我有一个小微网服务,它存储由id标识的本地消息。为了确保不会同时写入文件,我实现了一个队列。下面的代码只工作了一次,第二次上传的文件抛出了下面的回溯,我真的不知道如何正确处理fd。在
from tornado import web, ioloop, gen
from tornado.queues import Queue
from tornado.iostream import PipeIOStream
class Sample:
def __init__(self):
self.queue = Queue()
@gen.coroutine
def write_queue(self):
while True:
item = yield self.queue.get()
print("Message with id %s stored" % item[0])
fd = open(item[0], 'ab')
stream = PipeIOStream(fd.fileno())
yield stream.write(item[1])
stream.close_fd()
class MainHandler(web.RequestHandler):
def initialize(self, store):
self.store = store
@gen.coroutine
def put(self, id):
yield self.store.queue.put((id, self.request.body))
def start(store):
return web.Application([
(r"/(.*)", MainHandler,
{"store": store})
])
if __name__ == '__main__':
store = Store()
app = start(store)
app.listen(8888)
ioloop.IOLoop.current().add_callback(store.write_queue)
ioloop.IOLoop.current().start()
ERROR:tornado.application:Exception in callback functools.partial(<function wrap.<locals>.null_wrapper at 0x7f46657f46a8>, <Future finished exception=OSError(9, 'Bad file descriptor')>)
Traceback (most recent call last):
stream = PipeIOStream(fd.fileno())
File "/usr/local/lib/python3.5/dist-packages/tornado/iostream.py", line 1643, in __init__
self._fio = io.FileIO(self.fd, "r+")
OSError: [Errno 9] Bad file descriptor
open
返回的文件描述符不是管道。{em>在linux上通常不适用于的文件。这样的文件描述符总是被认为是可读的,从中读取或写入总是块。所以像这样使用PipeIOStream并不比简单地做fd.write(item[1])
好。您已经在只写模式下打开了文件,但是PipeIOStream将其文件包装在读/写包装器中(实际上,我有点惊讶于这种方式是否有效,因为真正的管道是单向的)。我认为这就是异常的来源。如果您以
'ab+'
模式打开文件,我想它会工作的。不过,我还没试过。相关问题 更多 >
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