使用Python 3.6和aiohttp和from aiohttp import ClientSession
import asyncio, ssl, time
base_url = 'https://my-base-url.com/api'
async def fetch(session, id):
query_params = {'qp1':'v1','qp2':'v2', 'id': id}
async with session.get(base_url, params=query_params, ssl=ssl.SSLContext()) as response:
res_json = await response.json()
if response.status == 200:
time.sleep(2)
min_rating = res_json.get('minRating')
max_rating = res_json.get('maxRating')
print("id = %s, min = %s, max = %s" % (id, min_rating, max_rating))
async def run(ids):
tasks = []
async with ClientSession() as session:
for id in ids:
task = asyncio.ensure_future(fetch(session, id))
tasks.append(task)
responses = await asyncio.gather(*tasks)
return responses
if __name__ == '__main__':
ids = [123, 456, 789]
future = asyncio.ensure_future(run(ids))
event_loop = asyncio.get_event_loop()
event_loop.run_until_complete(future)
print("\n\ndone")
，我编写了一个简单的异步程序：
time.sleep(2) fetch(session, id)中的sleep使得该程序似乎不是异步的，因为它得到一个响应，睡眠，另一个响应，睡眠等等。当我删除睡眠调用时，它似乎是异步/并发的，因为响应以随机顺序返回。 import sys
from PyQt5.QtCore import Qt, QRectF
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QCalendarWidget, QApplication
class CalendarWidget(QCalendarWidget):
def paintCell(self, painter, rect, date):
painter.setRenderHint(QPainter.Antialiasing, True)
if (date.day() == 1) or (date.day() == 15):
painter.save()
painter.drawRect(rect)
painter.setPen(Qt.blue)
painter.drawText(QRectF(rect), Qt.TextSingleLine|Qt.AlignCenter, str(date.day()))
painter.restore()
else:
QCalendarWidget.paintCell(self, painter, rect, date)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = CalendarWidget()
w.show()
sys.exit(app.exec_())
在这种情况下正在做什么？是否锁定所有线程？为什么它看起来是顺序的而不是并行的？
答案 0 :(得分：5)
time.sleep(2)是一个同步（阻塞）调用，因此要停止它的异步调用，应使用await asyncio.sleep(2)，它将“释放”资源。