One：JVM Practical thinking map （ Full version ）

Two： approach Java

summary + Java Technical system +Java The history of +Java Virtual machine family ：（Sun Classic/Exact VM、HotSpot VM、Mobile/Embedded VM、BEA JRockit/IBM J9 VM、BEA Liquid VM/Azul VM、Apache Harmony/Google Android Dalvik VM、Microsoft JVM And others ）+ expectation Java The future of Technology + actual combat ： Compile it yourself JDK

Three： Automatic memory management

Java Memory area and memory overflow exception ： Run time data area ：（ Program counter +Java Virtual machine stack + Native Method Stack + Java Pile up + Method area + Runtime constant pool + Direct memory ）tSpot Exploring virtual machine objects + actual combat ：OutOfMemoryError abnormal （Java Heap overflow + Virtual machine stack and local method stack overflow + Method area and runtime constant pool overflow + Local direct memory overflow ）

** Garbage collector and memory allocation strategy ：** The object is dead. ？+ Garbage collection algorithm +HotSpot The algorithm details of the implementation of + The classic garbage collector + Low latency garbage collector + Choose the right garbage collector + actual combat ： Memory allocation and recycling strategy

** Virtual machine performance monitoring 、 Troubleshooting tools ：** Basic troubleshooting tools + Visual fault handling tool +HotSpot Virtual machine plug-ins and tools

** Tuning case analysis and practice ：** case analysis ：（ Program deployment strategy on large memory hardware + Memory overflow caused by synchronization between clusters + Overflow error due to out of heap memory + External commands cause the system to slow down + The server virtual machine process crashed + Improper data structure leads to excessive memory consumption + from Windows Long pause caused by virtual memory + Long pause caused by safety point ）

Four： Virtual machine execution subsystem

** Class file structure ：** The cornerstone of irrelevance +Class Class file structure + Introduction to bytecode instruction + Public design , Private implementation +Class The development of document structure

** Virtual machine class loading mechanism ：** Class load time + The process of class loading + Class loader +Java Modular system

VM bytecode execution engine ：? Runtime stack frame structure + Method call + Dynamic type language support + Stack based bytecode interpretation execution engine

** Class loading and execution subsystem cases and actual combat ：** case analysis ：( Tomcat： The orthodox classloader Architecture + OSGi： Flexible classloader Architecture + Bytecode generation technology and implementation of dynamic proxy +Backport Tools ：Java Your time machine )+ actual combat ： Do it yourself to realize remote execution function

Five： Program compilation and code optimization

** Front end compilation and optimization ：**Javac compiler +Java The taste of grammar sugar （ Generic + Automatic boxing 、 Unpacking and traversing cycle + Conditional compilation ）+ actual combat ： Plug in annotation processor

** Back end compilation and optimization ：** Just in time compiler + Ahead of time compiler + Compiler optimization technology + In depth understanding of Graal compiler

Six： Efficient concurrent

**Java Memory model and thread ：** Efficiency and consistency of hardware +Java Memory model （ Main memory and working memory + Inter memory interaction + about volatile Special rules for type variables + in the light of long and double Special rules for type variables + Atomicity 、 Visibility and order + Antecedent principle ）+Java With threads （ Implementation of threads +Java Thread scheduling + State transition ）+Java With the process

Is that enough ？ No , It's not enough ！

Getting familiar with Ali's interview questions in previous years in advance must be of great help to the interview , But as a technical profession , Having solid skills in hand is the most useful weapon for you to face the interviewer , This is self-confidence emanating from the inside .

The most time I spent preparing for Ali was learning technology , It accounts for... Percent of all my study plans 70, These are some learning notes that I think are very good during my study , And learning videos are   You can click here for free Of ！

Why should I write this article , In fact, I think learning can't stop , Share with you on the Internet , Discuss together , You can't just meet more of the same people , You can broaden your horizons , Learn more technology , I will be in csdn、 Blog 、 Share technology on websites such as nuggets , This is also a way of learning .

I'll share it with you today , Thank you for your attention , I will share more dry goods to you in the future ！