backup_vms.py

import threading
import time
import random


class VmsBackup(object):
    def __init__(self):
        self.vms = ['vm01', 'vm02', 'vm03', 'vm04', 'vm05', 'vm06', 'vm07', 'vm08', 'vm09']

    def get_vm_to_backup(self):
        try:
            return self.vms[0]
        except:
            return None

    def set_vm_as_backed_up(self, vm):
        self.vms.remove(vm)

    def run(self, Thread, vm):
        name=threading.current_thread().name
        Thread.activate(name)

        # Aqui eh pra chamar a funcao de backup. To chamando um sleep p ilustrar
        print 'Fazendo backup da vm %s' % vm
        print 'Threads: %s' % str(Thread).strip()
        time.sleep(random.randint(5,10))
        print 'Terminou backup da vm %s' % vm

        Thread.deactivate(name)


class Threads(object):

    def __init__(self):
        super(Threads, self).__init__()
        self.active=[]
        self.lock=threading.Lock()

    def activate(self, name):
        with self.lock:
            self.active.append(name)

    def deactivate(self, name):
        with self.lock:
            self.active.remove(name)

    def count(self):
        with self.lock:
            return len(self.active)

    def __str__(self):
        with self.lock:
            return str(self.active)

if __name__ == '__main__':
    Thread = Threads()
    backup = VmsBackup()
    jobs=[]

    while backup.get_vm_to_backup():
        if threading.activeCount() > 2:
            print 'Esperando thread livre...'
        else:
            vm = backup.get_vm_to_backup()
            job = threading.Thread(target=backup.run, args=(Thread, vm))
            backup.set_vm_as_backed_up(vm)
            job.daemon = True
            job.start()
        time.sleep(1)

    print 'PARECE que terminei :)'