我想创建简单的线程队列。
线程将从请求后开始
我创建了没有请求的简单示例。我尝试加入线程,但无法按我的意愿工作。
def a():
print('start a')
sleep(5)
print('end a')
def b():
print('start b')
sleep(5)
print('end b')
t = Thread(target=a)
t.start()
t.join()
print('test1')
t = Thread(target=b)
t.start()
t.join()
print('test2')
代码结果:
start a
end a
test1
start b
end b
test2
期望:
start a
test1
end a
start b
test2
end b
我知道我可以在加入之前打印('test1'),但是当我使用发布请求时,线程可以在打印('test1')时启动
t.start()
print('test1') <- here comes post request
t1.start()
print('test2')
t1.join()
t.join()
在这种情况下,线程将并行运行
答案 0 :(得分:1)
您可以向timeout
传递一个join()
参数,这将阻塞调用线程最多timeout
秒。 “最大”,因为线程可以提前终止。如果不传递超时,它将一直阻塞直到线程完成。因此,在您的示例中,您需要做的是两次将线程加入一次,第一次超时,该超时允许打印test1
。
from threading import Thread
from time import sleep
def a():
print('start a')
sleep(5)
print('end a')
def b():
print('start b')
sleep(5)
print('end b')
t = Thread(target=a)
t.start()
t.join(0.1)
print('test1')
t.join()
t = Thread(target=b)
t.start()
t.join(0.1)
print('test2')
t.join()
输出:
start a
test1
end a
start b
test2
end b
除此之外,如果您担心的只是限制每秒请求数,那么我怀疑这是否是一种好方法。您可以重用线程,而不必为每个请求重新创建线程,这将节省创建开销。您可以使用ThreadPool并以指定的心跳向池中发出请求任务。
import logging
from time import sleep
from multiprocessing.pool import ThreadPool
def make_request(*args):
logger.debug(f'making request number {args[0]}')
sleep(5)
def init_logging(log_level=logging.DEBUG):
fmt = '[%(asctime)s %(levelname)-8s %(threadName)s' \
' %(funcName)s()] --- %(message)s'
logging.basicConfig(format=fmt, level=log_level)
if __name__ == '__main__':
N_THREADS = 5
N_REQUESTS = 10
arguments = [*zip(range(N_REQUESTS))] # [(0,), (1,), (2,) ...]
init_logging()
logger = logging.getLogger()
with ThreadPool(N_THREADS) as pool:
for args in arguments:
pool.apply_async(make_request, args=args)
sleep(1) # heartbeat
示例输出:
[2018-09-09 03:17:06,303 DEBUG Thread-1 make_request()] --- making request number 0
[2018-09-09 03:17:07,304 DEBUG Thread-2 make_request()] --- making request number 1
[2018-09-09 03:17:08,306 DEBUG Thread-3 make_request()] --- making request number 2
[2018-09-09 03:17:09,307 DEBUG Thread-4 make_request()] --- making request number 3
[2018-09-09 03:17:10,308 DEBUG Thread-5 make_request()] --- making request number 4
[2018-09-09 03:17:11,309 DEBUG Thread-1 make_request()] --- making request number 5
[2018-09-09 03:17:12,310 DEBUG Thread-2 make_request()] --- making request number 6
[2018-09-09 03:17:13,311 DEBUG Thread-3 make_request()] --- making request number 7
[2018-09-09 03:17:14,312 DEBUG Thread-4 make_request()] --- making request number 8
[2018-09-09 03:17:15,313 DEBUG Thread-5 make_request()] --- making request number 9
Process finished with exit code 0