AdvancedJavaLabs · github-classroom · Sep 30, 2025 · Sep 30, 2025 · Oct 7, 2025 · Oct 7, 2025
diff --git a/README.md b/README.md
@@ -1,3 +1,4 @@
+[![Review Assignment Due Date](https://classroom.github.com/assets/deadline-readme-button-22041afd0340ce965d47ae6ef1cefeee28c7c493a6346c4f15d667ab976d596c.svg)](https://classroom.github.com/a/AwTYhPar)
 # Лабораторная работа № 1: определение достижимости параллелизма и реализация параллельных алгоритмов.
 
 Шаги выполнения:

diff --git a/build.gradle.kts b/build.gradle.kts
@@ -1,5 +1,6 @@
 plugins {
     kotlin("jvm") version "1.9.20"
+    java
     application
 }
 
@@ -12,10 +13,14 @@ repositories {
 
 dependencies {
     testImplementation(kotlin("test"))
+    testImplementation("org.openjdk.jcstress:jcstress-core:0.16")
+    testAnnotationProcessor("org.openjdk.jcstress:jcstress-core:0.16")
 }
 
 tasks.test {
     useJUnitPlatform()
+    minHeapSize = "6G"
+    maxHeapSize = "10G"
 }
 
 kotlin {
@@ -24,4 +29,19 @@ kotlin {
 
 application {
     mainClass.set("MainKt")
-}
+}
+
+// JCStress runner task: runs JCStress tests located on the test runtime classpath
+// Use: ./gradlew jcstress [-PjcstressArgs="-v -m quick"]
+tasks.register<JavaExec>("jcstress") {
+    group = "verification"
+    description = "Run JCStress stress tests"
+    mainClass.set("org.openjdk.jcstress.Main")
+    classpath = sourceSets.test.get().runtimeClasspath
+    dependsOn("testClasses")
+
+    val argsProp = project.findProperty("jcstressArgs") as String?
+    if (!argsProp.isNullOrBlank()) {
+        args = argsProp.split("\\s+".toRegex())
+    }
+}
diff --git a/docs/performance_comparison_line.png b/docs/performance_comparison_line.png
diff --git a/docs/sync_error.png b/docs/sync_error.png
diff --git a/docs/thread1.txt b/docs/thread1.txt
@@ -0,0 +1,38 @@
+thread: 1
+
+Times for 10 vertices and 50 connections: 
+Serial: 1
+Parallel: 2
+--------
+Times for 100 vertices and 500 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 1000 vertices and 5000 connections: 
+Serial: 1
+Parallel: 0
+--------
+Times for 10000 vertices and 50000 connections: 
+Serial: 3
+Parallel: 3
+--------
+Times for 10000 vertices and 100000 connections: 
+Serial: 1
+Parallel: 3
+--------
+Times for 50000 vertices and 1000000 connections: 
+Serial: 12
+Parallel: 23
+--------
+Times for 100000 vertices and 1000000 connections: 
+Serial: 15
+Parallel: 27
+--------
+Times for 1000000 vertices and 10000000 connections: 
+Serial: 260
+Parallel: 385
+--------
+Times for 2000000 vertices and 10000000 connections: 
+Serial: 268
+Parallel: 341
+--------
diff --git a/docs/thread12.txt b/docs/thread12.txt
@@ -0,0 +1,38 @@
+thread: 12
+
+Times for 10 vertices and 50 connections: 
+Serial: 0
+Parallel: 2
+--------
+Times for 100 vertices and 500 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 1000 vertices and 5000 connections: 
+Serial: 1
+Parallel: 4
+--------
+Times for 10000 vertices and 50000 connections: 
+Serial: 3
+Parallel: 8
+--------
+Times for 10000 vertices and 100000 connections: 
+Serial: 2
+Parallel: 14
+--------
+Times for 50000 vertices and 1000000 connections: 
+Serial: 12
+Parallel: 5
+--------
+Times for 100000 vertices and 1000000 connections: 
+Serial: 15
+Parallel: 7
+--------
+Times for 1000000 vertices and 10000000 connections: 
+Serial: 177
+Parallel: 54
+--------
+Times for 2000000 vertices and 10000000 connections: 
+Serial: 368
+Parallel: 89
+--------
diff --git a/docs/thread2.txt b/docs/thread2.txt
@@ -0,0 +1,38 @@
+thread: 2
+
+Times for 10 vertices and 50 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 100 vertices and 500 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 1000 vertices and 5000 connections: 
+Serial: 1
+Parallel: 0
+--------
+Times for 10000 vertices and 50000 connections: 
+Serial: 3
+Parallel: 3
+--------
+Times for 10000 vertices and 100000 connections: 
+Serial: 2
+Parallel: 6
+--------
+Times for 50000 vertices and 1000000 connections: 
+Serial: 14
+Parallel: 24
+--------
+Times for 100000 vertices and 1000000 connections: 
+Serial: 16
+Parallel: 15
+--------
+Times for 1000000 vertices and 10000000 connections: 
+Serial: 271
+Parallel: 209
+--------
+Times for 2000000 vertices and 10000000 connections: 
+Serial: 314
+Parallel: 213
+--------
diff --git a/docs/thread4.txt b/docs/thread4.txt
@@ -0,0 +1,38 @@
+thread: 4
+
+Times for 10 vertices and 50 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 100 vertices and 500 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 1000 vertices and 5000 connections: 
+Serial: 1
+Parallel: 1
+--------
+Times for 10000 vertices and 50000 connections: 
+Serial: 3
+Parallel: 3
+--------
+Times for 10000 vertices and 100000 connections: 
+Serial: 2
+Parallel: 5
+--------
+Times for 50000 vertices and 1000000 connections: 
+Serial: 13
+Parallel: 22
+--------
+Times for 100000 vertices and 1000000 connections: 
+Serial: 16
+Parallel: 16
+--------
+Times for 1000000 vertices and 10000000 connections: 
+Serial: 257
+Parallel: 104
+--------
+Times for 2000000 vertices and 10000000 connections: 
+Serial: 373
+Parallel: 147
+--------
diff --git a/docs/thread8.txt b/docs/thread8.txt
@@ -0,0 +1,38 @@
+thread: 8
+
+Times for 10 vertices and 50 connections: 
+Serial: 0
+Parallel: 2
+--------
+Times for 100 vertices and 500 connections: 
+Serial: 0
+Parallel: 1
+--------
+Times for 1000 vertices and 5000 connections: 
+Serial: 0
+Parallel: 2
+--------
+Times for 10000 vertices and 50000 connections: 
+Serial: 3
+Parallel: 7
+--------
+Times for 10000 vertices and 100000 connections: 
+Serial: 2
+Parallel: 14
+--------
+Times for 50000 vertices and 1000000 connections: 
+Serial: 12
+Parallel: 4
+--------
+Times for 100000 vertices and 1000000 connections: 
+Serial: 17
+Parallel: 7
+--------
+Times for 1000000 vertices and 10000000 connections: 
+Serial: 285
+Parallel: 75
+--------
+Times for 2000000 vertices and 10000000 connections: 
+Serial: 390
+Parallel: 103
+--------
diff --git a/docs/thread_comparison_line.png b/docs/thread_comparison_line.png
diff --git a/src/main/java/org/itmo/Graph.java b/src/main/java/org/itmo/Graph.java
@@ -1,9 +1,11 @@
 package org.itmo;
 
