote.service.DriverService;
import org.openqa.selenium.remote.tracing.Tracer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.ServiceLoader;
public class LocalNodeFactory {
public static Node create(Config config) {
LoggingOptions loggingOptions = new LoggingOptions(config);
EventBusOptions eventOptions = new EventBusOptions(config);
BaseServerOptions serverOptions = new BaseServerOptions(config);
NodeOptions nodeOptions = new NodeOptions(config);
NetworkOptions networkOptions = new NetworkOptions(config);
Tracer tracer = loggingOptions.getTracer();
HttpClient.Factory clientFactory = networkOptions.getHttpClientFactory(tracer);
LocalNode.Builder builder = LocalNode.builder(
tracer,
eventOptions.getEventBus(),
serverOptions.getExternalUri(),
nodeOptions.getPublicGridUri().orElseGet(serverOptions::getExternalUri),
serverOptions.getRegistrationSecret());
List<DriverService.Builder<?, ?>> builders = new ArrayList<>();
ServiceLoader.load(DriverService.Builder.class).forEach(builders::add);
nodeOptions.getSessionFactories(info -> createSessionFactory(tracer, clientFactory, builders, info))
.forEach((caps, factories) -> factories.forEach(factory -> builder.add(caps, factory)));
new DockerOptions(config).getDockerSessionFactories(tracer, clientFactory)
.forEach((caps, factories) -> factories.forEach(factory -> builder.add(caps, factory)));
return builder.build();
}
private static Collection<SessionFactory> createSessionFactory(
Tracer tracer,
HttpClient.Factory clientFactory,
List<DriverService.Builder<?, ?>> builders,
WebDriverInfo info) {
ImmutableList.Builder<SessionFactory> toReturn = ImmutableList.builder();
Capabilities caps = info.getCanonicalCapabilities();
builders.stream()
.filter(builder -> builder.score(caps) > 0)
.forEach(builder -> {
DriverService.Builder<?, ?> freePortBuilder = builder.usingAnyFreePort();
toReturn.add(new DriverServiceSessionFactory(
tracer,
clientFactory,
info.getCanonicalCapabilities(),
c -> freePortBuilder.score(c) > 0,
freePortBuilder));
});
return toReturn.build();
}
}
public static void main(String[] args) {
List<Long> times = new ArrayList<>();
for (int i = 0; i < 100; i++) {
times.add(doIt());
}
System.out.println("avg = " + (times.stream().mapToLong(x -> x).average()));
}
static long doIt() {
long start = System.nanoTime();
List<Object> list = new LinkedList<>();
//uncomment line below to test with ArrayList
//list = new ArrayList<>();
for (int i = 0; i < 500; i++) {
list.add(i);
}
Iterator it = list.iterator();
while (it.hasNext()) {
it.next();
it.remove();
}
long end = System.nanoTime();
long diff = end - start;
//uncomment to see the JVM warmup and get faster for the first few iterations
//System.out.println(diff)
return diff;
}
get O(1)
add O(1)
contains O(n)
next O(1)
remove O(n)
iterator.remove O(n)
get O(n)
add O(1)
contains O(n)
next O(1)
remove O(1)
iterator.remove O(1)
get O(1)
add O(n)
contains O(n)
next O(1)
remove O(n)
iterator.remove O(n)
|---------------------|---------------------|--------------------|------------|
| Operation | ArrayList | LinkedList | Winner |
|---------------------|---------------------|--------------------|------------|
| get(index) | O(1) | O(n) | ArrayList |
| | | n/4 steps in avg | |
|---------------------|---------------------|--------------------|------------|
| add(E) | O(1) | O(1) | LinkedList |
| |---------------------|--------------------| |
| | O(n) in worst case | | |
|---------------------|---------------------|--------------------|------------|
| add(index, E) | O(n) | O(n) | LinkedList |
| | n/2 steps | n/4 steps | |
| |---------------------|--------------------| |
| | | O(1) if index = 0 | |
|---------------------|---------------------|--------------------|------------|
| remove(index, E) | O(n) | O(n) | LinkedList |
| |---------------------|--------------------| |
| | n/2 steps | n/4 steps | |
|---------------------|---------------------|--------------------|------------|
| Iterator.remove() | O(n) | O(1) | LinkedList |
