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pythontornadoyield

Python Tornado BadYieldError for POST request with timeout

I'm trying to write a post request for a Python Tornado server that sleeps for a second before sending a response back to a client. The server must handle many of these post requests per minute. The following code doesn't work because of BadYieldError: yielded unknown object <generator object get at 0x10d0b8870>

@asynchronous
def post(self):
    response = yield IOLoop.instance().add_timeout(time.time() + 1, self._process)
    self.write(response)
    self.finish()

@gen.coroutine
def _process(self, callback=None):
    callback("{}")

The server is to receive a post request, wait a second, and then return the result without blocking other requests. This is Python 2.7. How to resolve this? Thanks!

Solution

  • Either use callbacks or "yield", not both. So you could do:

    @asynchronous
def post(self):
    IOLoop.instance().add_timeout(time.time() + 1, self._process)

def _process(self):
    self.write("{}")
    self.finish()

    Or, better:

    @gen.coroutine
def post(self):
    yield gen.sleep(1)
    self.write("{}")
    # Tornado calls self.finish when coroutine exits.