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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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Thread and concurrency

Thread

Thread is a lightweight process, a basic unit of CPU utilization.

All threads belonging to the same process share:

  • Code section.
  • Data section.
  • OS resources(e.g. open files and signals)
Each thread has its own(thread control block):
  • Thread ID.
  • Program counter.
  • Register set.
  • A tack.
Benefits of multithreading:
  • Responsiveness.
  • Resource sharing.
  • Utilization of NP arch.
  • Economy.

User vs Kernel threads

User threads

  • Thread management is done by the user-level thread library.
    • POSIX Pthreads.
    • Win32 threads.
    • Java threads.
  • Thread library provides support for thread creation, scheduling, and deletion.
  • Generally fast to create and manage.
  • If the kernel is single-threaded, a user-thread block -> entire process blocks even if other threads are ready to run.

Kernel threads

  • Supported by the kernel(OS) directly.
    • Windows 2000(NT)
    • Solaris
    • Linux
    • Tr64 UNIX
  • The kernel performs thread creation, scheduling, etc.
  • Generally slower to create and manage.
  • If a thread is blocked, the kernel can schedule another thread for execution.

Multithreading models

  • Many-to-One: Many user-level threads mapped to a single kernel thread.
  • One-to-One: Each user-level thread maps to the kernel thread.
  • Many-to-Many:  Multiplexes many user-level threads to a smaller or equal number of kernel threads

Thread pools

Create a number of threads in the pool where they await work.
Advantages:
  • Usually slightly faster to service a request with an existing thread than create a new thread.
  • Allows the number of threads in the application(s) to be bound to the size of the pool.

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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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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SOLID

SOLID is the fundamental and core principle of OOP. Single-Responsibility Principle High cohesion: A module preferably has only one business logic. Low coupling:   The different modules work independently and are connected by simple protocols to minimize side effects. Open-Closed Principle Open for extension:  It is easy to extend new functions with existing code. Close for modification:  Do not modify existing classes to ensure stable functions. Liskov-Substitution Principle A superclass should be replaceable with objects of its subclasses without breaking the application. Interface-Segregation Principle Clients only depend on the interfaces they need, don't use the "big" interface to contain everything. Dependence-Inversion Principle The program should depend upon abstractions, not concretions. reference: https://en.wikipedia.org/wiki/SOLID https://blog.knoldus.com/what-is-liskov-substitution-principle-lsp-with-real-world-examples/ https://github.com/hollischuang/toBeTo...
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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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