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AOT and JVM
There have been a few AOT compilers for Java for some time. Two of the better known examples are GCJ and Excelsior JET. Even though Excelsior JET also has a JIT, the main focus was on the AOT aspect....
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Local variables scope in HotSpot
Assume the following code: public void foo() { C c = new C(); bar(c.baz); // assume that baz does not reference c } I was under the impression that HotSpot would not garbage collect c before the local...
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32-bit or 64-bit JVM? How about a Hybrid?
Before x86-64 came along, the decision on whether to use 32-bit or 64-bit mode for architectures that supported both was relatively simple: use 64-bit mode if the application requires the larger...
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JDK6u12, Java 7 and Devoxx
With JavaFX 1.0 out of the way, it seems like the Java 7 train has started moving again. Concurrency plans posted by Doug Lea. Two points of interest are that the parallel collections API is probably...
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Objects with no allocation overhead
We have all heard about how HotSpot is really good at dealing with short-lived objects (both allocation and GC), but the truth is that object allocation is still pretty costly when compared to...
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Load unsigned and better Compressed Oops
The HotSpot engineers are constantly working on improving performance. I noticed two interesting commits recently: Vladimir Kozlov improved Compressed Oops so that it doesn’t need to do...
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New JVM options and Scala iteration performance
Internal iterators like foreach tend to do very well in micro-benchmarks on the JVM. In fact, they often do as well as the equivalent manual while or for loop. There is a catch, however, and it’s easy...
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Performance of FastMath from Commons Math
Commons Math includes (in trunk and MATH_2_X branch) a FastMath class that is described as a “Faster, more accurate, portable alternative to StrictMath” and is implemented fully in Java (unlike...
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