🔥 Add OnPrefork Hooks so you can get the PID of the child process.

[tohutohu]

Add Hooks that can get the PID of a child process forked from the master process.
Currently, in the Prefork mode of fiber, the PID of the child process forked from the master process cannot be obtained, so CPU Affinity cannot be set automatically using commands such as taskset.
To maximize performance in Prefork mode, each child process should be pinned to a specific CPU core.
To make this possible, I will add a new Hooks.

Usage

func main() {
	app := fiber.New(fiber.Config{
		Prefork: true,
	})

	app.Hooks().OnFork(func(pid int) error {
		fmt.Printf("Forked child process %d\n", pid)
		return nil
	})

	app.Get("/", func(c *fiber.Ctx) error {
		return c.SendString("Hello, World 👋!")
	})

	app.Listen(":3000")
}

output

Forked child process 18331
Forked child process 18332
Forked child process 18333
Forked child process 18334
Forked child process 18336
Forked child process 18338
Forked child process 18341
Forked child process 18350
Forked child process 18355
Forked child process 18365
Forked child process 18383
Forked child process 18388

 ┌───────────────────────────────────────────────────┐  ┌───────────────────────────────────────────────────┐
 │                   Fiber v2.35.0                   │  │ Child PIDs ... 18331, 18332, 18333, 18334, 18336  │
 │               http://127.0.0.1:3000               │  │ 18338, 18341, 18350, 18355, 18365, 18383, 18388   │
 │       (bound on host 0.0.0.0 and port 3000)       │  └───────────────────────────────────────────────────┘
 │                                                   │
 │ Handlers ............. 2  Processes .......... 12 │
 │ Prefork ........ Enabled  PID ............. 18325 │
 └───────────────────────────────────────────────────┘

[welcome]

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[tohutohu]

The commit above is for triggering GitHub Actions again.
The previous error doesn't appear to be caused by this PR’s change, do you know why?

[efectn]

The commit above is for triggering GitHub Actions again. The previous error doesn't appear to be caused by this PR’s change, do you know why?

Some timeout tests are buggy.

[tohutohu]

Thank you very much. It would be helpful if you could approve Workflow.

[ReneWerner87]

@tohutohu

• pls add documentation under https://github.com/gofiber/docs

[tohutohu]

Sorry for the late reaction. I've added documentation and submitted a PR.

[welcome]

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