| ListIterator.add() | | | |
|---------------------|---------------------|--------------------|------------|
|--------------------------------------|-----------------------------------|
| ArrayList | LinkedList |
|--------------------------------------|-----------------------------------|
| Allows fast read access | Retrieving element takes O(n) |
|--------------------------------------|-----------------------------------|
| Adding an element require shifting | o(1) [but traversing takes time] |
| all the later elements | |
|--------------------------------------|-----------------------------------|
| To add more elements than capacity |
| new array need to be allocated |
|--------------------------------------|
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
Read 1 MB sequentially from memory 250,000 ns 250 us
Round trip within same datacenter 500,000 ns 500 us
Read 1 MB sequentially from SSD* 1,000,000 ns 1,000 us 1 ms ~1GB/sec SSD, 4X memory
Disk seek 10,000,000 ns 10,000 us 10 ms 20x datacenter roundtrip
Read 1 MB sequentially from disk 20,000,000 ns 20,000 us 20 ms 80x memory, 20X SSD
Send packet CA->Netherlands->CA 150,000,000 ns 150,000 us 150 ms
Operation ArrayList LinkedList
AddAll (Insert) 101,16719 2623,29291
Add (Insert-Sequentially) 152,46840 966,62216
Add (insert-randomly) 36527 29193
remove (Delete) 20,56,9095 20,45,4904
contains (Search) 186,15,704 189,64,981
import org.junit.Assert;
import org.junit.Test;
import java.util.*;
public class ArrayListVsLinkedList {
private static final int MAX = 500000;
String[] strings = maxArray();
////////////// ADD ALL ////////////////////////////////////////
@Test
public void arrayListAddAll() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
watch.start();
arrayList.addAll(stringList);
watch.totalTime("Array List addAll() = ");//101,16719 Nanoseconds
}
@Test
public void linkedListAddAll() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
watch.start();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(stringList);
watch.totalTime("Linked List addAll() = "); //2623,29291 Nanoseconds
}
//Note: ArrayList is 26 time faster here than LinkedList for addAll()
///////////////// INSERT /////////////////////////////////////////////
@Test
public void arrayListAdd() {
Watch watch = new Watch();
List<String> arrayList = new ArrayList<String>(MAX);
watch.start();
for (String string : strings)
arrayList.add(string);
watch.totalTime("Array List add() = ");//152,46840 Nanoseconds
}
@Test
public void linkedListAdd() {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
watch.start();
for (String string : strings)
linkedList.add(string);
watch.totalTime("Linked List add() = "); //966,62216 Nanoseconds
}
//Note: ArrayList is 9 times faster than LinkedList for add sequentially
/////////////////// INSERT IN BETWEEN ///////////////////////////////////////
@Test
public void arrayListInsertOne() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX + MAX / 10);
arrayList.addAll(stringList);
String insertString0 = getString(true, MAX / 2 + 10);
String insertString1 = getString(true, MAX / 2 + 20);
String insertString2 = getString(true, MAX / 2 + 30);
String insertString3 = getString(true, MAX / 2 + 40);
watch.start();
arrayList.add(insertString0);
arrayList.add(insertString1);
arrayList.add(insertString2);
arrayList.add(insertString3);
watch.totalTime("Array List add() = ");//36527
}
@Test
public void linkedListInsertOne() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(stringList);
String insertString0 = getString(true, MAX / 2 + 10);
String insertString1 = getString(true, MAX / 2 + 20);
String insertString2 = getString(true, MAX / 2 + 30);
String insertString3 = getString(true, MAX / 2 + 40);
watch.start();
linkedList.add(insertString0);
linkedList.add(insertString1);
linkedList.add(insertString2);
linkedList.add(insertString3);
watch.totalTime("Linked List add = ");//29193
}
//Note: LinkedList is 3000 nanosecond faster than ArrayList for insert randomly.
