In times past, when it came to tracking down sporadic memory problems in a complex Java application, it required using a commercial product such as JProbe or a lot of painful and inefficient attempts to recreate the issue. Even if the problem were easy to recreate, unless the problem was blatantly obvious, your application might … Read more
Object Relational Mapping tools like Hibernate have helped developers make huge productivity gains in dealing with relational databases in the past several years. ORMs free developers to focus on application logic and avoid writing a lot of boilerplate SQL for simple tasks like inserts or queries. However, the well-documented problems with object-relational impedance mismatch inevitably … Read more
While we’ve already written a post on our scripting support in Obsidian, this post will focus specifically on our Groovy support, what we use it for and what it makes possible for you. Given that Groovy is built for the JVM and almost any java code will work as is in a groovy script/class, supporting … Read more
Java 7 is finally nearing general release, but I have to say that I’m fairly unimpressed by the features being delivered considering Java 6 was released 4 1/2 years ago. It’s already been delayed for years, and what is there to show for it? The time between Java 6 and 7 is almost a third … Read more
Obsidian Scheduler provides enterprise scheduling features while natively supporting pooling and clustering, or in other words, load balancing and fault tolerance. But Obsidian does so in a way that is painless and non-invasive. In fact, you don’t have to do anything. Load balancing and fault tolerance are built into each instance of Obsidian Scheduler whether … Read more
Java has boasted various collections classes for many years now, all to deal with common programming problems. When we need synchronized collections, we used to just wrap our regular collections with a call to java.util.Collections.synchronizedList() or the other similar methods. Sometimes though, these methods don’t scale as they are a very primitive and unoptimized way … Read more
As discussed in Part 3, the thread pools introduced in Java 1.5 provided core support that was quickly a favourite of many java developers. Internally, the implementations make smart use of another concurrency feature introduced in java 1.5 – Blocking Queues. Queue First, a brief review of what a standard queue is. In computer science, … Read more
One of the beautiful things about Java from its very first release was the ease with which we could write multi-threaded programs and introduce asynchronous processing into our designs. The Thread class and Runnable interface combined with Java’s memory management model meant for straightforward thread programming. But as discussed in Part 3, neither the Thread … Read more
One of the most generally useful concurrency enhancements delivered in Java 1.5 was the introduction of customizable thread pools. These thread pools give you quite a bit of control over things such as number of threads, reuse of threads, scheduling and thread construction. Let’s review these. First, thread pools. Let’s dive right into java.util.concurrent.ExecutorService, which … Read more
Java’s synchronized keyword is a wonderful tool – it allows us a simple and reliable way to synchronize access to critical sections and it’s not too hard to understand. But sometimes we need more control over synchronization. Either we need to control types of access (read and write) separately, or it is cumbersome to use … Read more