I'm attempting to use the python Twitch-Python library for a simple Twitch bot to connect to chat and respond to messages. The bot works as expected, but about 1/6 times the bot fails to connect and the program simply ends. As explained on this error page, it seems to be because the thread ends and doesn't return anything at all https://github.com/PetterKraabol/Twitch-Python/issues/45
I have moved the Chat class into my own code, and have the following:
def __init__(self, channel: str, nickname: str, oauth: str, helix: Optional['twitch.Helix'] = None):
super().__init__()
self.helix: Optional['twitch.Helix'] = helix
self.irc = tc.IRC(nickname, password=oauth)
self.irc.incoming.subscribe(self._message_handler)
self.irc.start()
self.channel = channel.lstrip('#')
self.joined: bool = False
print(self.irc.is_alive())
The class is called with two different functions elsewhere, like so:
def handle_message(self, message : twitch.chat.Message) -> None:
print(message.sender, message.text)
def main(self):
ircConn = TCH(channel='#CHANNEL NAME", nickname="BOT NAME", oauth="SAMPLEOAUTH")
ircConn.subscribe(self.handle_message)
The issue is that about 1 in 6 times, the subscribe() doesn't actually do anything and the program ends. I'd like to find a way to detect when it fails, so that I may attempt a retry, but nothing I've found works. The function/class doesn't return anything, adding an on_error or on_completed argument to the subscribe() doesn't call anything, and using sys.excepthook also doesn't catch it failing.
Additionally, the IRC thread always prints True for irc.is_alive(), even when it fails afterwards.
How can I catch the thread failing? Thank you.
Related
I am coding a command (/mc, / is the prefix) for my discord bot to get and message a result. But getting the result takes a lot of time. To prevent multiple request at a time, I placed the code of getting the results in a separate function mainmc() (not async) and call mainmc as a thread by creating a new class mainThreadMC(threading.Thread) to start the thread, and create a new class object and start it, so that when there's multiple request the command will run instantly without having to wait for the previous one. But quickly after I run it, I've found out that it's not possible as sending a message needs await or else it won't work. But if you have await in a function the function needs async. That means I have to edit the module threading to make it work? And surely this is not the way to do it. But what should I do?
Here's the code (simplified):
class mainThreadMC(threading.Thread):
def __init__(self, threadID, name, ctx,args):
threading.Thread.__init__(self)
self.threadID = threadID
self.name = name
self.args = args
self.ctx = ctx
def run(self):
logger.info("Starting " + self.name)
mainmc(self.ctx,self.args)
logger.info(f'Exiting {self.name}')
def mainmc(ctx,args):
# fetching data... creating / editing variable embed
ctx.send(embed=embed) #ERROR!!!!!!!!!!!
# finalize...
return
#bot.command(name='mc',pass_content=True)
async def mc(ctx,*,args=""):
global runno
threadMainMC = mainThreadMC(runno,f"MainMC_{str(runno)}",ctx,args)
threadMainMC.start()
(I just want it to work, so if you have some alternative solutions you can also tell me.)
Thanks for helping.
I have a tornado webservice which is going to serve something around 500 requests per minute. All these requests are going to hit 1 specific endpoint. There is a C++ program that I have compiled using Cython and use it inside the tornado service as my processor engine. Each request that goes to /check/ will trigger a function call in the C++ program (I will call it handler) and the return value will get sent to user as response.
This is how I wrap the handler class. One important point is that I do not instantiate the handler in __init__. There is another route in my tornado code that I want to start loading the DataStructure after an authroized request hits that route. (e.g. /reload/)
executors = ThreadPoolExecutor(max_workers=4)
class CheckerInstance(object):
def __init__(self, *args, **kwargs):
self.handler = None
self.is_loading = False
self.is_live = False
def init(self):
if not self.handler:
self.handler = pDataStructureHandler()
self.handler.add_words_from_file(self.data_file_name)
self.end_loading()
self.go_live()
def renew(self):
self.handler = None
self.init()
class CheckHandler(tornado.web.RequestHandler):
async def get(self):
query = self.get_argument("q", None).encode('utf-8')
answer = query
if not checker_instance.is_live:
self.write(dict(answer=self.get_argument("q", None), confidence=100))
return
checker_response = await checker_instance.get_response(query)
answer = checker_response[0]
confidence = checker_response[1]
if self.request.connection.stream.closed():
return
self.write(dict(correct=answer, confidence=confidence, is_cache=is_cache))
def on_connection_close(self):
self.wait_future.cancel()
class InstanceReloadHandler(BasicAuthMixin, tornado.web.RequestHandler):
def prepare(self):
self.get_authenticated_user(check_credentials_func=credentials.get, realm='Protected')
def new_file_exists(self):
return True
def can_reload(self):
return not checker_instance.is_loading
def get(self):
error = False
message = None
if not self.can_reload():
error = True
message = 'another job is being processed!'