////////////////// DELETE //////////////////////////////////////////////////////
@Test
public void arrayListRemove() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
arrayList.addAll(stringList);
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
arrayList.remove(searchString0);
arrayList.remove(searchString1);
watch.totalTime("Array List remove() = ");//20,56,9095 Nanoseconds
}
@Test
public void linkedListRemove() throws Exception {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(Arrays.asList(strings));
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
linkedList.remove(searchString0);
linkedList.remove(searchString1);
watch.totalTime("Linked List remove = ");//20,45,4904 Nanoseconds
}
//Note: LinkedList is 10 millisecond faster than ArrayList while removing item.
///////////////////// SEARCH ///////////////////////////////////////////
@Test
public void arrayListSearch() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
arrayList.addAll(stringList);
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
arrayList.contains(searchString0);
arrayList.contains(searchString1);
watch.totalTime("Array List addAll() time = ");//186,15,704
}
@Test
public void linkedListSearch() throws Exception {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(Arrays.asList(strings));
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
linkedList.contains(searchString0);
linkedList.contains(searchString1);
watch.totalTime("Linked List addAll() time = ");//189,64,981
}
//Note: Linked List is 500 Milliseconds faster than ArrayList
class Watch {
private long startTime;
private long endTime;
public void start() {
startTime = System.nanoTime();
}
private void stop() {
endTime = System.nanoTime();
}
public void totalTime(String s) {
stop();
System.out.println(s + (endTime - startTime));
}
}
private String[] maxArray() {
String[] strings = new String[MAX];
Boolean result = Boolean.TRUE;
for (int i = 0; i < MAX; i++) {
strings[i] = getString(result, i);
result = !result;
}
return strings;
}
private String getString(Boolean result, int i) {
return String.valueOf(result) + i + String.valueOf(!result);
}
}
Algorithm ArrayList LinkedList
seek front O(1) O(1)
seek back O(1) O(1)
seek to index O(1) O(N)
insert at front O(N) O(1)
insert at back O(1) O(1)
insert after an item O(N) O(1)
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<bytecodeTargetLevel>
<module name="your_project_name_main" target="1.8" />
<module name="your_project_name_test" target="1.8" />
</bytecodeTargetLevel>
android {
compileOptions {
...
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
...
}
}
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<project>
[...]
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
[...]
</project>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<!-- ... -->
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<!-- ... -->
</project>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
// CPP program to demonstrate processing
// time of sorted and unsorted array
#include <iostream>
#include <algorithm>
#include <ctime>
using namespace std;
const int N = 100001;
int main()
{
int arr[N];
// Assign random values to array
for (int i=0; i<N; i++)
arr[i] = rand()%N;
// for loop for unsorted array
int count = 0;
double start = clock();
for (int i=0; i<N; i++)
if (arr[i] < N/2)
count++;
double end = clock();
cout << "Time for unsorted array :: "
<< ((end - start)/CLOCKS_PER_SEC)
<< endl;
sort(arr, arr+N);
// for loop for sorted array
count = 0;
start = clock();
for (int i=0; i<N; i++)
if (arr[i] < N/2)
count++;
end = clock();
cout << "Time for sorted array :: "
<< ((end - start)/CLOCKS_PER_SEC)
<< endl;
return 0;
}
Already sorted 32995 milliseconds
Shuffled 125944 milliseconds
Already sorted 18610 milliseconds
Shuffled 133304 milliseconds
Already sorted 17942 milliseconds
Shuffled 107858 milliseconds
void run(vector<int>& v, const string& label)
{
auto t0 = system_clock::now();
sort(v.begin(), v.end());
auto t1 = system_clock::now();
cout << label
<< duration_cast<microseconds>(t1 — t0).count()
<< " milliseconds\n";
}
void tst()
{
vector<int> v(1'000'000);
iota(v.begin(), v.end(), 0);
run(v, "already sorted ");
std::shuffle(v.begin(), v.end(), std::mt19937{ std::random_device{}() });
run(v, "shuffled ");
}
#include <algorithm>
#include <ctime>
#include <iostream>
int main() {
int data[32768]; const int l = sizeof data / sizeof data[0];
for (unsigned c = 0; c < l; ++c)
data[c] = std::rand() % 256;
// sort 200-element segments, not the whole array
for (unsigned c = 0; c + 200 <= l; c += 200)
std::sort(&data[c], &data[c + 200]);
clock_t start = clock();
long long sum = 0;
for (unsigned i = 0; i < 100000; ++i) {
for (unsigned c = 0; c < sizeof data / sizeof(int); ++c) {
if (data[c] >= 128)
sum += data[c];
}
}
std::cout << static_cast<double>(clock() - start) / CLOCKS_PER_SEC << std::endl;
std::cout << "sum = " << sum << std::endl;
}
% Processing time with Sorted data vs unsorted data
%==========================================================================
% Generate data
arraySize = 32768
sum = 0;
% Generate random integer data from range 0 to 255
data = randi(256, arraySize, 1);
%Sort the data
data1= sort(data); % data1= data when no sorting done
%Start a stopwatch timer to measure the execution time
tic;
for i=1:100000
for j=1:arraySize
if data1(j)>=128
sum=sum + data1(j);
end
end
end
toc;
ExeTimeWithSorting = toc - tic;
a: Elapsed time (without sorting) = 3479.880861 seconds.
