time.sleep 卡住了

Question

这是一个奇怪的问题，我只能在我们更强大的生产机器上重现这个问题。

def test_foo(self):
    res = self._run_job( ....)
    self.assertTrue("Hello Input!" in res.json()["stdout"], res.text)
    .........

def _run_job(self, cbid, auth, d):    
    .........
    while True:
        res = requests.get(URL+"/status/"+status_id, auth=auth)   <--- hangs here
        if res.json()["status"] != "Running":
            break
        else:
            time.sleep(2)
    ..........

我必须中断这个过程，这里是错误追踪信息：

Traceback (most recent call last):
  File "test_full.py", line 231, in <module>
    unittest.main()
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/main.py", line 98, in __init__
    self.runTests()
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/main.py", line 232, in runTests
    self.result = testRunner.run(self.test)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/runner.py", line 162, in run
    test(result)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/suite.py", line 64, in __call__
    return self.run(*args, **kwds)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/suite.py", line 84, in run
    self._wrapped_run(result)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/suite.py", line 114, in _wrapped_run
    test._wrapped_run(result, debug)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/suite.py", line 116, in _wrapped_run
    test(result)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/case.py", line 398, in __call__
    return self.run(*args, **kwds)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/unittest2/case.py", line 340, in run
    testMethod()
  File "test_full.py", line 59, in test_session
    "cmd": "python helloworld.py"
  File "test_full.py", line 129, in _run_job
    time.sleep(2)
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/gevent/hub.py", line 79, in sleep
    switch_result = get_hub().switch()
  File "/opt/graphyte/vens/gcs/local/lib/python2.7/site-packages/gevent/hub.py", line 164, in switch
    return greenlet.switch(self)
KeyboardInterrupt
Exception KeyError: KeyError(155453036,) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored

为什么会涉及到 gevent 呢？这是一个功能测试。它只是通过 requests 库发起 HTTP 请求，所以可能 switch 是指 requests。

但是作为一个简单的循环，怎么会出错呢？

Answer 1

为什么会涉及到 gevent 呢？

gevent 这个库会对一些标准模块进行“猴子补丁”，也就是对它们进行修改，让它们能够更好地合作工作。其中一个变化就是把 time.sleep 替换成 gevent.sleep。

http://www.gevent.org/gevent.monkey.html#gevent.monkey.patch_time

Answer 2

你在使用gevent的时候，有没有在做猴子补丁？

这可能是因为网络请求在进行中，但出于某种原因一直没有返回结果。我建议你暂时停止猴子补丁，直接在需要的地方使用gevent。

可能是因为现在请求是异步的，它会立即返回，然后再进行“睡眠”（也是异步的），接着再发请求，然后再重复这个过程……