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Install K8S on VM and spring boot integration.

Installation Environment Vmware Workstation pro  It is recommended to use the  snapshot  to store the state of each installation stage to avoid installation failures and causing the installation to start from scratch. Ubuntu 22.04 windows 11 Hardware settings  create 3 VM: 4 cores and 4G memory and 100G capacity Before installing K8s (All use the root user) set host: 192.168.47.135 master 192.168.47.131 node1 192.168.47.132 node2 set root ssh connection: sudo su - echo "PermitRootLogin yes" >> /etc/ssh/sshd_config systemctl restart sshd sudo passwd ssh-keygen for i in {master,node1,node2}; do  ssh-copy-id root@$i; done set Ipvs and conf  create conf file: for i in {master,node1,node2}; do ssh root@$i 'cat << EOF > /etc/modules-load.d/containerd.conf overlay br_netfilter EOF'; done execute conf: for i in {master,node1,node2}; do ssh root@$i 'modprobe overlay;modprobe br_netfilter;'; done create 99-kubernetes-cri.conf file: for i in {maste...
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Annotation

Design pattern

Annotations are an implementation of the decorator design pattern.

The decorator pattern is a design pattern that allows behavior to be added to an individual object, dynamically, without affecting the behavior of other objects from the same class.


Annotations in Java

Annotations, a form of metadata, provide data about a program that is not part of the program itself. Annotations have no direct effect on the operation of the code they annotate.

Annotations have a number of uses:

  • Information for the compiler: Annotations can be used by the compiler to detect errors or suppress warnings
  • Compile-time and deployment-time processing: Software tools can process annotation information to generate code, XML files, and so forth.
  • Runtime processing:  Some annotations are available to be examined at runtime.

Annotations in Spring

Spring uses annotations extensively as a core feature, especially Spring AOP, and almost all the functions we use in Spring rely on Spring annotations.
Essentially, it is a way for adding behavior to existing code without modifying that code.


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OS basic

Table of contents [ hide ] OS architecture The operating system architecture consists of three parts, user mode, kernel mode, and hardware. User mode is for the application to execute the user's program. Kernel mode is to control all the I/O devices and system stability. Storage device hierarchy System call The system call is a kind of software interrupt, including six categories. Process control. File management. Device management. Information maintenance. Communication. Protection. System calls use three methods to pass parameters. Registers. The table in memory. Push onto the stack. A view of operating system services reference: https://www.amazon.com/-/zh_TW/Operating-System-Concepts-Abraham-Silberschatz/dp/1119800366/ref=sr_1_1?keywords=Operating-System-Concepts&qid=1669538704&s=books&sr=1-1
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Cpu scheduling

Table of contents [ hide ] Basic concept The idea of multiprogramming: Keep several processes in memory. Every time one process has to wait, another process takes over the use of the CPU. CPU-I/O burst cycle: Process execution consists of a cycle of CPU execution and I/O wait(i.e., CPU burst and I/O burst). Generally, there is a large number of short CPU bursts and a small number of long CPU bursts An I/O-bound program would typically have many very short CPU bursts. A CPU-bound program might have a few long CPU bursts. CPU scheduler Select from the ready queue to execute(I.e allocates an APU for the selected process) CPU scheduling  decision may take place when a process: Switch from running to waiting state. Switch from running to ready state. Switch from waiting to ready. Terminates. Non-preemptive scheduling: Scheduling under 1 and 4(no choice in terms of scheduling). The process keeps the CPU until it is terminated or switched to the waiting state. Preemptive schedul...
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Java memeory model

The java memory model has multiple areas to do different jobs, this model is in user space because it has no I/O control. There are these parts: Program counter register: For java multi-thread switching different threads, and same functionality as OS counters. (PC) Registers are created every time a new thread is created. The PC holds a pointer to the current statement being executed in its thread. If the currently executing method is 'native', then the value of the program counter register will be undefined. Stack: Private for each thread. It contains method-specific primitive values and references to objects referenced from methods in the heap. Whenever we call a new method, a new block is created on top of the stack which contains values specific to that method Native Method stacks: JVM that supports native methods will have native method stacks. It is used for native methods, and created per thread.  Heap: Heap data area is used to store objects of classes and arrays....
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