CS计算机代考程序代写 Java distributed system COMP3221 Lab 1 Multithreading
COMP3221 Lab 1 Multithreading
The goal of the lab is to understand how Java threads work.
Note that you can use Windows, but some labs will require the use of Linux later on. You are also allowed to use eclipse or any integrated development enrivonment (IDE) like eclipse or netbeans but you are expected to know how to use javac and java on the command line to compile and run your programs.
Exercise 1: Java threads
We will run a thread by creating a class that implements the Runnable interface. To prepare a Java thread for execution: (1) implements the Runnable interface, (2) allocate a new thread, and (3) starts it. Below is an example:
// (1) implement the Runnable interface
class MyThread implements Runnable { public void run() {
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/* here goes my thread code */
public static void main(String args[]) {
Thread mt = new Thread(new MyThread());// (2) allocate a new thread mt.start(); // (3) start it
Based on the code snippet above create a java class that starts one thread which outputs “hello world” on the standard output. (Preferably use javac to compile the .java files into bytecode and java to run the obtained class file.)
Duration: 10 min
Exercise 2: Vector-based producer consumer
Now that you know how to spawn threads, you will implement two communicating threads, a producer and a consumer. They communicate by enqueuing and dequeuing messages from a communication channel. The producer and the consumer will be written in files Producer.java and Consumer.java, respectively.
The code that spans the thread is located in file Factory.java, as indicated below: 1
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1 import java.util.Date; 2
3 public class Factory {
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public static void main(String args[]) {
// create the message queue
Channel
// create the producer and consumer threads and pass // each thread a reference to the MessageQueue object. Thread producer = new Thread(new Producer(queue)); Thread consumer = new Thread(new Consumer(queue));
producer.start(); consumer.start();
Finally,
and the
http://poseidon.it.usyd.edu.au/~gramoli/web/doc/ens/2-multithreading/ and placed in the same directory as the other files. Note that this communication channel consists of a Vector storing the messages.
Both the producer and the consumer execute an infinite loop. In each of its iterations, the producer waits 0.5 second before sending a new Date message and printing a successful message containing the sent date on the standard output. In each iteration, the consumer waits 0.5 second before receiving the earliest pending message and printing a successful message containing the received date on the standard output.
Duration: 30 min
Exercise 3: Thread-safety
The producer and consumer access the same MessageQueue concurrently. Find the documentation of java.util.Vector by browsing the Java API at http://docs.oracle.com/javase/8/docs/api/. Why is the producer consumer imple- mentation thread-safe? What happens if you replace Vector by an ArrayList (read the documentation)?
Duration: 10 min
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the implementation of the class MessageQueue.java
channel should
interface
be downloaded from
COMP3221 Multithreading
Channel.java
Distributed Systems Page 2 of 2