b: Elapsed time (with sorting ) = 2377.873098 seconds.
a: Elapsed time (without sorting) = 19.8761 sec.
b: Elapsed time (with sorting ) = 7.37778 sec.
____________________________________________________________________________________
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
___________________________________________ Straight road
|_________________________________________|Longer road
// sort backwards (higher values first), may be in some other part of the code
std::sort(data, data + arraySize, std::greater<int>());
for (unsigned c = 0; c < arraySize; ++c) {
if (data[c] < 128) {
break;
}
sum += data[c];
}
MOV R0, #0 // R0 = sum = 0
MOV R1, #0 // R1 = c = 0
ADR R2, data // R2 = addr of data array (put this instruction outside outer loop)
.inner_loop // Inner loop branch label
LDRB R3, [R2, R1] // R3 = data[c]
CMP R3, #128 // compare R3 to 128
ADDGE R0, R0, R3 // if R3 >= 128, then sum += data[c] -- no branch needed!
ADD R1, R1, #1 // c++
CMP R1, #arraySize // compare c to arraySize
BLT inner_loop // Branch to inner_loop if c < arraySize
if (expression)
{
// Run 1
} else {
// Run 2
}
O Route 1 /-------------------------------
/|\ /
| ---------##/
/ \ \
\
Route 2 \--------------------------------
bool a, b, c, d;
c = a && b;
d = a || b;
bool a, b, c, d;
if (a != 0) {
if (b != 0) {
c = 1;
}
else {
goto CFALSE;
}
}
else {
CFALSE:
c = 0;
}
if (a == 0) {
if (b == 0) {
d = 0;
}
else {
goto DTRUE;
}
}
else {
DTRUE:
d = 1;
}
char a = 0, b = 1, c, d;
c = a & b;
d = a | b;
char a = 0, b;
b = a ^ 1;
bool a; double x, y, z;
a = x > y && z < 5.0;
if (likely( everything_is_ok ))
{
/* Do something */
}
if (unlikely(very_improbable_condition))
{
/* Do something */
}
data[c] = std::rand() % 256;
A) if (data[c] >= 128)
/\
/ \
/ \
true / \ false
/ \
/ \
/ \
/ \
B) sum += data[c]; C) for loop or print().
