Java Concurrency Lab Extend ThreadJava ConcurrencyLab Extend ThreadPresenter NameAgenda9/3/20XXWhat is the Thread ClassExtending the Thread Class Simple ExamplePresentation...

for the extend thread lab the question is on the end of the power point slide 14 & 15


Java Concurrency Lab Extend Thread Java Concurrency Lab Extend Thread Presenter Name Agenda 9/3/20XX What is the Thread Class Extending the Thread Class Simple Example Presentation Title 2 Introduction A thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. Presentation Title 3 Introduction A single java process can have many threads. The main process can spawn thread, or a thread can spawn a new thread! Presentation Title 4 Introduction We can define a thread in the following two ways: By extending Thread class By implementing Runnable interface 5 Thread Thread (Class) Runnable (Interface) run() method Override Extends Implements When to extending the thread class In General, you would rarely need to do this. Extending the Thread class is reserved for creating new thread functionality. If I need to change how a thread does something which given the nature of this, it would be fraught with danger. Presentation Title 6 Thread Class Thread a line of execution within a program. Each program can have multiple associated threads. Each thread has a priority which is used by the thread scheduler to determine which thread must run first. Java provides a thread class that has various method calls in order to manage the behavior of threads by providing constructors and methods to perform operations on threads. Presentation Title 7 Thread.sleep() Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers. The thread does not lose ownership of any monitors.(Don’t worry about this yet) 8 join() The join() method which allows one thread to wait until another thread completes its execution. If t is a Thread object whose thread is currently executing, then t.join() will make sure that t is terminated before the next instruction is executed by the program. 9 Thread 1 Thread 2 Main Thread Run Run Join Join Implement Runnable Interface Simple Example Note The method in the interface is run. By being runnable a class can be used to create a thread. 10 Here we instantiate Several PrintWord objects. Each one is used to create a thread. ArrayList threads = new ArrayList(); // Create a print word (which is runnable) PrintWord p = new PrintWord("First", 5); // Create a thread Thread t = new Thread(p); threads.add(t); // Create a print word (which is runnable) PrintWord p2 = new PrintWord("Second", 5); // Create a thread Thread t2 = new Thread(p2); threads.add(t2); // Create a print word (which is runnable) PrintWord p3 = new PrintWord("Third", 5); // Create a thread Thread t3 = new Thread(p3); threads.add(t3); Now we start the threads for( Thread thread : threads) { thread.run(); } If we need the thread to combine information when they are done – Join() will wait until the thread ends before continuing for( Thread thread : threads) { try { thread.join(); } catch (InterruptedException e) { e.printStackTrace(); }; } Example Output: Not the thread complete so quickly it does not have time to switch Exercise We will compare a single version and multi thread version of the following process:(We will create the arrays one at a time - think about why)    Create the arrays of the specified size Load each slot of the array with a random number (0 – 999)      In a separate step get the sum of all number in the array Exercise We will create two methods that do the previous process One Will be single Thread A second Will be Multiple Threads We will compare the time it takes each This will vary on different machines We will do this as a group Exercise Timings: long startTime = System.currentTimeMillis(); // Do work here (call method that does task) long endTime = System.currentTimeMillis(); System.out.println("Total execution time: " + (endTime - startTime) + "ms"); Lab Step 1 Create a Main class that and main method and the following variables: Create a class called Populate that implements runnable With the following: Lab Step 2 This is where the work starts We will create the single thread version first (in the main class) We need a method to create an array of a given size And add a numbers to each position (Random 0 -999) Another method will loop and create the specified number of array and return the sum of all of them combined We will do this as a team Lab Step 3 Repeat – but create multiple threads We will do this as a team Always10 Usually8 Often6 Generally4 Sometimes3 Seldom2 Rarely1 Never0 Java Concurrency Lab Extend Thread Java Concurrency Lab Extend Thread Presenter Name Agenda 9/3/20XX What is the Thread Class Extending the Thread Class Simple Example Presentation Title 2 Introduction A thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. Presentation Title 3 Introduction A single java process can have many threads. The main process can spawn thread, or a thread can spawn a new thread! Presentation Title 4 Introduction We can define a thread in the following two ways: By extending Thread class By implementing Runnable interface 5 Thread Thread (Class) Runnable (Interface) run() method Override Extends Implements When to extending the thread class In General, you would rarely need to do this. Extending the Thread class is reserved for creating new thread functionality. If I need to change how a thread does something which given the nature of this, it would be fraught with danger. Presentation Title 6 Thread Class Thread a line of execution within a program. Each program can have multiple associated threads. Each thread has a priority which is used by the thread scheduler to determine which thread must run first. Java provides a thread class that has various method calls in order to manage the behavior of threads by providing constructors and methods to perform operations on threads. Presentation Title 7 Thread.sleep() Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers. The thread does not lose ownership of any monitors.(Don’t worry about this yet) 8 join() The join() method which allows one thread to wait until another thread completes its execution. If t is a Thread object whose thread is currently executing, then t.join() will make sure that t is terminated before the next instruction is executed by the program. 9 Thread 1 Thread 2 Main Thread Run Run Join Join Extend the Thread Class Simple Example Note In the case of multithreading, we can't predict the exact order of output because it will vary from system to system or JVM to JVM. Presentation Title 10 This thread class will run a loop until it finds a number divisibly by the one passed into the constructor. It calls sleep for 50 milliseconds It keep track of home many random number it generates Example Outputs This main method creates three threads. It then call run which will spawn them. It calls join on each thread. This cause main to wait for the thread to finish This means its run method must complete – so it is finishes Then it prints and aggregates the results. Lab Step 1 Create a class that Extends thread Override the run method Have a loop that runs until it find 10 even numbers Random Generate a number 0 - 500 Keep track of the count of the even and odd number. Sleep for the number milliseconds based on the random number Lab Step 2 Create three instances of your thread class Store them in an ArrayList Run all three Join all three Get the counts of odds and evens Print the average for all threads Always10 Usually8 Often6 Generally4 Sometimes3 Seldom2 Rarely1 Never0