08-java11-hotspot-guide.pdf这是官方的原版表中文档。Java11平台中，官

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详细说明：这是官方的原版表中文档。Java11平台中，官方hotspot虚拟机的具体实现的标书。Contents Preface Audience Documentation Accessibility Related documents Conventions 1 Java Virtual Machine Technology Overview 2 Compiler Control Writing Directives 2-1 Compiler Control Options 2-2 Writing a directive file 2-5 Writing a Compiler Directive 2-7 Writing a Method Pattern in a Compiler Directive 2-9 Writing an Inline Directive Option 2-10 Preventing Duplication with the Enable Option 2-10 Understanding Directives 2-11 What is the default directive? 2-12 HoW Directives are Applied to Code? 2-14 Compiler Control and Backward Compatibility 2-15 Commands for Working with Directive Files 2-16 Compiler Directives and the Command Line 2-16 Compiler Directives and Diagnostic Commands 2-17 Getting your Java Process Identification Number 2-17 Adding Directives Through Diagnostic Commands 2-17 Removing Directives Through Diagnostic Commands 2-18 Printing Directives Through Diagnostic Commands 2-18 How Directives are ordered in the directives stack? 2-18 ORACL∈ 3 Garbage Collection 4 Class Data Sharing Class data sharin 4-1 Application Class-Data Sharing 4-2 Regenerating the Shared Archive 4-2 Manually Controlling Class Data Sharing 4-2 5 Java Hotspot Virtual Machine Performance Enhancements Compact Strings 5-1 Tiered Compilation Segmented Code Cache 5-2 Graal: a Java-Based JIT Compiler 5-3 Ahead-of-Time compilation 5-3 Compressed Ordinary object Pointer 5-4 Zero-Based Compressed Ordinary object Pointers 5-5 Escape Analysis 5-5 6 Support for Non-Java Languages Introduction to Non-Java Language Features 6-1 Static and Dynamic Typing 6-2 Statically-Typed Languages Are Not Necessarily Strongly-Typed Languages 6-3 The Challenge of Compiling Dynamically-Typed Languages 6-3 The invokedynamic Instruction 6-5 Defining the Bootstrap Method 6-6 Specifying Constant Pool Entries 6-7 Example Constant Pool 6-7 Using the invokedynamic Instruction 6-8 7 Signal Chaining 8 Native Memory Tracking Key features 8-1 Using Native Memory T racking 8-1 Enabling nmt 8-1 Accessing nmt data using icmd 8-2 ORACLE Obtaining NMT Data at VM EXit 8-2 9 DTrace Probes in Hotspot VM Using the hotspot Provider 9-1 VM Lifecycle Probes 9-1 Thread Lifecycle probes 9-2 Classloading Probes 9-2 Garbage Collection Probes 9-3 Method Compilation Probes 9-4 Monitor probes 9-5 Application Tracking Probes 9-6 Using the hotspot jni Provider 9-7 Sample Dtrace Probes 9-7 10 Fatal Error Reporting Error Report example 10-1 11 Java Virtual Machine Related Resources Tools 11-1 ORACL∈ Preface Preface This document provides information about the features supported by java virtual Machine technology Audience This document is intended for experienced developers who build applications using the Java Hotspot technology Documentation Accessibility For information about Oracle's commitment to accessibility, visit the Oracle AccessibilityProgramwebsiteathttp://www.oracle.com/pls/topic/lookup? ctx=acc&id=docacc Access to Oracle Support Oracle customers that have purchased support have access to electronic support throughMyOracleSupportForinformationvisithttp://www.oracle.com/pls/topic/ lookup?ctx=acc&id=infoorvisithttp://www.oracle.com/pls/topic/ookup?ctx=acc&id=trs if you are hearing impaired Related documents See JDK 1l Documentation for other JDK 12 guides Conventions The following text conventions are used in this document Convention MeanIng boldface Boldface type indicates graphical user interface elements associated with an action or terms defined in text italic I talic type indicates book titles, emphasis, or placeholder variables for thich you supply particular values .andspace Monospace type indicates commands within a paragraph, URLS, code in examples, text that appears on the screen, or text that you enter ORACLE 1 Java virtual machine Technology Overview This chapter describes the implementation of the java virtual Machine (JvM) and the main features of the java Hot spot technology Adaptive compiler: A standard interpreter is used to launch the applications When the application runs the code is analyzed to detect performance bottlenecks, or hot spots. The Java HotSpot VM compiles the performance-critical portions of the code for a boost in performance, but does not compile the seldom- used code(most of the application). The Java Hot Spot VM uses the adaptive compiler to decide how to optimize compiled code with techniques such as g Rapid memory allocation and garbage collection Java Hotspot technology provides rapid memory allocation