启动线程太多，导致抛出异常： cant't start new thread，需要限制start线程数
import threading
thread_list = []
pool_sema = threading.BoundedSemaphore(10)
def test():
with pool_sema:
print('test....')
time.sleep(1)
if __name__ == '__main__':
for i in range(pow(10, 6)):
t = threading.Thread(target=test)
t.start()
thread_list.append(t)
print('当前线程数: {0}'.format(threading.active_count()))
while threading.active_count() > pow(10, 4):
time.sleep(0.001)
for i in thread_list:
i.join()
