Category: Parallel Processing

【Rust】rustで子プロセスを生成したい【並列処理】

nixを使います。

nix = “0.16.1”

use nix::unistd::{getpid};

fn main() {
    println!("My id is {}", getpid());
}

My id is 577891

### 子プロセスの生成

use nix::unistd::{fork, getpid, getppid, ForkResult};
use nix::sys::wait::waitpid;
use std::process::exit;

fn main() {
    let num_children = 2;
    start_parent(num_children);
}

fn start_parent(num_children: u32) {
    println!("Parent: I am the parent process");
    println!("Parent PID is {}", getpid());
    for i in 0..num_children {
        run_child();
    }
}

fn run_child() {
    let child_pid = match fork() {
        Ok(ForkResult::Parent {child, ..}) => {
            println!("Main({}) forked child ({})", getpid(), child);
            child
        },
        Ok(ForkResult::Child) => {
            println!("Child({}) PPID is ({})", getpid(), getppid());
            exit(0);
        },
        Err(_) => panic!("fork failed"),
    };

    match waitpid(child_pid, None) {
        Ok(status) => println!(""),
        Err(_) => println!("waitpid() failed"),
    }
}

Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.20s
Running `target/debug/parallel`
Parent: I am the parent process
Parent PID is 579363
Main(579363) forked child (579390)
Child(579390) PPID is (579363)

Main(579363) forked child (579391)
Child(579391) PPID is (579363)

おおおおおおおおお、中々素晴らしい！

【Python】親プロセスと子プロセスを生成する【並列処理】

import os
from multiprocessing import Process

def run_child() -> None:
    print("Child: I am the child process")
    print(f"Child: Child's PID: {os.getpid()}")
    print(f"Child: Parent's PID: {os.getppid()}")

def start_parent(num_children: int) -> None:
    print("Parent: I am the parent process")
    print(f"Parent : Parent's PID: {os.getpid()}")
    for i in range(num_children):
        print(f"Starting Process {i}")
        Process(target=run_child).start()

if __name__ == "__main__":
    num_children = 3
    start_parent(num_children)

$ python3 child_processes.py
Parent: I am the parent process
Parent : Parent’s PID: 576837
Starting Process 0
Starting Process 1
Starting Process 2
Child: I am the child process
Child: Child’s PID: 576838
Child: Parent’s PID: 576837
Child: I am the child process
Child: Child’s PID: 576840
Child: Parent’s PID: 576837
Child: I am the child process
Child: Child’s PID: 576839
Child: Parent’s PID: 576837

### Rustで書きたい

use std::process;
use std::process::Command;

fn main() {
    println!("My id is {}", process::id());

    let mut command = Command::new("ls");
    if let Ok(child) = command.spawn() {
        println!("My id is {}", child.id());
    }
}

Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.15s
Running `target/debug/parallel`
My id is 577522
My id is 577561
Cargo.lock Cargo.toml python src target

Command::newはprocessってよりコマンドのprocessなのでちょっと意図しているものと違うな