The Socket:

  • It has the nature of a pipeline file, similar to a queue, fifO

  • Has a file descriptor

  • Programming interface (API)

IO multiplexing:

  • A single thread handles multiple sockets
  • Core issue: The kernel distributes messages
  • Select model: Threads maintain a list of Socket FDS
  • Epoll model: The kernel maintains an efficient binary search tree

Blocking IO (BIO) :

  • The operation blocks the thread
  • With CPU interrupts, the blocked thread goes to sleep and gives execution permission to another thread
  • Advantages: 1. Does not occupy system resources when blocking. 2. The program is easy to understand
  • Disadvantages: 1. A high concurrency scenario requires a high number of threads (resource usage); 2. Thread switching has costs
  • Scope of application: General high concurrency scenarios can also be considered, especially large parallelism scenarios, such as chat except

Non-blocking IO (NIO) :

  • The operation does not block the thread and returns NULL if not read
  • How it works: A dedicated data structure is responsible for counting I/O as it occurs, allowing programs to listen for changes

Asynchronous IO (AIO) :

  • Asynchronous programming (Future-based)
  • Principle: Scheduling all Future computations using thread pool technology, coroutine technology, usually combined with Epoll and DirectMemory technology

IO N (new) :

  • NIO Channel design

  • DirectMapping

    • It’s essentially a buffer out of the heap

    • Optimization point: Reduce one copy