Consider the BadReaderWriter.java program attached with this homework. The program has three threads, namely, one reader thread and two writer threads, and they all access the same list of numbers. The reader thread reads the list and prints it to the terminal. The writer threads append numbers to the list. At any point in time, if either of the writer threads finds that the list contains n elements, then it appends the number n + 1 to the list. Run this program, examine the output, and identify the problems. Fix these problems by implementing the acquireLock() and releaseLock() methods in the code.
Consider the BadReaderWriter.java program attached with this homework. The program has three threads, namely, one reader thread and two writer threads, and they all access the same list of numbers. The reader thread reads the list and prints it to the terminal. The writer threads append numbers to the list. At any point in time, if either of the writer threads finds that the list contains n elements, then it appends the number n + 1 to the list. Run this program, examine the output, and identify the problems. Fix these problems by implementing the acquireLock() and releaseLock() methods in the code.
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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Question
Consider the BadReaderWriter.java program attached with this homework. The program has three threads, namely, one reader thread and two writer threads, and they all access the same list of numbers. The reader thread reads the list and prints it to the terminal. The writer threads append numbers to the list. At any point in time, if either of the writer threads finds that the list contains n elements, then it appends the number n + 1 to the list.
Run this program, examine the output, and identify the problems.
Fix these problems by implementing the acquireLock() and releaseLock() methods in the code.
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1 import java.util.ArrayList;
2
3 public class BadReaderwriter {
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private static void acquireLock() throws InterruptedException {
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// TODO: Add code for acquiring lock for critical section
}
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private static void releaseLock() throws InterruptedException {
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// TODO: Add code for releasing lock for critical section
}
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static class ReaderThread extends Thread {
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String name = "";
ArrayList<Integer> numbers;
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ReaderThread (String name, ArrayList<Integer> numbers) {
this.name = name;
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this.numbers = numbers;
}
public void run() {
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for (int count = 0; count < 20; count++) {
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try {
acquirelock();
try {
System.out.println(">>>
System.out.flush();
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+ name + " read:
+ numbers);
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finally {
releaselock();
}
} catch (InterruptedException e) {
e.printstackTrace();
}
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}
}
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}
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static class WriterThread extends Thread {
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String name = "";
ArrayList<Integer> numbers;
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WriterThread(String name, ArrayList<Integer> numbers) {
this.name = name;
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this.numberS = numbers;
}
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public void run() {
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}
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}
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static class WriterThread extends Thread {
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String name =
ArrayList<Integer> numbers;
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WriterThread(String name, ArrayList<Integer> numbers) {
this.name = name;
this.numbers = numbers;
}
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public void run() {
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for (int count = 0; count < 10; count++) {
try {
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acquirelock();
try {
Integer entry = numbers.size() + 1;
numbers.add(entry);
System.out.println(">>>
System.out.flush();
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" added: "
+ entry);
+ name +
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}
finally {
releaselock(O;
}
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} catch (InterruptedException e) {
e.printstackTrace();
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}
}
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public static void main(String[] args) {
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ArrayList<Integer> list0fNumbers = new ArrayList<Integer>();
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ReaderThread t1 = new ReaderThread("reader1", listofNumbers);
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WriterThread t2 = new WriterThread ("writer1", listofNumbers);
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WriterThread t3 = new WriterThread("writer2", list0fNumbers);
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t1.start();
t2.start();
t3.start();
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}
95 }
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}
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}
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static class WriterThread extends Thread {
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String name =
ArrayList<Integer> numbers;
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WriterThread(String name, ArrayList<Integer> numbers) {
this.name = name;
this.numbers = numbers;
}
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public void run() {
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for (int count = 0; count < 10; count++) {
try {
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acquirelock();
try {
Integer entry = numbers.size() + 1;
numbers.add(entry);
System.out.println(">>>
System.out.flush();
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" added: "
+ entry);
+ name +
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}
finally {
releaselock(O;
}
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} catch (InterruptedException e) {
e.printstackTrace();
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}
}
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public static void main(String[] args) {
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ArrayList<Integer> list0fNumbers = new ArrayList<Integer>();
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ReaderThread t1 = new ReaderThread("reader1", listofNumbers);
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WriterThread t2 = new WriterThread ("writer1", listofNumbers);
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WriterThread t3 = new WriterThread("writer2", list0fNumbers);
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t1.start();
t2.start();
t3.start();
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}
95 }
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