Latest Articles

26 November 2015

This article covers lock waiting conditions in Java (java.util.concurrent.locks.Condition)

Locking conditions provide the ability for a given thread to wait for some arbitrary condition to happen while executing a critical section of code. In this context, a critical section is a section of... Read more

concurrency java

Read/Write Locks in Java (ReentrantReadWriteLock)

18 October 2015

This article covers Read/Write locks in Java (ReentrantReadWriteLock implementation)

Read/Write locks - also known as Shared/Exclusive locks - are designed for use cases where an application allows simultaneous read access to some piece of data by multiple processes at the same time, ... Read more

concurrency java

Locking in JPA (LockModeType)

30 August 2015

This article covers the optimistic and pessimistic locking mechanisms available in the Java Persistence API (using LockModeType)

Locking plays an important role in concurrent applications. The Java Persistence API provides distinct types of locking mechanisms that may be classified in a couple of major groups: pessimistic and o... Read more

concurrency java-ee jpa

JPA entity versioning (@Version and Optimistic Locking)

29 July 2015

This article covers database optimistic locking in general and also demonstrates how to implement optimistic locking in Java Persistence API (JPA) entities by using the @Version annotation

Optimistic locking is a mechanism that prevents an application from being affected by the "lost update" phenomenon in a concurrent environment while allowing some high degree of concurrency ... Read more

concurrency java-ee jpa

JPA OneToOne generates additional queries

26 June 2015

This article explains why do the Java Persistence API (JPA) often generates additional queries while dealing with OneToOne relationships

It's true that JPA may generate additional queries while dealing with OneToOne relationships, and this is a subject where users usually ask for help in online forums and Q&A websites. This article... Read more

java-ee jpa

Java EE EJB concurrency (ConcurrencyManagement, Lock and LockType)

31 May 2015

This article will cover EJB concurrent access configuration (both container and bean managed) resorting to Lock, LockType and ConcurrencyManagement primitives.

Even though Stateless EJB's may never be concurrently accessed by more than a single client call, this article would be otherwise incomplete if it did not mention this kind of EJB's. Stateless EJB's a... Read more

concurrency ejb java-ee

JPA EXTENDED Persistence Context

19 April 2015

In this article we will cover the differences between TRANSACTION and EXTENDED Persistence Context (Entity Manager).

A container managed Persistence Context is always associated with a specific scope among the following available scopes: TRANSACTION or EXTENDED. The more common scenario is the TRANSACTION scope, whi... Read more

ejb java-ee jpa

Asynchronous Servlets in Java

18 February 2015

In this article we will cover Asynchronous Servlets in Java. We will also implement a use case that demonstrates the concrete advantages of asynchronous processing with servlets.

An excessive number of threads running simultaneously in a Java application may consume a lot of resources. This is no exception for a web based Java application. Incoming requests are handled by dedi... Read more

async java-ee servlet web

About the author

Gonçalo Marques is a Software Engineer with several years of experience in software development and architecture definition. During this period his main focus was delivering software solutions in banking, telecommunications and governmental areas. He created the Bytes Lounge website with one ultimate goal: share his knowledge with the software development community. His main area of expertise is Java and open source.

GitHub profile: https://github.com/gonmarques

He is also the author of the WiFi File Browser Android application: