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What is behind System.nanoTime()?

In java world there is a very good perception about System.nanoTime(). There is always some guys who says that it is fast, reliable and, whenever possible, should be used for timings instead of System.currentTimemillis(). In overall he is absolutely lying, it is not bad at all, but there are some drawback which developer should be aware about. Also, although they ...

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Practical Garbage Collection, part 1 – Introduction

This is the first part of a series of blog posts I intend to write, whose aim will be to explain how garbage collection works in the real world (in particular, with the JVM). I will cover some theory that I believe is necessary to understand garbage collection enough for practical purposes, but will keep it to a minimum. The ...

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Debugging the JVM

In some (rare) cases you might find yourself in the situation that you managed to crash the JVM itself. I most recently managed this by setting the name of a ThreadGroup to null. In these cases it is useful to debug the JVM itself so that the crash can be located more precisely. Here are the steps to do it ...

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JVM options: -client vs -server

Have you ever wonder what is this -client or -server switch when you run your java app? e.g.: javaw.exe -client com.blogspot.sdoulger.LoopTest that are also displayed in the Help of the java.exe e.g. where options include: -client to select the “client” VM -server to select the “server” VM What’s the difference between the -client and -server systems? These two systems are ...

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