for objects and fast, efficient, state-of-the-art garbage collectors Thread synchronization Java Hotspot technology provides a thread- handling capability that is designed to scale for use in large, shared-memory multiprocessor servers In oracle Java Runtime Environment JRE)8 and earlier, difterent implementations of the JVM, (the client VM, server VM, and minimal VM) were supported for configurations commonly used as clients, as servers, and for embedded systems Because most systems can now take advantage of the server VM, the oracle Java Runtime Environment (JRE )9 provides only that VM implementation ORACLE Compiler Control Compiler Control provides a way to control Java Virtual Machine JVM) compilation through compiler directive options. The level of control is runtime- manageable and method specific a compiler directive is an instruction that tells the ]Vm how compilation should occur a directive provides method-context precision in controlling the compilation process You can use directives to write small, contained, JVM compiler tests that can run without restarting the entire JVM. You can also use directives to create workarounds for bugs, in the JVM compilers You can specity a file that contains compiler directives when you start a program through the command line. You can also add or remove directives from an already running program by using diagnostic commands Compiler Control supersedes and is backward compatible with Compile Command TopICS Writing Directives iting a directive File Writing a Compiler Directive Writing a Method Pattern in a Compiler Directive Writing an Inline Directive Option Preventing Duplication with the Enable Option Understanding Directives What is the default directive? How Directives are Applied to Code? Compiler Control and Backward Compatibility Commands for Working with directive Files Compiler directives and the command line Compiler Directives and Diagnostic Commands How Directives are ordered in the directives stack? Writing Directives This topic examines Compiler Control options and steps for writing directives from those options Topics: Compiler Control Options ORACLE Chapter 2 Writing Directives Writing a directive Flle Writing a Compiler Directive Writing a Method Pattern in a Compiler Directive Writing an Inline Directive Option Preventing duplication with the Enable Option Compiler Control Options Options are instructions for compilation. Options provide method-context precision Available options vary by compiler and require specific types of values Table 2-1 Common Options option Description Value Type Default value Enable Hides a directive and bocl true ders it unmatchable if it is set to fal This option is useful for preventing option ng duplication. See Preventing Duplication with the enable ptio Exclude Excludes methods bocl false from compila BreakAtExecute Sets a breakpoint to bocl false stop execution at the beginning of the specified methods then debugging the JVM BreakAt Compile Sets a breakpoint to bocl false stop compilation at the beginning of the specified methods when debugging the JVM Log Places only the false specified methods in a log. You must first set the command-line option -XX +L○ g Compilatio The default value -alse places all compiled methods in a og ORACLE 2-2 Chapter 2 Writing Directives Table 2-1 (Cont )Common options Option Description Value Type Default value Printassembl Prints assembly code bool fa⊥se for bytecoded and native methods by using the external disassembler. so library PrintInlining Prints which methods bool false are inlined, and where PrintNMethods Prints nmethods as boo false they are generated BackgroundCompila Compiles methods as bool true tion a background task Methods run in interpreter mode until the background compilation finishes The value false compiles methods as a foreground task Replayinline Enables the sai bool false CIReplay functionality as the corresponding global option, but on a per-method basis DumpReplay Enables the same bool false CIReplay functionalit as the corresponding global option, but on a per-method basis DumpInline Enables the same bool false CIReplay functionalit as the corresponding global option, but on a per-method basis CompilerDirective Disregards all bool false sIgnoreCompileCom Complecommands Disableintrinsic Disables the use of cstr No default value intrinsics based on method-matchin g criteria in⊥ine Forces or prevents [] No default value inlining of a method based on method matching criteria. See Writing an inline Directive Option ORACL∈

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