Home » Author Archives: Dustin Marx (page 3)

Author Archives: Dustin Marx

jcmd: One JDK Command-Line Tool to Rule Them All

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I have referenced the handy JDK tool jcmd in several posts in the past, but focus exclusively on its usefulness here like I have previously done for jps. The jcmd tool was introduced with Oracle’s Java 7 and is particularly useful in troubleshooting issues with JVM applications by using it to identify Java processes’ IDs (akin to jps), acquiring heap ...

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Default HotSpot Maximum Direct Memory Size

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In my previous blog post Improved Documentation of HotSpot Options in Java 8, I wrote about the misunderstandings surrounding the HotSpot JVM‘s default setting for non-standard option -XX:MaxDirectMemorySize. In this post, I look at a simple way to determine the “default” maximum direct memory size in the HotSpot JVM. The Java 8 documentation for the Java launcher states the following ...

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Simplicity and Value of HotSpot’s -XshowSettings Flag

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A handy HotSpot JVM flag (option for the Java launcher java) is the -XshowSettings option. This option is described in the Oracle Java launcher description page as follows:                 -XshowSettings:category Shows settings and continues. Possible category arguments for this option include the following: all Shows all categories of settings. This is the default ...

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Improved Documentation of HotSpot Options in Java 8

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One of the small but welcome features introduced with Oracle’s HotSpot implementation of Java 8 is the addition of many common HotSpot Java launcher (java) options/flags to the launcher’s documentation. In the past, a developer interested in even some fairly common HotSpot JVM options has had to potentially look in multiple different sources to find “official” documentation on these flags. ...

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Leaner Java Collections with FastUtil

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In response to my recent post Discovering a Trove of Java Primitives Collection Handling on the GNU Trove library, TheAlchemist pointed out some advantages of fastutil over trove: “I much prefer fastutil (http://fastutil.di.unimi.it/), because it’s still in active development, has more features, supports large sizes (> 2^32), and has better documentation.” Attila-Mihaly Balazs has seconded this: “I second @TheAlchemist’s recommendation ...

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Significant Software Development Developments of 2015

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This post is my personal and opinionated assessment of some of the most significant developers related to software development in 2015. My previous years’ assessment are available for 2014, 2013, 2012, 2011, 2010, 2009, 2008, and 2007. As with these previous years’ assessments, this assessment of 2015’s major developments in software development are obviously biased, opinionated, and limited to my ...

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Discovering a Trove of Java Primitives Collection Handling

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While reading the blog post 5 Tips for Reducing Your Java Garbage Collection Overhead, I was reminded of the existence of a small Java collection library called Trove that “provides high speed regular and primitive collections for Java.” I am especially interested in the ability to apply Trove to allow for collections of primitives rather than requiring elements in collections ...

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Does PostgreSQL Have an ORA-01795-like Limit?

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The Oracle database requires that no more than 1000 entries be used in a SQL IN portion of a WHERE clause and will throw an ORA-01795 error if that number is exceeded. If a value needs to be compared to more than 1000 values, approaches other than use of IN must be applied. I wondered if this limitation applies to ...

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What Might a New @Deprecated Look Like?

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JDK Enhancement Proposal (JEP) 277 (“Enhanced Deprecation“) proposes to “revamp the deprecation annotation and provide tools to strengthen the tail end of the feature life cycle.” Some of the limitations of the current @java.lang.Deprecated have bothered me for some time. I particularly would like to be able to provide text with @Deprecated rather than being forced to place explanatory text ...

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Applying IDE Inspections to Custom Java Annotations

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The introduction of annotations with J2SE 5 has changed how we write and process Java. Besides Java SE’s predefined annotations, frameworks, IDEs, and toolkits have introduced their own custom annotations. The Checker Framework has provided examples of how custom annotations can be used to add greater type safety in Java. In this post, I look at the writing of a ...

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