else:
if not self.new_file_exists():
error = True
message = 'no new file found!'
else:
checker_instance.go_fake()
checker_instance.start_loading()
tornado.ioloop.IOLoop.current().run_in_executor(executors, checker_instance.renew)
message = 'job started!'
if self.request.connection.stream.closed():
return
self.write(dict(
success=not error, message=message
))
def on_connection_close(self):
self.wait_future.cancel()
def main():
app = tornado.web.Application(
[
(r"/", MainHandler),
(r"/check", CheckHandler),
(r"/reload", InstanceReloadHandler),
(r"/health", HealthHandler),
(r"/log-event", SubmitLogHandler),
],
debug=options.debug,
)
checker_instance = CheckerInstance()
I want this service to keep responding after checker_instance.renew starts running in another thread. But this is not what happens. When I hit the /reload/ endpoint and renew function starts working, any request to /check/ halts and waits for the reloading process to finish and then it starts working again. When the DataStructure is being loaded, the service should be in fake mode and respond to people with the same query that they send as input.
I have tested this code in my development environment with an i5 CPU (4 CPU cores) and it works just fine! But in the production environment (3 double-thread CPU cores) the /check/ endpoint halts requests.
It is difficult to fully trace the events being handled because you have clipped out some of the code for brevity. For instance, I don't see a get_response implementation here so I don't know if it is awaiting something itself that could be dependent on the state of checker_instance.
One area I would explore is in the thread-safety (or seeming absence of) in passing the checker_instance.renew to run_in_executor. This feels questionable to me because you are mutating the state of a single instance of CheckerInstance from a separate thread. While it might not break things explicitly, it does seem like this could be introducing odd race conditions or unanticipated copies of memory that might explain the unexpected behavior you are experiencing
If possible, I would make whatever load behavior you have that you want to offload to a thread be completely self-contained and when the data is loaded, return it as the function result which can then be fed back into you checker_instance. If you were to do this with the code as-is, you would want to await the run_in_executor call for its result and then update the checker_instance. This would mean the reload GET request would wait until the data was loaded. Alternatively, in your reload GET request, you could ioloop.spawn_callback to a function that triggers the run_in_executor in this manner, allowing the reload request to complete instead of waiting.
I'm trying to create a Python-based CLI that communicates with a web service via websockets. One issue that I'm encountering is that requests made by the CLI to the web service intermittently fail to get processed. Looking at the logs from the web service, I can see that the problem is caused by the fact that frequently these requests are being made at the same time (or even after) the socket has closed:
2016-09-13 13:28:10,930 [22 ] INFO DeviceBridge - Device bridge has opened
2016-09-13 13:28:11,936 [21 ] DEBUG DeviceBridge - Device bridge has received message
2016-09-13 13:28:11,937 [21 ] DEBUG DeviceBridge - Device bridge has received valid message
2016-09-13 13:28:11,937 [21 ] WARN DeviceBridge - Unable to process request: {"value": false, "path": "testcube.pwms[0].enabled", "op": "replace"}
2016-09-13 13:28:11,936 [5 ] DEBUG DeviceBridge - Device bridge has closed
In my CLI I define a class CommunicationService that is responsible for handling all direct communication with the web service. Internally, it uses the websockets package to handle communication, which itself is built on top of asyncio.
CommunicationService contains the following method for sending requests:
def send_request(self, request: str) -> None:
logger.debug('Sending request: {}'.format(request))
asyncio.ensure_future(self._ws.send(request))
...where ws is a websocket opened earlier in another method:
self._ws = await websockets.connect(websocket_address)
What I want is to be able to await the future returned by asyncio.ensure_future and, if necessary, sleep for a short while after in order to give the web service time to process the request before the websocket is closed.
