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
We’ve been working hard to make Obsidian Scheduler even better. Version 1.1 is now available. Features added in this release include Perfectly distributed load balancing across runnings hosts within seconds of pool membership changes Header icons indicating the number of active hosts Ability to disable targeted scheduler instances without shutting them down Ad hoc job … 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
This is the first part in a series that we’re going to be doing on Java concurrency. Specifically, we are going to dive into the concurrency tools built into Java 1.5 and beyond. We’re going to assume you have a basic understanding of synchronization and volatile keywords. The first post will cover semaphores - specifically counting semaphores. … Read more
Here at Carfey, we’ve used Java’s native scripting API in our upcoming job scheduler to allow our clients to deploy new scripts at any time they wish, without redeploying their applications. Combined with our advanced configuration support, we think we’ve found a killer combination of flexibility and power. The scripting API was outlined in JSR … Read more