goroutines

goroutines is experimental. It landed after 0.5.1, so import goroutines is not available in that release.

Go-style goroutine runtime for V, implementing the GMP (Goroutine-Machine-Processor) scheduling model translated from the Go runtime (src/runtime/proc.go, runtime2.go, chan.go).

Overview

This module provides lightweight goroutines for V's go keyword, as opposed to spawn which creates OS threads.

GMP Model

G (Goroutine): Lightweight unit of execution with its own stack (~8KB default)
M (Machine): OS thread that executes goroutines
P (Processor): Logical processor with a local run queue (one per CPU core)

Key Features

Work stealing: Idle processors steal work from busy ones
Local run queues: Lock-free per-P queues minimize contention
Global run queue: Overflow and fairness mechanism
Goroutine parking: Efficient blocking/unblocking for channels
G reuse: Dead goroutines are recycled to reduce allocation

Usage

// `go` launches a goroutine (lightweight, scheduled by GMP)
go expensive_computation()

// `spawn` launches an OS thread (traditional V behavior)
spawn blocking_io_task()

Architecture

Translated from Go's runtime source:

Go Source	V Module File	Purpose
`runtime2.go`	`goroutines.v`	Core data structures (G, M, P, Sched)
`proc.go`	`scheduler.v`	Scheduler loop, work stealing, run queues
`proc.go`	`park.v`	gopark/goready, Sudog, WaitQ
`proc.go`	`init.v`	Initialization (schedinit, procresize)
`chan.go`	`chan.v`	Channel implementation
asm (gogo/gosave)	`context_nix.c.v`	Context switching (ucontext)
asm (gogo/gosave)	`context_windows.c.v`	Context switching (Windows fibers)