int i= 0, j, k= arraySize;
while (i < k)
{
j= (i + k) >> 1;
if (data[j] >= 128)
k= j;
else
i= j;
}
sum= 0;
for (; i < arraySize; i++)
sum+= data[i];
int i, k, j= (i + k) >> 1;
for (i= 0, k= arraySize; i < k; (data[j] >= 128 ? k : i)= j)
j= (i + k) >> 1;
for (sum= 0; i < arraySize; i++)
sum+= data[i];
// Test
clock_t start = clock();
long long a[] = {0, 0};
long long sum;
for (unsigned i = 0; i < 100000; ++i)
{
// Primary loop
for (unsigned c = 0; c < arraySize; ++c)
{
int j = (data[c] >> 7);
a[j] += data[c];
}
}
double elapsedTime = static_cast<double>(clock() - start) / CLOCKS_PER_SEC;
sum = a[1];
// Declare and then fill in the lookup table
int lut[256];
for (unsigned c = 0; c < 256; ++c)
lut[c] = (c >= 128) ? c : 0;
// Use the lookup table after it is built
for (unsigned i = 0; i < 100000; ++i)
{
// Primary loop
for (unsigned c = 0; c < arraySize; ++c)
{
sum += lut[data[c]];
}
}
if (x < node->value)
node = node->pLeft;
else
node = node->pRight;
i = (x < node->value);
node = node->link[i];
if (data[c] >= 128)
sum += data[c];
for (int i = 0; i < max; i++)
if (condition)
sum++;
Condition Pattern Time (ms)
-------------------------------------------------------
(i & 0×80000000) == 0 T repeated 322
(i & 0xffffffff) == 0 F repeated 276
(i & 1) == 0 TF alternating 760
(i & 3) == 0 TFFFTFFF… 513
(i & 2) == 0 TTFFTTFF… 1675
(i & 4) == 0 TTTTFFFFTTTTFFFF… 1275
(i & 8) == 0 8T 8F 8T 8F … 752
(i & 16) == 0 16T 16F 16T 16F … 490
for (int i = 0; i < array.Length; ++i)
{
// Use array[i]
}
// Generate data
int arraySize = 32768;
int[] data = new int[arraySize];
Random random = new Random(0);
for (int c = 0; c < arraySize; ++c)
{
data[c] = random.Next(256);
}
/*To keep the spirit of the code intact, I'll make a separate lookup table
(I assume we cannot modify 'data' or the number of loops)*/
int[] lookup = new int[256];
for (int c = 0; c < 256; ++c)
{
lookup[c] = (c >= 128) ? c : 0;
}
// Test
DateTime startTime = System.DateTime.Now;
long sum = 0;
for (int i = 0; i < 100000; ++i)
{
// Primary loop
for (int j = 0; j < arraySize; ++j)
{
/* Here you basically want to use simple operations - so no
random branches, but things like &, |, *, -, +, etc. are fine. */
sum += lookup[data[j]];
}
}
DateTime endTime = System.DateTime.Now;
Console.WriteLine(endTime - startTime);
Console.WriteLine("sum = " + sum);
Console.ReadLine();
==32551== Branches: 656,645,130 ( 656,609,208 cond + 35,922 ind)
==32551== Mispredicts: 169,556 ( 169,095 cond + 461 ind)
==32551== Mispred rate: 0.0% ( 0.0% + 1.2% )
==32555== Branches: 655,996,082 ( 655,960,160 cond + 35,922 ind)
==32555== Mispredicts: 164,073,152 ( 164,072,692 cond + 460 ind)
==32555== Mispred rate: 25.0% ( 25.0% + 1.2% )
Bc Bcm Bi Bim
10,001 4 0 0 for (unsigned i = 0; i < 10000; ++i)
. . . . {
. . . . // primary loop
327,690,000 10,016 0 0 for (unsigned c = 0; c < arraySize; ++c)
. . . . {
327,680,000 10,006 0 0 if (data[c] >= 128)
0 0 0 0 sum += data[c];
. . . . }
. . . . }
Bc Bcm Bi Bim
10,001 4 0 0 for (unsigned i = 0; i < 10000; ++i)
. . . . {
. . . . // primary loop
327,690,000 10,038 0 0 for (unsigned c = 0; c < arraySize; ++c)
. . . . {
327,680,000 164,050,007 0 0 if (data[c] >= 128)
0 0 0 0 sum += data[c];
. . . . }
. . . . }
perf stat ./sumtest_sorted
Performance counter stats for './sumtest_sorted':
11808.095776 task-clock # 0.998 CPUs utilized
1,062 context-switches # 0.090 K/sec
14 CPU-migrations # 0.001 K/sec
337 page-faults # 0.029 K/sec
26,487,882,764 cycles # 2.243 GHz
41,025,654,322 instructions # 1.55 insns per cycle
6,558,871,379 branches # 555.455 M/sec
567,204 branch-misses # 0.01% of all branches
11.827228330 seconds time elapsed
Performance counter stats for './sumtest_unsorted':
28877.954344 task-clock # 0.998 CPUs utilized
2,584 context-switches # 0.089 K/sec
18 CPU-migrations # 0.001 K/sec
335 page-faults # 0.012 K/sec
65,076,127,595 cycles # 2.253 GHz
41,032,528,741 instructions # 0.63 insns per cycle
6,560,579,013 branches # 227.183 M/sec
1,646,394,749 branch-misses # 25.10% of all branches
28.935500947 seconds time elapsed
perf record -e branch-misses ./sumtest_unsorted
perf annotate -d sumtest_unsorted
Percent | Source code & Disassembly of sumtest_unsorted
------------------------------------------------
...
