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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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Deadlocks

 A set of the blocked processes each holding some resources and waiting to acquire a resource held by another process in the set.

Necessary conditions

All four conditions must hold for possible deadlock:
  • Mutual exclusion: 
    • Only 1 process at a time can use a resource.
  • Hold and wait:
    • A process holding some resources is waiting for another resource
  • No preemption:
    • A resource can be only released by a process voluntarily.
  • Circular wait:
    • There exists a set {P0,P1…} of waiting processes such that
      • P0 -> P1 -> P2 …..Pn -> P0

Handling Deadlocks

  • Ensure the system will never enter a deadlock state.
    • Deadlock prevention: ensure that at least one of the 4 necessary conditions cannot hold.
    • Deadlock avoidance: dynamically examines the resources allocation state before allocation.
  • Allow to enter a deadlock state and then recover.
    • Deadlock detection.
    • Deadlock recovery.
  • Ignore the problem and pretend that deadlock never occurs in the system.
    • Use by most operating systems, including UNIX…

Avoidance algorithms

  • A single instance of the resource type.
    • Resource-allocation graph(RAG) algorithm based on circle detection.
  • Multiple instances of the resource type.
    • Banker's algorithm is based on safe sequence detection.

Deadlock Detection

Single instance of each resource type.
  • Convert request/assignment edges into wait-for graph
  • Deadlock exists if there is a cycle in the wait-for graph

Deadlock Recovery

  • Process termination.
  • Resource preemption.

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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