Related
I am using Python 3.6.2, on Fedora 26 Workstation.
Below is some scrapbook code which demonstrates my issue:
EDIT: added Sam Hartman's suggestion to code.
import asyncio, json
from autobahn.asyncio.websocket import WebSocketClientProtocol, WebSocketClientFactory
class MyClientProtocol(WebSocketClientProtocol):
def onConnect(self, response):
print(response.peer)
def onOpen(self):
print("open")
self.sendMessage(json.dumps({'command': 'subscribe', 'channel': "1010"}).encode("utf8"))
def onMessage(self, payload, isBinary):
print("message")
print(json.loads(payload))
factory1 = WebSocketClientFactory("wss://api2.poloniex.com:443")
factory1.protocol = MyClientProtocol
loop1 = asyncio.get_event_loop()
loop1.run_until_complete(loop1.create_connection(factory1, "api2.poloniex.com", 443, ssl=True))
try:
loop1.run_forever()
except KeyboardInterrupt:
pass
loop1.close()
asyncio.set_event_loop(asyncio.new_event_loop())
factory2 = WebSocketClientFactory("wss://api2.poloniex.com:443")
factory2.protocol = MyClientProtocol
loop2 = asyncio.get_event_loop()
loop2.run_until_complete(loop2.create_connection(factory2, "api2.poloniex.com", 443, ssl=True))
try:
loop2.run_forever()
except KeyboardInterrupt:
pass
loop2.close()
After having closed an initial asyncio event loop, creating another and setting it as the global event loop, attempting to use the new event loop yields the following errors:
Fatal write error on socket transport
protocol: <asyncio.sslproto.SSLProtocol object at 0x7f8a84ed4748>
transport: <_SelectorSocketTransport fd=6>
Traceback (most recent call last):
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 762, in write
n = self._sock.send(data)
OSError: [Errno 9] Bad file descriptor
Fatal error on SSL transport
protocol: <asyncio.sslproto.SSLProtocol object at 0x7f8a84ed4748>
transport: <_SelectorSocketTransport closing fd=6>
Traceback (most recent call last):
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 762, in write
n = self._sock.send(data)
OSError: [Errno 9] Bad file descriptor
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/lib64/python3.6/asyncio/sslproto.py", line 648, in _process_write_backlog
self._transport.write(chunk)
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 766, in write
self._fatal_error(exc, 'Fatal write error on socket transport')
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 646, in _fatal_error
self._force_close(exc)
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 658, in _force_close
self._loop.call_soon(self._call_connection_lost, exc)
File "/usr/lib64/python3.6/asyncio/base_events.py", line 574, in call_soon
self._check_closed()
File "/usr/lib64/python3.6/asyncio/base_events.py", line 357, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
Exception in callback _SelectorSocketTransport._read_ready()
handle: <Handle _SelectorSocketTransport._read_ready()>
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/txaio/_common.py", line 63, in call_later
self._buckets[real_time][1].append(call)
KeyError: 412835000
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/lib64/python3.6/asyncio/events.py", line 127, in _run
self._callback(*self._args)
File "/usr/lib64/python3.6/asyncio/selector_events.py", line 731, in _read_ready
self._protocol.data_received(data)
File "/usr/lib64/python3.6/asyncio/sslproto.py", line 503, in data_received
ssldata, appdata = self._sslpipe.feed_ssldata(data)
File "/usr/lib64/python3.6/asyncio/sslproto.py", line 204, in feed_ssldata
self._handshake_cb(None)
File "/usr/lib64/python3.6/asyncio/sslproto.py", line 619, in _on_handshake_complete
self._app_protocol.connection_made(self._app_transport)
File "/usr/lib/python3.6/site-packages/autobahn/asyncio/websocket.py", line 97, in connection_made
self._connectionMade()
File "/usr/lib/python3.6/site-packages/autobahn/websocket/protocol.py", line 3340, in _connectionMade
WebSocketProtocol._connectionMade(self)
File "/usr/lib/python3.6/site-packages/autobahn/websocket/protocol.py", line 1055, in _connectionMade
self.onOpenHandshakeTimeout,
File "/usr/lib/python3.6/site-packages/txaio/_common.py", line 72, in call_later
self._notify_bucket, real_time,
File "/usr/lib/python3.6/site-packages/txaio/aio.py", line 382, in call_later
return self._config.loop.call_later(delay, real_call)
File "/usr/lib64/python3.6/asyncio/base_events.py", line 543, in call_later
timer = self.call_at(self.time() + delay, callback, *args)
File "/usr/lib64/python3.6/asyncio/base_events.py", line 553, in call_at
self._check_closed()
File "/usr/lib64/python3.6/asyncio/base_events.py", line 357, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
It seems reasonable that one might need to reopen an event loop after having closed an earlier one. Indeed this question even shows how: Asyncio Event Loop is Closed
The code below should achieve this:
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
so I am clearly doing something wrong. Can somebody see something missing?