: sum += data[c];
0.00 : 400a1a: mov -0x14(%rbp),%eax
39.97 : 400a1d: mov %eax,%eax
5.31 : 400a1f: mov -0x20040(%rbp,%rax,4),%eax
4.60 : 400a26: cltq
0.00 : 400a28: add %rax,-0x30(%rbp)
...
for (unsigned i = 0; i < 100000; ++i)
{
for (unsigned j = 0; j < arraySize; ++j)
{
if (data[j] >= 128)
sum += data[j];
}
}
for (unsigned j = 0; j < arraySize; ++j)
{
for (unsigned i = 0; i < 100000; ++i)
{
if (data[j] >= 128)
sum += data[j];
}
}
for (unsigned j = 0; j < arraySize; ++j)
{
if (data[j] >= 128)
{
for (unsigned i = 0; i < 100000; ++i)
{
sum += data[j];
}
}
}
for (unsigned j = 0; j < arraySize; ++j)
{
if (data[j] >= 128)
{
sum += data[j] * 100000;
}
}
if (data[c] >= 128)
sum += data[c];
sum += data[c] >=128 ? data[c] : 0;
int max1(int a, int b) {
if (a > b)
return a;
else
return b;
}
int max2(int a, int b) {
return a > b ? a : b;
}
:max1
movl %edi, -4(%rbp)
movl %esi, -8(%rbp)
movl -4(%rbp), %eax
cmpl -8(%rbp), %eax
jle .L2
movl -4(%rbp), %eax
movl %eax, -12(%rbp)
jmp .L4
.L2:
movl -8(%rbp), %eax
movl %eax, -12(%rbp)
.L4:
movl -12(%rbp), %eax
leave
ret
:max2
movl %edi, -4(%rbp)
movl %esi, -8(%rbp)
movl -4(%rbp), %eax
cmpl %eax, -8(%rbp)
cmovge -8(%rbp), %eax
leave
ret
if (data[c] >= 128)
sum += data[c];
T = branch taken
N = branch not taken
data[] = 0, 1, 2, 3, 4, ... 126, 127, 128, 129, 130, ... 250, 251, 252, ...
branch = N N N N N ... N N T T T ... T T T ...
= NNNNNNNNNNNN ... NNNNNNNTTTTTTTTT ... TTTTTTTTTT (easy to predict)
data[] = 226, 185, 125, 158, 198, 144, 217, 79, 202, 118, 14, 150, 177, 182, ...
branch = T, T, N, T, T, T, T, N, T, N, N, T, T, T ...
