advanced #1

Merged
HoseinA05 merged 1 commits from develop into master 2026-07-30 17:22:11 +00:00
4 changed files with 55 additions and 31 deletions
@@ -20,17 +20,18 @@ public class DeadlockPreventionWorkshop {
}
public static void useResources(Resource r1, Resource r2) {
// TODO: Prevent deadlock by enforcing a consistent lock acquisition order
// Hint: Compare resource IDs and always synchronize on the resource with the smaller ID first.
System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r1.getName());
synchronized (r1) {
System.out.println("+ " + Thread.currentThread().getName() + " locked " + r1.getName());
Resource first = (r1.getId() < r2.getId()) ? r1 : r2;
Resource second = (r1.getId() < r2.getId()) ? r2 : r1;
System.out.println(Thread.currentThread().getName() + " is attempting to lock " + first.getName());
synchronized (first) {
System.out.println("+ " + Thread.currentThread().getName() + " locked " + first.getName());
try { Thread.sleep(100); } catch (InterruptedException ignored) {}
System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r2.getName());
synchronized (r2) {
System.out.println("+ " + Thread.currentThread().getName() + " locked " + r2.getName());
System.out.println(Thread.currentThread().getName() + " is attempting to lock " + second.getName());
synchronized (second) {
System.out.println("+ " + Thread.currentThread().getName() + " locked " + second.getName());
System.out.println(Thread.currentThread().getName() + " using " + r1.getName() + " and " + r2.getName());
}
}
@@ -40,7 +41,7 @@ public class DeadlockPreventionWorkshop {
Resource resA = new Resource(1, "ResourceA");
Resource resB = new Resource(2, "ResourceB");
// Thread 1 locks A then B; Thread 2 locks B then A (causing deadlock if unordered)
Thread t1 = new Thread(() -> useResources(resA, resB), "Thread-1");
Thread t2 = new Thread(() -> useResources(resB, resA), "Thread-2");
@@ -5,16 +5,21 @@ import java.util.concurrent.locks.ReentrantLock;
public class LockWorkshop {
public static int counter = 0;
// TODO: Create a ReentrantLock instance to protect the critical section
private static final Lock lock = new ReentrantLock();
public static class MyRunnable implements Runnable {
@Override
public void run() {
int i;
for (i = 0; i < 1_000_000; i++) {
// TODO: Acquire the lock, increment the counter, and release the lock safely in a finally block
counter += 1;
lock.lock();
try {
counter += 1;
} finally {
lock.unlock();
}
}
System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i);
}
@@ -25,13 +30,13 @@ public class LockWorkshop {
Thread thread1 = new Thread(new MyRunnable(), "Thread-1");
Thread thread2 = new Thread(new MyRunnable(), "Thread-2");
thread1.start();
thread2.start();
thread1.join();
thread2.join();
System.out.println("Final counter value (expected 2000000): " + counter);
}
}
@@ -2,16 +2,18 @@ package workshop.exercises;
public class SynchronizedWorkshop {
public static int counter = 0;
// TODO: Define a lock object to prevent race condition
private static final Object lock = new Object();
public static class MyRunnable implements Runnable {
@Override
public void run() {
int i;
for (i = 0; i < 1_000_000; i++) {
// TODO: Use a synchronized block to protect the counter increment
counter += 1;
synchronized (lock) {
counter += 1;
}
}
System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i);
}
@@ -22,13 +24,13 @@ public class SynchronizedWorkshop {
Thread thread1 = new Thread(new MyRunnable(), "Thread-1");
Thread thread2 = new Thread(new MyRunnable(), "Thread-2");
thread1.start();
thread2.start();
thread1.join();
thread2.join();
System.out.println("Final counter value (expected 2000000): " + counter);
}
}
@@ -8,7 +8,7 @@ import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class TaylorSeries {
public static class CalculateSin implements Runnable {
private final MathContext mc = new MathContext(1000);
private final BigDecimal x;
@@ -21,14 +21,32 @@ public class TaylorSeries {
@Override
public void run() {
// TODO: Calculate the n-th term of the Taylor series for sin(x):
// Calculate the n-th term of the Taylor series for sin(x):
// term = (-1)^n * (x^(2n+1)) / (2n+1)!
// Add the term to the global sum ensuring thread-safety.
int exponent = 2 * n + 1;
BigDecimal numerator = x.pow(exponent, mc);
if (n % 2 == 1) {
numerator = numerator.negate();
}
BigDecimal denominator = factorial(exponent);
BigDecimal term = numerator.divide(denominator, mc);
// Add the term to the global sum, ensuring thread-safety by
// synchronizing on the shared class object that guards `sum`.
synchronized (TaylorSeries.class) {
sum = sum.add(term, mc);
}
}
// TODO: Implement factorial(k) using BigDecimal
private BigDecimal factorial(int k) {
return BigDecimal.ZERO;
BigDecimal result = BigDecimal.ONE;
for (int i = 2; i <= k; i++) {
result = result.multiply(BigDecimal.valueOf(i));
}
return result;
}
}
@@ -39,9 +57,8 @@ public class TaylorSeries {
sum = BigDecimal.ZERO;
BigDecimal x = new BigDecimal("0.01");
// Submit tasks to calculate terms
for (int i = 0; i < 100; i++) {
// TODO: Submit task to the thread pool
threadPool.submit(new CalculateSin(x, i));
}
threadPool.shutdown();
@@ -51,7 +68,6 @@ public class TaylorSeries {
Thread.currentThread().interrupt();
}
// Pre-calculated accurate value of sin(0.01) up to 1000 decimal places
BigDecimal accurateValue = new BigDecimal("0.009999833334166664682542438269099729038964385360169151033879" +
"1124794097345090639159659426367929614989901525182568937606738071143914781018343679925045223748779233" +
"4633395662957704288475175228160558357110105077439518716860615533070998720636987509269668842490541364" +