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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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Garbage Collectors

The JVM ships with various options for garbage collection to support a variety of deployment options. With this, we get flexibility in choosing which garbage collector to use for our application.

Serial GC

The Serial collector uses a single thread for garbage collection. The serial collector is not even that powerful compared to other GCs but is useful in a uniprocessor or hardware-constrained environments.

ParNew GC 

The parallel version of the Serial collector, before the emergence of G1 GC, the combination of ParNew and CMS worked together, and ParNew was responsible for the garbage collection of the new generation.

Parallel Scavenge GC 

Aa a young generation GC, compare to other GCs, focuses on the throughput, and another important feature is the auto adjustment strategy to find the best throughput and pause time.

Serial Old GC

Serial Old GC is for the old-generation version of Serial GC. It has two purposes, one is to work with Parallel Scavenge before JDK 5, and the other is an alternative when CMS GC fails.

Parallel Old GC

Parallel Old GC is for the old-generation version of Parallel Scavenge GC. It supports the multi-threaded concurrent collection and has good performance when used with Parallel Scavenge.

CMS GC 

It's called a concurrent low-pause collector, but it consumes more resources and can cause space fragmentation. It has been deprecated since Java 9 and removed in Java 14.

Garbage First GC

As the successor of CMS, G1GC has performed well. Important features include partial collection and memory allocation by region as a pause prediction model.

Shenandoah GC

It is developed by RedHat, so only JDK has this function. Compared with G1 GC, it has three differences.
  • It supports concurrent compact algorithms.
  • It does not use generational collection.
  • It uses connectivity matrices instead of memory sets to record cross-region references.

ZGC

ZGC is a scalable low latency garbage collector and has a very good performance.
It uses techniques including reference coloring, relocation, load barriers, and remapping to implement the concurrent mark-compact algorithm.

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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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