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 {master,node1,
Background
- Concurrent access to shared data may result in data inconsistency.
- Maintaining data consistency requires a mechanism to ensure the orderly execution of the cooperating process.
Race condition
- Race condition: the situation where several processes access and manipulate shared data concurrently. The final value of the shared data depends upon which process finishes the list.
- To prevent a race condition, concurrent processes must be synchronized.
- On a single-processor machine, we could disable interrupt or use non-preemptive CPU scheduling.
- Commonly described as a critical section problem
Critical Section Requirements
- Mutual Exclusion: if process P is executing in its CS, no other processes can be executing in its CS.
- Process: if no process is executing in its CS and there exist some processes that wish to enter their CS, these processes cannot be postponed indefinitely.
- Bounded waiting: a bound must exist on the number of times that other processes are allowed to enter their CS after a process has made a request to enter its CS.
Critical Section Solutions & Synchronization Tools
- Software Solution.
- Peterson's Solution.
- Bakery algorithm(n process).
- Condition Variable(CV).
- wait() --- Block until another thread call signal() or broadcast() on the CV
- signal() --- Wake up one thread waiting on the CV
- broadcast() --- Wake up all threads waiting on the CV
- Synchronization Hardware.
- Atomic instructions(as one uninterruptible unit).
- Examples: TestAndSet(var), Swap(s,b) .
- Semaphore.
- A tool to generalize the synchronization problem(easier to solve, but no guarantee for correctness).
- A record of how many units of a particular resource is available
- If # record = 1 -> binary semaphore, mutex lock.
- If # record > 1 -> counting semaphore.
- Monitor.
- High-level synchronization construct that allows the safe sharing of an abstract data type among concurrent processes.
- The presentation of the monitor type consists of:
- Declarations of variables whose values define the state of an instance of the type.
- Procedure/functions that implement operations on the type.
- The monitor type is similar to a class in the O.O. language.
- A procedure with a monitor can access only local variables and formal parameters.
- The local variables of a monitor can be used only by the local procedures.
- But, the monitor ensures that only one process at a time can be active within the monitor.
- A similar idea is incorporated into many progs. language:
- Concurrent Pascal, C#, and Java
Monitor condition variables
- To allow a process to wait within the monitor, a condition variable must be declared, as condition x,y.
- The condition variable can only be used with the operations wait() and signal().
- x.wait()
- This means that process invokes this operation until another process invokes it.
- x.signal()
- Resume exactly on the suspended process. If no process is suspended, then the signal operation has no effect(in contrast, the signal always changes the state of a semaphore).
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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