Laravel:如何在子进程中通过Eloquent更新MySQL？

Question

我写了一个Laravel Command,它会分叉一些子进程.子进程将通过Eloquent更新数据库.

码:

<?php

namespace App\Console\Commands;

use App\Console\BaseCommand;
use App\Item;
use Illuminate\Console\Command;

class Test extends Command
{
    /**
     * The name and signature of the console command.
     *
     * @var string
     */
    protected $signature = 'test';

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Command description';

    /**
     * Create a new command instance.
     *
     * @return void
     */
    public function __construct()
    {
        parent::__construct();
    }

    /**
     * Execute the console command.
     *
     * @return mixed
     */
    public function handle()
    {
        Item::first();
        $children = [];
        for($i = 0; $i < 5; $i++) {
            $pid = pcntl_fork();
            if ($pid == -1) {
                die('pmap fork error');
            } else {
                if ($pid) {
                    $children[] = $pid;
                } else {
                    Item::first(); exit;
                }
            }
        }
        foreach ($children as $child) {
            pcntl_waitpid($child, $status);
        }
    }
}

运行我的代码:

vagrant@homestead:~/ECAME$ php artisan test


  [Illuminate\Database\QueryException]
  Packets out of order. Expected 1 received 116. Packet size=6255201 (SQL: select * from `items` where `items`.`deleted_at` is null limit 1)



  [Illuminate\Database\QueryException]
  Packets out of order. Expected 1 received 100. Packet size=6238815 (SQL: select * from `items` where `items`.`deleted_at` is null limit 1)



  [Illuminate\Database\QueryException]
  Packets out of order. Expected 1 received 0. Packet size=2816 (SQL: select * from `items` where `items`.`deleted_at` is null limit 1)



  [Illuminate\Database\QueryException]
  Packets out of order. Expected 1 received 116. Packet size=6381412 (SQL: select * from `items` where `items`.`deleted_at` is null limit 1)



  [ErrorException]
  Packets out of order. Expected 1 received 100. Packet size=6238815



  [ErrorException]
  Packets out of order. Expected 1 received 116. Packet size=6381412



  [ErrorException]
  Packets out of order. Expected 1 received 116. Packet size=6255201



  [ErrorException]
  Packets out of order. Expected 1 received 0. Packet size=2816

这背后的原因是什么？以及如何在子进程中通过Eloquent更新MySQL？

PS:

我认为这个问题的原因是,所有子进程都使用从父进程分叉的相同MySQL连接.

如果我在调用Item::first()之前没有调用父进程fork(),那么它运行良好.(在我的实际用例中,我不能这样做......在fork子进程之前,父进程将对MySQL做很多事情.)

因为在这种情况下,MySQL连接不会在父进程中初始化,因此每个子进程都将自己初始化连接.

那么,如果是这种情况,如何在分叉后为每个子进程初始化一个新的MySQL连接？

Answer 1

由于它是关于连接死亡的全部,您可以通过简单地重新连接到数据库来解决这个问题.

use Illuminate\Support\Facades\DB;

[...]

public function handle()
{
    User::first();

    $children = [];

    for ($i = 0; $i < 5; $i++) 
    {
        $pid = pcntl_fork();

        if ($pid == -1) 
        {
            die('pmap fork error');
        } 
        else 
        {
            if ($pid) 
            {
                $children[] = $pid;
            } 
            else
            {
                DB::connection()->reconnect(); // <----- add this
                User::first(); exit;
            }
        }
    }

    foreach ($children as $child) 
    {
        pcntl_waitpid($child, $status);
    }
}

我在Laravel 5.6中测试了这个并且它可以工作.