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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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Proxy

Proxy in design pattern

The proxy pattern is a software design pattern, as a wrapper or agent object that is being called by the client to access the real serving object behind the scene.

There are two advantages:

  • Provides access control for real objects.
  • Provides additional functionality when accessing real objects.

And there are two types of proxy:
  • Static proxy: proxies are created manually. Java example on GitHub.
  • Dynamic proxy: proxies are created by JDK Proxy or CGLib Proxy with reflection.

JDK proxy

Before the proxy object is created, it must implement the invoke method of the InvocationHandler, which is invasive to the target object.
JDK Dynamic proxy can only proxy by the interface (so your target class needs to implement an interface, which is then also implemented by the proxy class)

CGLib proxy

The proxy object is created by implementing the intercept method of MethodInterceptor, and the target object does not need to implement this method but implements it through subclasses to reduce code invasion.

It is a byte instrumentation library used in many Java frameworks such as Hibernate or Spring. The bytecode instrumentation allows manipulating or creating classes after the compilation phase of a program.


reference:

https://en.wikipedia.org/wiki/Proxy_pattern

https://stackoverflow.com/questions/10664182/what-is-the-difference-between-jdk-dynamic-proxy-and-cglib

https://www.cnblogs.com/carpenterlee/p/8241042.html

https://www.baeldung.com/cglib

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GC Basic Algorithm

Theory Most GCs follow the theory of generational collection, which is based on the following two: Week generational hypothesis:  Most of the objects are short-living. Strong generational hypothesis:  The more times an object survives GC, the harder it is to die. Mark-Sweep After the marking phase has been completed all space occupied by unvisited objects is considered free and can thus be reused to allocate new objects. There may exist plenty of free regions but if no single region is large enough to accommodate the allocation, the allocation is still going to fail. Mark-Copy To avoid excessive fragmentation, it splits the space into two parts and copies the surviving objects into empty parts. The disadvantage is the need for one more memory region, which should be large enough to accommodate survived objects. Mark-Compact Like mark-copy, it doesn't require another space to copy but a more complex operation to move the object. Reachability analysis First, GC defines some spe...
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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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