django parallel migrate(per host)

parallelmigrate.py

# coding: utf-8
from __future__ import absolute_import, unicode_literals

from collections import defaultdict
import commands
from multiprocessing import Process

from django.conf import settings
from django.core.management.base import BaseCommand


class Command(BaseCommand):
    
    def handle(self, *args, **options):
        hosts = self._get_hosts()
        processes = self._gen_processes(hosts)

        print("start.")
        self._start_processes(processes)
        self._join_processes(processes)
        print("end.")
    
    def _get_hosts(self):
        hosts = defaultdict(dict)
        
        for name, database in settings.DATABASES.items():
            hosts[database['HOST']][name] = database
            
        return hosts
        
    def _gen_processes(self, hosts):
        return [
            Process(target=execute, args=(database.keys(),))
            for database in hosts.values()
        ]

    def _start_processes(self, processes):
        for process in processes:
            process.start()

    def _join_processes(self, processes):
        for process in processes:
            process.join()


def execute(names):
    for name in names:
        print("migrate --database={}".format(name))
        _, output = commands.getstatusoutput("./manage.py migrate --database={}".format(name))
        print(output)