Articles

The Cost Of Consistency: When 9ms Is 1s Too Much

The CAP theorem remains one of the most important tools in my software developer's toolbelt. Used correctly, it can help create services and products that can offer an excellent user experience and protect revenue during partial failures. Used incorrectly, it can lead to a poor user experience and loss ... read more

Pessimistic Optimism: The Case Of Unexpected Deadlocks

Despite the fact I've been developing software in one way or another for almost 20 years, I'm constantly surprised how things work, and, once the frustration wears off, I'm intrigued when things break. Lucky for me, over the last few weeks, I've been surprised, frustrated, and ... read more

The Concurrency Of ConcurrentHashMap

Java's ConcurrentHashMap is an excellent point of study when learning about Java's Memory Model. It employs numerous techniques to provide lock-free reads while still guaranteeing safe publication of objects. This article represents my attempt to take the magic out of the ConcurrentHashMap implementation. ... read more

Impact Of Local Variable Declaration Location

Does the location of a local variable's declaration result in performance changes of a method? For example, will a String variable, s, declared outside of a loop exhibit "better" performance than when declared inside a loop? In Java, looking at a class' bytecode explains, irrefutably, why the answer is ... read more

Safe Publication Of Transient Members

A very common (and quite dangerous) tripping point I find in concurrent Java code is that of unsafe member publication of otherwise safely-published objects. Of course, concurrent code is difficult to get right and I occasionally find myself identifying the same mistake in my own code---but usually only after a ... read more

Redirecting "derby.log" To An SLF4J Logger

More and more, I find myself using Apache Derby as an embedded database for personal projects. One inconvenience, however, is the persistent derby.log file than inevitably gets created at startup. It can, of course, be disabled entirely, but I'd like Derby errors to be put into my application ... read more

Tracing Servlet Requests

Tracing through Servlet-based web application log files isn't always as convenient as one may hope. Sure, when using Tomcat, we may rely on the thread names (such as http-8080-2), but sometimes they seem to bleed into each other resulting in a difficult structure to grep. Compounding this, an observer ... read more
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