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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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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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JVM Tools

Table of contents [ hide ]  Java has many useful tools for debugging at runtime or analyzing an application after it has crashed. Commands jps - JVM process Status Tool Same as the Linux command ps, only to find the process under the JVM. jinfo - Configuration Info for Java Show and adjust the JVM arguments. jmap - Memory Map for Java Getting a memory error dump is the most common technique used at runtime. The dump file can be used to analyze the cause of the failure. jstack - Stack trace for Java Check the thread runtime status. GUI VisualVM VisualVM is a tool that provides a visual interface for viewing detailed information about Java applications while they are running on a Java Virtual Machine (JVM). Memory Analyzer (MAT) The Eclipse Memory Analyzer is a fast and feature-rich Java heap analyzer that helps you find memory leaks and reduce memory consumption. reference: https://www.amazon.com/depth-understanding-Java-Virtual-Machine/dp/7111641248 https://en.wikipedia.org/w...
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Garbage Collectors

Table of contents [ hide ] 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...
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