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8bb261ba35 |
@@ -20,18 +20,19 @@ public class DeadlockPreventionWorkshop {
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}
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public static void useResources(Resource r1, Resource r2) {
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// TODO: Prevent deadlock by enforcing a consistent lock acquisition order
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// Hint: Compare resource IDs and always synchronize on the resource with the smaller ID first.
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System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r1.getName());
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synchronized (r1) {
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System.out.println("+ " + Thread.currentThread().getName() + " locked " + r1.getName());
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Resource first = r1.getId() < r2.getId() ? r1 : r2;
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Resource second = r1.getId() < r2.getId() ? r2 : r1;
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System.out.println(Thread.currentThread().getName() + " is attempting to lock " + first.getName());
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synchronized (first) {
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System.out.println("+ " + Thread.currentThread().getName() + " locked " + first.getName());
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try { Thread.sleep(100); } catch (InterruptedException ignored) {}
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System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r2.getName());
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synchronized (r2) {
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System.out.println("+ " + Thread.currentThread().getName() + " locked " + r2.getName());
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System.out.println(Thread.currentThread().getName() + " using " + r1.getName() + " and " + r2.getName());
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System.out.println(Thread.currentThread().getName() + " is attempting to lock " + second.getName());
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synchronized (second) {
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System.out.println("+ " + Thread.currentThread().getName() + " locked " + second.getName());
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System.out.println(Thread.currentThread().getName() + " using " + first.getName() + " and " + second.getName());
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}
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}
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}
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@@ -6,15 +6,20 @@ import java.util.concurrent.locks.ReentrantLock;
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public class LockWorkshop {
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public static int counter = 0;
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// TODO: Create a ReentrantLock instance to protect the critical section
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private static Lock myLock = new ReentrantLock();
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public static class MyRunnable implements Runnable {
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@Override
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public void run() {
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int i;
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for (i = 0; i < 1_000_000; i++) {
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// TODO: Acquire the lock, increment the counter, and release the lock safely in a finally block
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myLock.lock();
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try{
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counter += 1;
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}finally {
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myLock.unlock();
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}
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}
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System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i);
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}
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@@ -1,18 +1,23 @@
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package workshop.exercises;
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import static java.lang.Thread.sleep;
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public class SynchronizedWorkshop {
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public static int counter = 0;
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// TODO: Define a lock object to prevent race condition
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private static Object lock = new Object();
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public static class MyRunnable implements Runnable {
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@Override
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public void run() {
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int i;
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for (i = 0; i < 1_000_000; i++) {
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// TODO: Use a synchronized block to protect the counter increment
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counter += 1;
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synchronized (lock){
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counter++;
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}
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}
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System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i);
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}
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}
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@@ -19,28 +19,44 @@ public class TaylorSeries {
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this.n = n;
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}
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@Override
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public void run() {
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// TODO: Calculate the n-th term of the Taylor series for sin(x):
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// term = (-1)^n * (x^(2n+1)) / (2n+1)!
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// Add the term to the global sum ensuring thread-safety.
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BigDecimal numarator = x.pow((2*n)+1 , mc);
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BigDecimal demenator = factorial(2*n+1);
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BigDecimal totalvalue = numarator.divide(demenator , mc);
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if(n%2 == 1){
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totalvalue = totalvalue.negate();
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}
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synchronized (sumlock){
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sum = sum.add(totalvalue);
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}
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}
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// TODO: Implement factorial(k) using BigDecimal
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private BigDecimal factorial(int k) {
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return BigDecimal.ZERO;
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BigDecimal result = BigDecimal.ONE;
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for(int i = 1 ; i <= k ; i++){
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result = result.multiply(BigDecimal.valueOf(i) , mc);
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}
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return result;
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}
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}
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public static BigDecimal sum = BigDecimal.ZERO;
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private static Object sumlock = new Object();
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public static void main(String[] args) {
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ExecutorService threadPool = Executors.newFixedThreadPool(4);
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sum = BigDecimal.ZERO;
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BigDecimal x = new BigDecimal("0.01");
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// Submit tasks to calculate terms
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for (int i = 0; i < 100; i++) {
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threadPool.execute(new CalculateSin(x , i));
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// TODO: Submit task to the thread pool
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}
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