follow-on-locking problem

Author: Tigran Sargsyan

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java

@@ -1,38 +1,114 @@
 package org.hibernate.bugs;
 
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.EntityManagerFactory;
+import jakarta.persistence.LockModeType;
 import jakarta.persistence.Persistence;
+import jakarta.persistence.TypedQuery;
+import java.util.List;
+import java.util.concurrent.BrokenBarrierException;
+import java.util.concurrent.CyclicBarrier;
+import org.hibernate.bugs.entity.MainEntity;
+import org.hibernate.bugs.entity.RelatedEntity;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * This template demonstrates how to develop a test case for Hibernate ORM, using the Java Persistence API.
  */
 class JPAUnitTestCase {
 
-	private EntityManagerFactory entityManagerFactory;
-
-	@BeforeEach
-	void init() {
-		entityManagerFactory = Persistence.createEntityManagerFactory( "templatePU" );
-	}
-
-	@AfterEach
-	void destroy() {
-		entityManagerFactory.close();
-	}
-
-	// Entities are auto-discovered, so just add them anywhere on class-path
-	// Add your tests, using standard JUnit.
-	@Test
-	void hhh123Test() throws Exception {
-		EntityManager entityManager = entityManagerFactory.createEntityManager();
-		entityManager.getTransaction().begin();
-		// Do stuff...
-		entityManager.getTransaction().commit();
-		entityManager.close();
-	}
+    private EntityManagerFactory entityManagerFactory;
+
+    @BeforeEach
+    void init() {
+        entityManagerFactory = Persistence.createEntityManagerFactory("templatePU");
+    }
+
+    @AfterEach
+    void destroy() {
+        entityManagerFactory.close();
+    }
+
+    @Test
+    void hhh123Test() throws Exception {
+
+        long id = fillData();
+
+        var threadsCount = 50;
+        CyclicBarrier cyclicBarrier = new CyclicBarrier(threadsCount);
+
+        Thread[] threads = new Thread[threadsCount];
+        for (var i = 0; i < threadsCount; i++) {
+            var thread = new Thread(() -> {
+                EntityManager entityManager = entityManagerFactory.createEntityManager();
+                var transaction = entityManager.getTransaction();
+
+                try {
+                    cyclicBarrier.await();
+                } catch (InterruptedException | BrokenBarrierException e) {
+                    throw new RuntimeException(e);
+                }
+
+                transaction.begin();
+
+                TypedQuery<MainEntity> query = entityManager.createQuery(
+                    "SELECT m FROM MainEntity m INNER JOIN m.relatedEntity WHERE m.id = :id",
+                    MainEntity.class
+                );
+                query.setParameter("id", id);
+                // test passes, if followOnLocking is disabled
+                query.setHint("hibernate.query.followOnLocking", true);
+                query.setLockMode(LockModeType.PESSIMISTIC_WRITE);
+                var result = query.getSingleResult();
+
+                result.mainCounter++;
+                result.relatedEntity.get(0).relatedCounter++;
+                entityManager.merge(result);
+                entityManager.flush();
+
+                transaction.commit();
+                entityManager.close();
+            });
+
+            thread.start();
+            threads[i] = thread;
+        }
+
+        for (var thread : threads) {
+            thread.join();
+        }
+
+        EntityManager entityManager = entityManagerFactory.createEntityManager();
+        var transaction = entityManager.getTransaction();
+        transaction.begin();
+        var entity = entityManager.find(MainEntity.class, id);
+        assertEquals(threadsCount, entity.mainCounter);
+        assertEquals(threadsCount, entity.relatedEntity.get(0).relatedCounter);
+        entityManager.getTransaction().commit();
+        entityManager.close();
+    }
+
+    private long fillData() {
+        var entityManager = entityManagerFactory.createEntityManager();
+        var transaction = entityManager.getTransaction();
+        transaction.begin();
+        MainEntity mainEntity = new MainEntity();
+        RelatedEntity relatedEntity = new RelatedEntity();
+        relatedEntity.relatedCounter = 0;
+        relatedEntity.main = mainEntity;
+        mainEntity.mainCounter = 0;
+        mainEntity.relatedEntity = List.of(relatedEntity);
+
+        entityManager.persist(relatedEntity);
+        entityManager.persist(mainEntity);
+
+        transaction.commit();
+        entityManager.close();
+        return mainEntity.id;
+    }
+
 }

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/entity/MainEntity.java

@@ -0,0 +1,23 @@
+package org.hibernate.bugs.entity;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToMany;
+import java.util.List;
+
+@Entity
+
+public class MainEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    public long id;
+
+    @OneToMany(mappedBy = "main")
+    public List<RelatedEntity> relatedEntity;
+
+    public int mainCounter;
+
+}

orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/entity/RelatedEntity.java

@@ -0,0 +1,21 @@
+package org.hibernate.bugs.entity;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+
+@Entity
+public class RelatedEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    public long id;
+
+    @ManyToOne
+    public MainEntity main;
+
+    public int relatedCounter;
+
+}

orm/hibernate-orm-6/src/test/resources/META-INF/persistence.xml

@@ -18,7 +18,7 @@
             <property name="hibernate.connection.url" value="jdbc:h2:mem:db1;DB_CLOSE_DELAY=-1"/>
             <property name="hibernate.connection.username" value="sa"/>
 
-            <property name="hibernate.connection.pool_size" value="5"/>
+            <property name="hibernate.connection.pool_size" value="50"/>
 
             <property name="hibernate.show_sql" value="true"/>
             <property name="hibernate.format_sql" value="true"/>