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Adding Descriptors to MBeans in Mustang
Descriptors allow you to give additional information about MBeans to management clients. For example, a Descriptor on an MBean attribute might say what units it is measured in, or what its minimum and maximum possible values are. As of Mustang (Java SE 6), Descriptors are a basic part of the JMX API and are available in all types of MBeans. Here's the easiest way to use them. —
Eamonn McManus
Twice the IDE
Using Eclipse for the code, NetBeans for profiling, how cool is that? Well, it is, especially when you have a dual screen setup. I know a lot of developers do have such a setup today. Mine is a bit weird though... —
Romain Guy
CVSspam: Very Cool CVS Notification Tool
Code-reviews get a lot more automatic with this cool CVS notification tool. —
Tom Ball
Forums |
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Re: Pass by reference - why not?
Pass by reference is a valid programming model. That said it is not the Java programming model. To switch the Java programming model to pass by reference would break many things. Pass by reference is not safe and precludes one from making many of the assumptions that result in many of the speedups that we see from hotspot. Pass by reference may even break current GC. So this is not a matter of let the programmer decide.... —
Re: String.compareTo(String anotherString)
As far as I can figure out Hotspot doesn't really use the Java version of compareTo(), it uses hand-optimized assembly. Even with all that, yes, the "==" comparison speeds up identical string comparisons. The trouble is it slows down every other string comparison, since the "==" check is executed for every string comparison. So the question becomes: in real programs (not artificial microbenchmarks), what percentage of String.compareTo calls really compare the exact same objects? A small percentage makes the extra check hurt more than help. —
Also in Java Today |
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Synchronization optimizations in Mustang
"Uncontended locking performance has improved with nearly every JVM version. Mustang continues this trend by improving both the raw performance of uncontended and contended locking and introducing optimizations that can eliminate many lock operations." In Synchronization optimizations in Mustang, Brian Goetz looks at the two primary locking scenarios: locks that are heavily contended, and those that face little or no contention. "The JVM has separate code paths for contended ("slow path") and uncontended ("fast path") lock acquisition. A lot of effort has already gone into optimizing the fast path; Mustang further improves both the fast path and the slow path and adds a number of optimizations that can eliminate some locking entirely."
What Is Ruby on Rails
Ruby on Rails is emerging as a challenger to Java's dominance in building web applications -- the recently-released Beyond Java devotes two entire chapters to RoR, which it presents as a compelling combination for developing the kinds of web applications that have, at least until now, been the bread-and-butter of Java development. In the ONLamp article What Is Ruby on Rails, Curt Hibbs looks at the ideas behind RoR and how they contribute to high productivity and reduced development time.
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