Goroutines
Communicating Sequential Processess (CSP)
- Each process a built for sequential execution.
- Data is communicated betewwn processes. No shared memory
- Scale by adding more of the same
- 在 n 個操作系統線程上多工調度 m 個 Goroutines
初始化順序
同一個文件可以有多個 init() function 依出現順序執行, 但是不能被其他函數調用.
Go's Concurrency Tool Set
- goroutines
- channels
- select
- sync package
Goroutines
- Goroutines like user space threads managed by go runtime
- Goroutines extremely lightweight. Goroutines start with 2KB of stack, which grows and shrinks as required. (thread- 8MB of stack)
- 2kb ~ 1GB 的 stack 大小(動態的)
- Low CPU overhead - three instructions per function call.
- Can create hundreds of thounsands of goroutines in the same address space.
- Channels are used for communication of data between goroutines. Sharing of memory can be avoided.
- Context switching between goroutines is much cheaper than thread context switching.
- Go runtime can be more selective in what is persisted for retrievl, how it is persisted, and when the persisting needs to occur.
- Go runtime creates worker OS threads.
- Goroutines runs in the context of OS thread.
- Goroutines & Closures can directly modify variables in the enclosing lexical block.
