解释器是直接执行用编程语言编写的指令的程序。只有在执行程序时,才一条一条的解释成机器语言给计算机来执行,所以运行速度不如编译后的程序运行的快。而执行 Java 程序也就是运行程序的字节码,通过 JVM 来解释 Java 字节码。 英文译文:An interpreter is a program that directly executes instructions written in a...
最开始指向c2i适配器入口,在字节码经过编译后会改变地址,指向编译好的代码。 _code:代码入口。当编译器完成编译后会指向编译后的本地代码。 有了上面的知识,方法链接的源码就很容易理解了。如代码清单2-10所示,链接阶段会将i2i_entry和_from_interpreter_entry都指向解释器入口,另外还会生成c2i适配器,将_from_compil...
As you can see,AnotherClasscontains the interface's method in its fifth entry andMyClasscontains it in its second entry. To actually find the correct entry in the virtual method table, a call to a method withinvokeinterfacewill always have to search the complete table without a chance for th...
By default, the JVM compiles the method as a background task, running the method in interpreter mode until the background compilation is finished. The -Xbatch flag disables background compilation so that compilation of all methods proceeds as a foreground task until completed. This option is ...
跳转到Method::_from_interpretered_entry保存的例程处执行,也就是以解释执行运行invokevirtual字节码指令调用的目标方法,关于Method::_from_interpretered_entry保存的例程的逻辑在第6篇、第7篇、第8篇中详细介绍过,这里不再介绍。 如上的汇编语句 mov 0x1b8(%rax,%rbx,8),%rbx 是通过调用调用lookup_virtual_...
UseFastStosb = falsebool UseG1GC = truebool UseGCOverheadLimit = truebool UseHeavyMonitors = falsebool UseInlineCaches = truebool UseInterpreter = truebool UseJumpTables = truebool UseLargePages = falsebool UseLargePagesIndividualAllocation = falsebool UseLoopCounter = truebool UseLoopInvariantCode...
通过调用resolve_klass()和resolve_field()函数后就可拿到这些信息,然后返回到InterpreterRuntime::resolve_get_put()函数继续查看实现逻辑: TosState state = as_TosState(info.field_type()); Bytecodes::Code put_code = (Bytecodes::Code)0; InstanceKlass* klass = InstanceKlass::cast(info.field_holder...
原因是反射、动态代理、CGLib等ByteCode框架、动态生成JSP以及OSGi这类频繁自定义ClassLoader的场景都需要虚拟机具备类卸载的功能,以保证永久代不会溢出。 永久代的垃圾收集主要回收两部分内容:废弃常量和无用的类。 废弃常量的判定:当前系统中没有任何对象的实例,就会被清理出常量池。 无用的类判定: 该类的所有实例...
consumption -- saving approximately eight percent in heap size for typical applications. The first header word contains information such as the identity hash code and GC status information. The second is a reference to the object's class. Only arrays have a third header field, for the array ...
The interpreter returns control to the invoker afterwards.Back to top Final Thoughts In the two sections above, we had a chance to observe how objects are created at the bytecode level, what the opcodes for method invocation are, how parameters are passed to the method invocations and how ...