From 51c5f629ed01ac403f99e3f3cb76fdc842ba886c Mon Sep 17 00:00:00 2001 From: ZahraSadatMirvakili Date: Sun, 31 May 2026 23:12:30 +0330 Subject: [PATCH] multi --- pom.xml | 4 +-- .../exercises/DeadlockPreventionWorkshop.java | 17 ++++++----- .../java/workshop/exercises/LockWorkshop.java | 11 +++++-- .../exercises/SynchronizedWorkshop.java | 7 +++-- .../java/workshop/exercises/TaylorSeries.java | 29 ++++++++++++++----- 5 files changed, 45 insertions(+), 23 deletions(-) diff --git a/pom.xml b/pom.xml index ca0cc46..9a7758d 100644 --- a/pom.xml +++ b/pom.xml @@ -17,13 +17,13 @@ org.junit.jupiter junit-jupiter-api - 5.10.0 + 5.10.2 test org.junit.jupiter junit-jupiter-engine - 5.10.0 + 5.9.3 test diff --git a/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java b/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java index 91ba6a8..8073092 100644 --- a/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java +++ b/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java @@ -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. + + 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 " + r1.getName()); - synchronized (r1) { - System.out.println("+ " + Thread.currentThread().getName() + " locked " + r1.getName()); + 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()); } } diff --git a/src/main/java/workshop/exercises/LockWorkshop.java b/src/main/java/workshop/exercises/LockWorkshop.java index ec24ecf..42ca9ad 100644 --- a/src/main/java/workshop/exercises/LockWorkshop.java +++ b/src/main/java/workshop/exercises/LockWorkshop.java @@ -6,15 +6,20 @@ 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); } diff --git a/src/main/java/workshop/exercises/SynchronizedWorkshop.java b/src/main/java/workshop/exercises/SynchronizedWorkshop.java index 9259d8e..0ea1648 100644 --- a/src/main/java/workshop/exercises/SynchronizedWorkshop.java +++ b/src/main/java/workshop/exercises/SynchronizedWorkshop.java @@ -3,15 +3,16 @@ package workshop.exercises; public class SynchronizedWorkshop { public static int counter = 0; - // TODO: Define a lock object to prevent race condition + public 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); } diff --git a/src/main/java/workshop/exercises/TaylorSeries.java b/src/main/java/workshop/exercises/TaylorSeries.java index d63a18e..7118eb2 100644 --- a/src/main/java/workshop/exercises/TaylorSeries.java +++ b/src/main/java/workshop/exercises/TaylorSeries.java @@ -19,29 +19,44 @@ public class TaylorSeries { this.n = n; } + private static void accumulate(BigDecimal term){ + synchronized (sumLock){ + sum = sum.add(term); + } + } + @Override public void run() { - // TODO: 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 termNumerator = x.pow(exponent, mc); + BigDecimal termDenominator = factorial(exponent); + BigDecimal termValue = termNumerator.divide(termDenominator); + + if (n % 2 != 0){ + termValue = termValue.negate(); + } } - // TODO: Implement factorial(k) using BigDecimal private BigDecimal factorial(int k) { - return BigDecimal.ZERO; + BigDecimal reault = BigDecimal.ONE; + for (int i = 0; i <= k ; i++) { + reault = reault.multiply(BigDecimal.valueOf(i), mc); + } + return reault; } } public static BigDecimal sum = BigDecimal.ZERO; + private static final Object sumLock = new Object(); public static void main(String[] args) { ExecutorService threadPool = Executors.newFixedThreadPool(4); 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.execute(new CalculateSin(x, i)); } threadPool.shutdown();