 import java.util.*;
-import java.util.concurrent.*;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicIntegerArray;
 
 class Graph {
     private final int V;
@@ -24,6 +26,80 @@ void addEdge(int src, int dest) {
     }
 
     void parallelBFS(int startVertex) {
+        AtomicIntegerArray visited = new AtomicIntegerArray(V);
+
+        List<Integer> currentFrontier = new ArrayList<>();
+        currentFrontier.add(startVertex);
+        visited.set(startVertex, 1);
+
+        int numThreads = Runtime.getRuntime().availableProcessors();
+        ExecutorService executor = Executors.newFixedThreadPool(numThreads);
+
+        try {
+            while (!currentFrontier.isEmpty()) {
+                final List<Integer> frontier = currentFrontier;
+                final int frontierSize = frontier.size();
+
+                List<List<Integer>> threadLocalBuffers = new ArrayList<>(numThreads);
+                for (int t = 0; t < numThreads; t++) {
+                    threadLocalBuffers.add(new ArrayList<>());
+                }
+
+                int chunkSize = Math.max(1, (frontierSize + numThreads - 1) / numThreads);
+                CountDownLatch latch = new CountDownLatch(numThreads);
+
+                for (int threadId = 0; threadId < numThreads; threadId++) {
+                    final int start = threadId * chunkSize;
+                    final int end = Math.min(start + chunkSize, frontierSize);
+                    final List<Integer> localBuffer = threadLocalBuffers.get(threadId);
+
+                    if (start >= frontierSize) {
+                        latch.countDown();
+                        continue;
+                    }
+
+                    executor.execute(() -> {
+                        try {
+                            for (int i = start; i < end; i++) {
+                                int vertex = frontier.get(i);
+
+                                for (int neighbor : adjList[vertex]) {
+                                    if (visited.compareAndSet(neighbor, 0, 1)) {
+                                        localBuffer.add(neighbor);
+                                    }
+                                }
+                            }
+                        } finally {
+                            latch.countDown();
+                        }
+                    });
+                }
+
+                try {
+                    latch.await();
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    throw new RuntimeException("BFS interrupted", e);
+                }
+
+                List<Integer> nextFrontier = new ArrayList<>();
+                for (List<Integer> buffer : threadLocalBuffers) {
+                    nextFrontier.addAll(buffer);
+                }
+
+                currentFrontier = nextFrontier;
+            }
+        } finally {
+            executor.shutdown();
+            try {
+                if (!executor.awaitTermination(60, TimeUnit.SECONDS)) {
+                    executor.shutdownNow();
+                }
+            } catch (InterruptedException e) {
+                executor.shutdownNow();
+                Thread.currentThread().interrupt();
+            }
+        }
     }
 
     //Generated by ChatGPT

diff --git a/src/main/java/org/itmo/UnsafeCounter.java b/src/main/java/org/itmo/UnsafeCounter.java
@@ -0,0 +1,13 @@
+package org.itmo;
+
+public class UnsafeCounter {
+    private int counter = 0;
+
+    public void increment() {
+        counter++; // <-- гонка данных
+    }
+
+    public int get() {
+        return counter;
+    }
+}