= TTNTTTTNTNNTTT ... (completely random - impossible to predict)
if (data[c] >= 128)
sum += data[c];
int t = (data[c] - 128) >> 31;
sum += ~t & data[c];
public static void main(String[] args) {
List<Long> times = new ArrayList<>();
for (int i = 0; i < 100; i++) {
times.add(doIt());
}
System.out.println("avg = " + (times.stream().mapToLong(x -> x).average()));
}
static long doIt() {
long start = System.nanoTime();
List<Object> list = new LinkedList<>();
//uncomment line below to test with ArrayList
//list = new ArrayList<>();
for (int i = 0; i < 500; i++) {
list.add(i);
}
Iterator it = list.iterator();
while (it.hasNext()) {
it.next();
it.remove();
}
long end = System.nanoTime();
long diff = end - start;
//uncomment to see the JVM warmup and get faster for the first few iterations
//System.out.println(diff)
return diff;
}
get O(1)
add O(1)
contains O(n)
next O(1)
remove O(n)
iterator.remove O(n)
get O(n)
add O(1)
contains O(n)
next O(1)
remove O(1)
iterator.remove O(1)
get O(1)
add O(n)
contains O(n)
next O(1)
remove O(n)
iterator.remove O(n)
|---------------------|---------------------|--------------------|------------|
| Operation | ArrayList | LinkedList | Winner |
|---------------------|---------------------|--------------------|------------|
| get(index) | O(1) | O(n) | ArrayList |
| | | n/4 steps in avg | |
|---------------------|---------------------|--------------------|------------|
| add(E) | O(1) | O(1) | LinkedList |
| |---------------------|--------------------| |
| | O(n) in worst case | | |
|---------------------|---------------------|--------------------|------------|
| add(index, E) | O(n) | O(n) | LinkedList |
| | n/2 steps | n/4 steps | |
| |---------------------|--------------------| |
| | | O(1) if index = 0 | |
|---------------------|---------------------|--------------------|------------|
| remove(index, E) | O(n) | O(n) | LinkedList |
| |---------------------|--------------------| |
| | n/2 steps | n/4 steps | |
|---------------------|---------------------|--------------------|------------|
| Iterator.remove() | O(n) | O(1) | LinkedList |
| ListIterator.add() | | | |
|---------------------|---------------------|--------------------|------------|
|--------------------------------------|-----------------------------------|
| ArrayList | LinkedList |
|--------------------------------------|-----------------------------------|
| Allows fast read access | Retrieving element takes O(n) |
|--------------------------------------|-----------------------------------|
| Adding an element require shifting | o(1) [but traversing takes time] |
| all the later elements | |
|--------------------------------------|-----------------------------------|
| To add more elements than capacity |
| new array need to be allocated |
|--------------------------------------|
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD
Read 1 MB sequentially from memory 250,000 ns 250 us
Round trip within same datacenter 500,000 ns 500 us
Read 1 MB sequentially from SSD* 1,000,000 ns 1,000 us 1 ms ~1GB/sec SSD, 4X memory
Disk seek 10,000,000 ns 10,000 us 10 ms 20x datacenter roundtrip
Read 1 MB sequentially from disk 20,000,000 ns 20,000 us 20 ms 80x memory, 20X SSD
Send packet CA->Netherlands->CA 150,000,000 ns 150,000 us 150 ms
Operation ArrayList LinkedList
AddAll (Insert) 101,16719 2623,29291
Add (Insert-Sequentially) 152,46840 966,62216
Add (insert-randomly) 36527 29193
remove (Delete) 20,56,9095 20,45,4904
contains (Search) 186,15,704 189,64,981
import org.junit.Assert;
import org.junit.Test;
import java.util.*;
public class ArrayListVsLinkedList {
private static final int MAX = 500000;
String[] strings = maxArray();
////////////// ADD ALL ////////////////////////////////////////
@Test
public void arrayListAddAll() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
watch.start();
arrayList.addAll(stringList);
watch.totalTime("Array List addAll() = ");//101,16719 Nanoseconds
}
@Test
public void linkedListAddAll() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
watch.start();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(stringList);
watch.totalTime("Linked List addAll() = "); //2623,29291 Nanoseconds
}
//Note: ArrayList is 26 time faster here than LinkedList for addAll()
///////////////// INSERT /////////////////////////////////////////////
@Test
public void arrayListAdd() {
Watch watch = new Watch();
List<String> arrayList = new ArrayList<String>(MAX);
watch.start();
for (String string : strings)
arrayList.add(string);
watch.totalTime("Array List add() = ");//152,46840 Nanoseconds
}
@Test
