Home » Tag Archives: JVM (page 10)

Tag Archives: JVM

Analysing a Java Core Dump

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In this post, I will show you how you can debug a Java core file to see what caused your JVM to crash. I will be using a core file I generated in my previous post: Generating a Java Core Dump. There are different ways you can diagnose a JVM crash, listed below: The hs_err_pid log file When a fatal ...

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How aggressive is method inlining in JVM?

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Ctrl + Alt + M is used in IntelliJ IDEA to extract method. Ctrl + Alt + M. It’s as simple as selecting a piece of code and hitting this combination. Eclipse also has it. I hate long methods. To the point where this smells way too long for me:                 public void ...

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Java 8: From PermGen to Metaspace

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As you may be aware, the JDK 8 Early Access is now available for download. This allows Java developers to experiment with some of the new language and runtime features of Java 8. One of these features is the complete removal of the Permanent Generation (PermGen) space which has been announced by Oracle since the release of JDK 7. Interned ...

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QOTD: Java Thread vs. Java Heap Space

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The following question is quite common and is related to OutOfMemoryError: unable to create new native thread problems during the JVM thread creation process and the JVM thread capacity. This is also a typical interview question I ask to new technical candidates (senior role). I recommend that you attempt to provide your own response before looking at the answer.   ...

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Java heap space, native heap and memory problems

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Recently, I was discussing with a friend, why the Java process uses more memory than the maximum heap that we set when starting the java process. All java objects that code creates are created inside Java heap space, which its size is defined by the -Xmx option. But a java process is consisted by many spaces, not only by the ...

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Java Thread: retained memory analysis

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This article will provide you with a tutorial allowing you to determine how much and where Java heap space is retained from your active application Java threads. A true case study from an Oracle Weblogic 10.0 production environment will be presented in order for you to better understand the analysis process. We will also attempt to demonstrate that excessive garbage ...

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Under the JVM hood – Classloaders

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Classloaders are a low level and often ignored aspect of the Java language among many developers. At ZeroTurnaround , our developers have had to live, breathe, eat, drink and almost get intimate with classloaders to produce the JRebel technology which interacts at a classloader level to provide live runtime class reloading, avoiding lengthy rebuilds/repackaging/redeploying cycles. Here are some of the ...

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Should I use a 32- or a 64-bit JVM?

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This is a question I have faced several times during my career in enterprise software development. Every once in awhile I’ve had to hand out recommendations for configuring a specific new environment. And more often than not, part of the question at hand was related to “Should I use a 32- or a 64-bit JVM”. To be honest, in the ...

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Escaping the JVM heap for memory intensive applications

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If you’ve ever allocated large Java heaps, you know that at some point – typically starting at around 4 GiB – you will start having issues with your garbage collection pauses. I won’t go into detail about why pauses happen in the JVM, but in short it happens when the JVM does full collections and you have a large heap. ...

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