However, since send_request is a synchronous method, it can't simply await these futures. Making it asynchronous would be pointless as there would be nothing to await the coroutine object it returned. I also can't use loop.run_until_complete as the loop is already running by the time it is invoked.
I found someone describing a problem very similar to the one I have at mail.python.org. The solution that was posted in that thread was to make the function return the coroutine object in the case the loop was already running:
def aio_map(coro, iterable, loop=None):
if loop is None:
loop = asyncio.get_event_loop()
coroutines = map(coro, iterable)
coros = asyncio.gather(*coroutines, return_exceptions=True, loop=loop)
if loop.is_running():
return coros
else:
return loop.run_until_complete(coros)
This is not possible for me, as I'm working with PyRx (Python implementation of the reactive framework) and send_request is only called as a subscriber of an Rx observable, which means the return value gets discarded and is not available to my code:
class AnonymousObserver(ObserverBase):
...
def _on_next_core(self, value):
self._next(value)
On a side note, I'm not sure if this is some sort of problem with asyncio that's commonly come across or whether I'm just not getting it, but I'm finding it pretty frustrating to use. In C# (for instance), all I would need to do is probably something like the following:
void SendRequest(string request)
{
this.ws.Send(request).Wait();
// Task.Delay(500).Wait(); // Uncomment If necessary
}
Meanwhile, asyncio's version of "wait" unhelpfully just returns another coroutine that I'm forced to discard.
Update
I've found a way around this issue that seems to work. I have an asynchronous callback that gets executed after the command has executed and before the CLI terminates, so I just changed it from this...
async def after_command():
await comms.stop()
...to this:
async def after_command():
await asyncio.sleep(0.25) # Allow time for communication
await comms.stop()
I'd still be happy to receive any answers to this problem for future reference, though. I might not be able to rely on workarounds like this in other situations, and I still think it would be better practice to have the delay executed inside send_request so that clients of CommunicationService do not have to concern themselves with timing issues.
In regards to Vincent's question:
Does your loop run in a different thread, or is send_request called by some callback?
Everything runs in the same thread - it's called by a callback. What happens is that I define all my commands to use asynchronous callbacks, and when executed some of them will try to send a request to the web service. Since they're asynchronous, they don't do this until they're executed via a call to loop.run_until_complete at the top level of the CLI - which means the loop is running by the time they're mid-way through execution and making this request (via an indirect call to send_request).
Update 2
Here's a solution based on Vincent's proposal of adding a "done" callback.
A new boolean field _busy is added to CommunicationService to represent if comms activity is occurring or not.
CommunicationService.send_request is modified to set _busy true before sending the request, and then provides a callback to _ws.send to reset _busy once done:
def send_request(self, request: str) -> None:
logger.debug('Sending request: {}'.format(request))
def callback(_):
self._busy = False
self._busy = True
asyncio.ensure_future(self._ws.send(request)).add_done_callback(callback)
CommunicationService.stop is now implemented to wait for this flag to be set false before progressing:
async def stop(self) -> None:
"""
Terminate communications with TestCube Web Service.
"""
if self._listen_task is None or self._ws is None:
return
# Wait for comms activity to stop.
while self._busy:
await asyncio.sleep(0.1)
# Allow short delay after final request is processed.
await asyncio.sleep(0.1)
self._listen_task.cancel()
await asyncio.wait([self._listen_task, self._ws.close()])
self._listen_task = None
self._ws = None
logger.info('Terminated connection to TestCube Web Service')
This seems to work too, and at least this way all communication timing logic is encapsulated within the CommunicationService class as it should be.
Update 3
Nicer solution based on Vincent's proposal.
Instead of self._busy we have self._send_request_tasks = [].
New send_request implementation:
def send_request(self, request: str) -> None:
logger.debug('Sending request: {}'.format(request))
task = asyncio.ensure_future(self._ws.send(request))
self._send_request_tasks.append(task)
New stop implementation:
async def stop(self) -> None:
if self._listen_task is None or self._ws is None:
return
# Wait for comms activity to stop.
if self._send_request_tasks:
await asyncio.wait(self._send_request_tasks)
...
