Python 多线程 threading.Thread 同时最多有 n 个线程

import threading
import numpy as np
import time

class BuildThread(threading.Thread):
	def __init__(self, name, alist):
		threading.Thread.__init__(self)
		self.alist = alist

	def run(self):
		self.alist.append(np.random.random_integers(1,10))
		time.sleep(1)

thread_num = 4 # 想要多少写多少

g_collect = []
threads = []


start_time = time.time()

for thread in range(thread_num):
	# 不使用多线程
	# g_collect.append(np.random.random_integers(1,10))
	# time.sleep(1)
	
	# 使用多线程
	_thread = BuildThread('Thread-1', g_collect)
	threads.append(_thread)
	_thread.start()

for thread in threads: # 保护：必须所有threads里的线程结束才可以进入下一步
	thread.join()

end_time = time.time()
run_time = end_time - start_time

print(g_collect)
print('run time: ', run_time)

import threading
import numpy as np
import time


class BuildThread(threading.Thread):
    def __init__(self, name, alist, threads):
        threading.Thread.__init__(self)
        self.alist = alist
        self.threads = threads

    def run(self):
        self.alist.append(np.random.random_integers(1,10))
        time.sleep(1)
        self.threads.remove(self)



thread_num = 10

g_collect = []
threads = []

start_time = time.time()
for thread in range(thread_num):
	
    while len(threads) >= 4: # 同时最多有4个线程
        pass
	
    _thread = BuildThread('Thread-{}'.format(threads), g_collect, threads)
    threads.append(_thread)
    _thread.start()


print(threads)

end_time = time.time()
run_time = end_time - start_time

print(g_collect)
print('run time: ', run_time)