java 1 7 virtual machine

Local method stack when a thread calls the native method, it enters a world not restricted by Java virtual machine. It can use registers of the local processor to allocate memory on any number of local stacks or use any type of stacks.The local method interface uses a certain type of local method stack. When the thread calls the

Java Virtual Machine (1) runtime data area 1. There is a "high wall" between Java and C ++ that is surrounded by the dynamic memory allocation and garbage collection technology. The people inside the wall want to go in, but they w

of short-term objects can be recovered as much as possible, reducing medium-term objects, while older generations store long-lived objects.Fragmentation problems caused by smaller heapsThe heap is not compressed because the old generation of concurrent collectors uses tags and clears the algorithm. When the collector recycles, he merges the adjacent space so that it can be assigned to a larger object. However, when the heap space is small, after a period of time, "fragmentation" occurs, if the

Notes 1. Compile Order: Compiler virtual Machine virtual machine Java source file *.java-------> Bytecode *.class------> class Loader--- gt; execution engine A. class file can contain

this almost unique method of knowing how the JVM garbage collector works in a production environment. The generally acceptable GC overhead is capped at 5%, which is trivial if you know the cost of the system for GC pauses and can take action to minimize the cost.Conclusion: In the capacity range, as much as possible to obtain the system in the production environment of the operational data, you will find that it is a new world.SummarizeHopefully the above conclusions will help you to better gra

, linking and initialization) The class loading subsystem is not only responsible for locating and loading class files, but also does many other things according to the following strict steps: (for details, see Chapter 7 "class lifecycle ") 1) load: Find and import binary information of the specified type (class and Interface)2) connection: verification, preparation, and resolution① Verification: ensure the

garbage collection, first understand the internal architecture of the Java Virtual machine, as shown in The middle dashed box part is the run Time data region, which consists of 5 parts, namely the method area, heap, stack, program counter and local method stack. 1. Program counter For a running

) { return (a + b) * (a - b); } public static void main(String[] args) { Hello t = new Hello(); System.out.print(t.foo(5, 3)); }} Take the foo method in this Code as an example. After compiling it into a class file, decompile the class file to view the JAVA bytecode: Code: 0: iload_1 1: iload_2 2: iadd 3: iload_1 4: iload_2 5: isu

is limited. The sum of the Java heap and direct memory is still limited by the maximum memory given by the operating system"5" garbage collection system---an important part of the >java virtual machine.---> Recycle garbage space on the method area, Java heap, direct memory.

execution.Load:The load phase is a phase in the class loading mechanism, which is often referred to as "loading," and is mainly done by:1. Obtain a binary byte stream that defines this class by "full name of Class"2. Convert the static storage structure represented by the byte stream to the run-time data structure of the method area3. Generate a Java.lang.Class object representing this class in the Java he