Deadlock

Author: AnghelLeonard

HibernateSpringBootDeadlockExample/src/main/java/com/bookstore/repository/AuthorRepository.java

@@ -1,16 +1,23 @@
 package com.bookstore.repository;
 
 import com.bookstore.entity.Author;
+import java.util.List;
 import java.util.Optional;
 import javax.persistence.LockModeType;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 @Repository
 public interface AuthorRepository extends JpaRepository<Author, Long> {
 
     @Override
     @Lock(LockModeType.PESSIMISTIC_WRITE)
-    public Optional<Author> findById(Long id);
+    public Optional<Author> findById(Long id);    
+    
+    @Modifying
+    @Query("UPDATE Author SET genre = ?1 WHERE id = ?2")
+    public void updateGenre(String genre, long id);        
 }

HibernateSpringBootDeadlockExample/src/main/java/com/bookstore/repository/BookRepository.java

@@ -5,12 +5,18 @@
 import javax.persistence.LockModeType;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 @Repository
 public interface BookRepository extends JpaRepository<Book, Long> {
 
     @Override
     @Lock(LockModeType.PESSIMISTIC_WRITE)
-    public Optional<Book> findById(Long id);        
+    public Optional<Book> findById(Long id);    
+    
+    @Modifying
+    @Query("UPDATE Book SET title = ?1 WHERE id = ?2")
+    public void updateTitle(String title, long id);        
 }

HibernateSpringBootDeadlockExample/src/main/java/com/bookstore/service/BookstoreService.java

@@ -40,8 +40,8 @@ protected void doInTransactionWithoutResult(
 
                     log.info("Starting first transaction (A) ...");
 
-                    Author author = authorRepository.findById(1L).orElseThrow();
-                    author.setGenre("Comedy"); // this ends successfully                    
+                    authorRepository.findById(1L).orElseThrow(); // get the lock
+                    authorRepository.updateGenre("Comedy", 1L);
 
                     try {
                         log.info("Holding in place first transaction (A) for 10s ...");
@@ -51,8 +51,8 @@ protected void doInTransactionWithoutResult(
                         Thread.currentThread().interrupt();
                     }
 
-                    Book book = bookRepository.findById(1L).orElseThrow();
-                    book.setTitle("A happy day"); // this cannot be done, transaction (B) holds the lock                    
+                    bookRepository.findById(1L).orElseThrow(); // this cannot be done, transaction (B) holds the lock                    
+                    bookRepository.updateTitle("A happy day", 1L); 
                 }
             });
 
@@ -71,8 +71,8 @@ protected void doInTransactionWithoutResult(
 
                     log.info("Starting second transaction (B) ...");
 
-                    Book book = bookRepository.findById(1L).orElseThrow();
-                    book.setTitle("A long night"); // this ends successfully                                       
+                    bookRepository.findById(1L).orElseThrow(); // get the lock
+                    bookRepository.updateTitle("A long night", 1L);        
 
                     try {
                         log.info("Holding in place second transaction (B) for 10s ...");
@@ -82,8 +82,8 @@ protected void doInTransactionWithoutResult(
                         Thread.currentThread().interrupt();
                     }
 
-                    Author author = authorRepository.findById(1L).orElseThrow();
-                    author.setGenre("Horror"); // // this cannot be done, transaction (A) holds the lock                                    
+                    authorRepository.findById(1L).orElseThrow(); // this cannot be done, transaction (A) holds the lock
+                    authorRepository.updateGenre("Horror", 1L); 
                 }
             });