You could use a set of tasks:
self._send_request_tasks = set()
Schedule the tasks using ensure_future and clean up using add_done_callback:
def send_request(self, request: str) -> None:
task = asyncio.ensure_future(self._ws.send(request))
self._send_request_tasks.add(task)
task.add_done_callback(self._send_request_tasks.remove)
And wait for the set of tasks to complete:
async def stop(self):
if self._send_request_tasks:
await asyncio.wait(self._send_request_tasks)
Given that you're not inside an asynchronous function you can use the yield from keyword to effectively implement await yourself. The following code will block until the future returns:
def send_request(self, request: str) -> None:
logger.debug('Sending request: {}'.format(request))
future = asyncio.ensure_future(self._ws.send(request))
yield from future.__await__()
Related to this question I have the following code which subscribes to a redis pubsub queue and uses the handler provided in __init__ to feed the messages to the class that processes them:
from threading import Thread
import msgpack
class Subscriber(Thread):
def __init__(self, redis_connection, channel_name, handler):
super(Subscriber, self).__init__(name="Receiver")
self.connection = redis_connection
self.pubsub = self.connection.pubsub()
self.channel_name = channel_name
self.handler = handler
self.should_die = False
def start(self):
self.pubsub.subscribe(self.channel_name)
super(Subscriber, self).start()
def run(self):
for msg in self.pubsub.listen():
if self.should_die:
return
try:
data = msg["data"]
unpacked = msgpack.unpackb(data)
except TypeError:
# stop non-msgpacked, invalid, messages breaking stuff
# other validation happens in handler
continue
self.handler(unpacked)
def die(self):
self.should_die = True
In the linked question above, it is noted that pubsub.listen() never returns if the connection is dropped. Therefore, my die() function, while it can be called, will never actually cause the thread to terminate because it is hanging on the call to listen() inside the thread's run().
The accepted answer on the linked question mentions hacking redis-py's connection pool. I really don't want to do this and have a forked version of redis-py (at least until the fix is hopefully accepted into master), but I've had a look at the redis-py code anyway and don't immediately see where this change would be made.
Does anyone have an idea how to cleanly solve the hanging redis-py listen() call?
What issues will I incur by directly using Thread._Thread__stop?
To close this out after so many years. It ended up being a bug in the redis library. I debugged it and submitted the PR. It shouldn't occur any more.
I've made an IRC bot in Python and I've been trying to figure out a way to wait for an IRC command and return the message to a calling function for a while now. I refuse to use an external library for various reasons including I'm trying to learn to make these things from scratch. Also, I've been sifting through documentation for existing ones and they're way too comprehensive. I'me trying to make a simple one.
For example:
def who(bot, nick):
bot.send('WHO %s' % nick)
response = ResponseWaiter('352') # 352 - RPL_WHOREPLY
return response.msg
Would return a an object of my Message class that parses IRC messages to the calling function:
def check_host(bot, nick, host):
who_info = who(bot, nick)
if who_info.host == host:
return True
return False
I have looked at the reactor pattern, observer pattern, and have tried implementing a hundred different event system designs for this to no avail. I'm completely lost.
Please either provide a solution or point me in the right direction. There's got to be a simple way to do this.
So what I've done is use grab messages from my generator (a bot method) from the bot's who method. The generator looks like this:
def msg_generator(self):
''' Provides messages until bot dies '''
while self.alive:
for msg in self.irc.recv(self.buffer).split(('\r\n').encode()):
if len(msg) > 3:
try: yield Message(msg.decode())
except Exception as e:
self.log('%s %s\n' % (except_str, str(e)))
And now the bot's who method looks like this:
def who(self, nick):
self.send('WHO %s' % nick)
for msg in self.msg_generator():
if msg.command == '352':
return msg
However, it's now taking control of the messages, so I need some way of relinquishing the messages I'm not using for the who method to their appropriate handlers.
My bot generally handles all messages with this:
def handle(self):
for msg in self.msg_generator():
self.log('◀ %s' % (msg))
SpaghettiHandler(self, msg)
So any message that my SpaghettiHandler would be handling is not handled while the bot's who method uses the generator to receive messages.
It's working.. and works fast enough that it's hard to lose a message. But if my bot were to be taking many commands at the same time, this could become a problem. I'm pretty sure I'll find a solution in this direction, but I didn't create this as the answer because I'm not sure it's a good way, even when I have it set to relinquish messages that don't pertain to the listener.