public void linkedListAdd() {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
watch.start();
for (String string : strings)
linkedList.add(string);
watch.totalTime("Linked List add() = "); //966,62216 Nanoseconds
}
//Note: ArrayList is 9 times faster than LinkedList for add sequentially
/////////////////// INSERT IN BETWEEN ///////////////////////////////////////
@Test
public void arrayListInsertOne() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX + MAX / 10);
arrayList.addAll(stringList);
String insertString0 = getString(true, MAX / 2 + 10);
String insertString1 = getString(true, MAX / 2 + 20);
String insertString2 = getString(true, MAX / 2 + 30);
String insertString3 = getString(true, MAX / 2 + 40);
watch.start();
arrayList.add(insertString0);
arrayList.add(insertString1);
arrayList.add(insertString2);
arrayList.add(insertString3);
watch.totalTime("Array List add() = ");//36527
}
@Test
public void linkedListInsertOne() {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(stringList);
String insertString0 = getString(true, MAX / 2 + 10);
String insertString1 = getString(true, MAX / 2 + 20);
String insertString2 = getString(true, MAX / 2 + 30);
String insertString3 = getString(true, MAX / 2 + 40);
watch.start();
linkedList.add(insertString0);
linkedList.add(insertString1);
linkedList.add(insertString2);
linkedList.add(insertString3);
watch.totalTime("Linked List add = ");//29193
}
//Note: LinkedList is 3000 nanosecond faster than ArrayList for insert randomly.
////////////////// DELETE //////////////////////////////////////////////////////
@Test
public void arrayListRemove() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
arrayList.addAll(stringList);
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
arrayList.remove(searchString0);
arrayList.remove(searchString1);
watch.totalTime("Array List remove() = ");//20,56,9095 Nanoseconds
}
@Test
public void linkedListRemove() throws Exception {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(Arrays.asList(strings));
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
linkedList.remove(searchString0);
linkedList.remove(searchString1);
watch.totalTime("Linked List remove = ");//20,45,4904 Nanoseconds
}
//Note: LinkedList is 10 millisecond faster than ArrayList while removing item.
///////////////////// SEARCH ///////////////////////////////////////////
@Test
public void arrayListSearch() throws Exception {
Watch watch = new Watch();
List<String> stringList = Arrays.asList(strings);
List<String> arrayList = new ArrayList<String>(MAX);
arrayList.addAll(stringList);
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
arrayList.contains(searchString0);
arrayList.contains(searchString1);
watch.totalTime("Array List addAll() time = ");//186,15,704
}
@Test
public void linkedListSearch() throws Exception {
Watch watch = new Watch();
List<String> linkedList = new LinkedList<String>();
linkedList.addAll(Arrays.asList(strings));
String searchString0 = getString(true, MAX / 2 + 10);
String searchString1 = getString(true, MAX / 2 + 20);
watch.start();
linkedList.contains(searchString0);
linkedList.contains(searchString1);
watch.totalTime("Linked List addAll() time = ");//189,64,981
}
//Note: Linked List is 500 Milliseconds faster than ArrayList
class Watch {
private long startTime;
private long endTime;
public void start() {
startTime = System.nanoTime();
}
private void stop() {
endTime = System.nanoTime();
}
public void totalTime(String s) {
stop();
System.out.println(s + (endTime - startTime));
}
}
private String[] maxArray() {
String[] strings = new String[MAX];
Boolean result = Boolean.TRUE;
for (int i = 0; i < MAX; i++) {
strings[i] = getString(result, i);
result = !result;
}
return strings;
}
private String getString(Boolean result, int i) {
return String.valueOf(result) + i + String.valueOf(!result);
}
}
Algorithm ArrayList LinkedList
seek front O(1) O(1)
seek back O(1) O(1)
seek to index O(1) O(N)
insert at front O(N) O(1)
insert at back O(1) O(1)
insert after an item O(N) O(1)
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<bytecodeTargetLevel>
<module name="your_project_name_main" target="1.8" />
<module name="your_project_name_test" target="1.8" />
</bytecodeTargetLevel>
android {
compileOptions {
...
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
...
}
}
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<project>
[...]
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
[...]
</project>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<!-- ... -->
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<!-- ... -->
</project>
