Reviews Author: Scott Oaks Pub Date: 2014 Publisher: O' Raily ISBN: 5-7 Pages: 425 Language: English Format: PDFSize: 11 Mb Download Download Coding and testing are often considered separate areas of expertise. In this comprehensive guide, author and Java expert Scott Oaks takes the approach that anyone who works with Java should be equally adept at understanding how code behaves in the JVM, as well as the tunings likely to help its performance. You’ll gain in-depth knowledge of Java application performance, using the Java Virtual Machine ( JVM) and the Java platform, including the language and API. Developers and performance engineers alike will learn a variety of features, tools, and processes for improving the way Java 7 and 8 applications perform. The Print Flags Finalcommand will print out hundreds of available tuning flags for the JVM (there are 668 possible flags in JDK 7u40, for example). The vast majority of these flags are designed to enable support engineers to gather more information from running (and misbehaving) applications. It is tempting upon learning that there is a flag called Allocate Prefetch Lines(which has a default value of 3) to assume that value can be changed so that instruction prefetching might work better on a particular processor. But that kind of hit-or-miss tuning is not worthwhile in a vacuum; none of those flags should be changed without a compelling reason to do so. In the case of the Allocate Prefetch Linesflag, that would include knowledge of the application’s prefetch performance, the characteristics of the CPU running the application, and the effect that changing the number will have on the JVM code itself. Java and single- CPU usage To return to the discussion of the Java application—what does periodic, idle CPU mean in that case? It depends on the type of application. If the code in question is a batchstyle application where.
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