我有一个运行一些 shell 命令的网络服务器。该命令通常需要几秒钟,但在某些情况下需要更多时间,在这种情况下客户端(不是网络浏览器或curl)会断开连接。
我无法修复客户端,所以我考虑修复服务器。它基于 Tornado 框架。我使用tornado.gen.with_timeout函数重写了它,但由于某种原因它不能按我的预期工作。我将超时设置为 5 秒,因此在查询服务器时,我希望得到“在 X 秒内完成”(其中 X < 5)或“已经花费了超过 5 秒......仍在运行”。在这两种情况下,我希望在 5 秒内得到响应。
这是代码:
import os
import json
import datetime
import random
from tornado.ioloop import IOLoop
from tornado.web import RequestHandler, Application
from tornado.gen import coroutine, with_timeout, TimeoutError, Return
@coroutine
def run_slow_command(command):
res = os.system(command)
raise Return(res)
class MainHandler(RequestHandler):
@coroutine
def get(self):
TIMEOUT = 5
duration = random.randint(1, 15)
try:
yield with_timeout(datetime.timedelta(seconds=TIMEOUT), run_slow_command('sleep %d' % duration))
response = {'status' : 'finished in %d seconds' % duration}
except TimeoutError:
response = {'status' : 'already took more than %d seconds... still running' % TIMEOUT}
self.set_header("Content-type", "application/json")
self.write(json.dumps(response) + '\n')
def make_app():
return Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
app = make_app()
app.listen(8080)
IOLoop.current().start()
这是curl 的输出:
for i in `seq 1 5`; do curl http://127.0.0.1:8080/; done
{"status": "finished in 15 seconds"}
{"status": "finished in 12 seconds"}
{"status": "finished in 3 seconds"}
{"status": "finished in 11 seconds"}
{"status": "finished in 13 seconds"}
我做错了什么?
最佳答案
虽然run_slow_command
用coroutine
修饰,但它仍然处于阻塞状态,因此Tornado被阻塞并且无法运行任何代码,包括计时器,直到os.system
调用完成。您应该推迟对线程的调用:
from concurrent.futures import ThreadPoolExecutor
thread_pool = ThreadPoolExecutor(4)
@coroutine
def run_slow_command(command):
res = yield thread_pool.submit(os.system, command)
raise Return(res)
或者,由于您只想要 submit
返回的 Future,因此根本不要使用 coroutine
:
def run_slow_command(command):
return thread_pool.submit(os.system, command)
但是,您应该使用 Tornado 的 own Subprocess support,而不是使用 os.system
。总而言之,此示例等待子进程 5 秒,然后超时:
from datetime import timedelta
from functools import partial
from tornado import gen
from tornado.ioloop import IOLoop
from tornado.process import Subprocess
@gen.coroutine
def run_slow_command(command):
yield gen.with_timeout(
timedelta(seconds=5),
Subprocess(args=command.split()).wait_for_exit())
IOLoop.current().run_sync(partial(run_slow_command, 'sleep 10'))
关于python - Tornado with_timeout 正确用法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39251682/