I have fairly high confidence that your factory object is maintaining a reference to the old event loop presumably that it gets from asyncio.get_event_loop. Asyncio consumers are bad about getting hidden references to loops.
My recommendation is to reconstruct the web socket factory after closing the loop
So my twisted mail receiver is working nicely. Right up until we try to handle a case where the config is fubarred, and a mismatched cert/key is passed to the certificate options object for the factory.
I have a module, custom_esmtp.py, which includes an overload of ext_STARTLS(self,rest) which I have modified as follows, to include a try/except:
elif self.ctx and self.canStartTLS:
try:
self.sendCode(220, 'Begin TLS negotiation now')
self.transport.startTLS(self.ctx)
self.startedTLS = True
except:
log.err()
self.sendCode(550, "Internal server error")
return
When I run the code, having passed a cert and key that do not match, I get the following call stack:
Unhandled Error
Traceback (most recent call last):
File "/usr/local/lib/python2.7/site-packages/twisted/internet/tcp.py", line 220, in _dataReceived
rval = self.protocol.dataReceived(data)
File "/usr/local/lib/python2.7/site-packages/twisted/protocols/basic.py", line 454, in dataReceived
self.lineReceived(line)
File "/usr/local/lib/python2.7/site-packages/twisted/mail/smtp.py", line 568, in lineReceived
return getattr(self, 'state_' + self.mode)(line)
File "/usr/local/lib/python2.7/site-packages/twisted/mail/smtp.py", line 582, in state_COMMAND
method('')
--- <exception caught here> ---
File "custom_esmtp.py", line 286, in ext_STARTTLS
self.transport.startTLS(self.ctx)
File "/usr/local/lib/python2.7/site-packages/twisted/internet/_newtls.py", line 179, in startTLS
startTLS(self, ctx, normal, FileDescriptor)
File "/usr/local/lib/python2.7/site-packages/twisted/internet/_newtls.py", line 139, in startTLS
tlsFactory = TLSMemoryBIOFactory(contextFactory, client, None)
File "/usr/local/lib/python2.7/site-packages/twisted/protocols/tls.py", line 769, in __init__
contextFactory = _ContextFactoryToConnectionFactory(contextFactory)
File "/usr/local/lib/python2.7/site-packages/twisted/protocols/tls.py", line 648, in __init__
oldStyleContextFactory.getContext()
File "/usr/local/lib/python2.7/site-packages/twisted/internet/_sslverify.py", line 1429, in getContext
self._context = self._makeContext()
File "/usr/local/lib/python2.7/site-packages/twisted/internet/_sslverify.py", line 1439, in _makeContext
ctx.use_privatekey(self.privateKey)
OpenSSL.SSL.Error: [('x509 certificate routines', 'X509_check_private_key', 'key values mismatch')]
Line 286 of custom_esmtp.py is the self.transport.startTLS(self.ctx). I've looked through all the twisted modules listed in the stack, at the quoted lines, and there are no other try/except blocks.... So my understanding is that the error should be passed back up the stack, unhandled, until it reaches my handler in custom_esmtp.py? So why is it not getting handled - especially since the only except I have is a "catch all"?
Thanks in advance!
If you want this error to be caught, you can do:
from OpenSSL import SSL
# ...
try:
# ...
except SSL.Error:
# ...
Perhaps the syntax changes a bit. I can't check because I don't use this precise package, but the idea is that you have to declare the import path of the exceptions you want to catch.
I am seeing the python-requests library crash with the following traceback:
Traceback (most recent call last):
File "/usr/lib/python3.2/http/client.py", line 529, in _read_chunked
chunk_left = int(line, 16)
ValueError: invalid literal for int() with base 16: b''
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "./app.py", line 507, in getUrlContents
response = requests.get(url, headers=headers, auth=authCredentials, timeout=http_timeout_seconds)
File "/home/dotancohen/code/lib/requests/api.py", line 55, in get
return request('get', url, **kwargs)
File "/home/dotancohen/code/lib/requests/api.py", line 44, in request
return session.request(method=method, url=url, **kwargs)
File "/home/dotancohen/code/lib/requests/sessions.py", line 338, in request
resp = self.send(prep, **send_kwargs)
File "/home/dotancohen/code/lib/requests/sessions.py", line 441, in send
r = adapter.send(request, **kwargs)
File "/home/dotancohen/code/lib/requests/adapters.py", line 340, in send
r.content
File "/home/dotancohen/code/lib/requests/models.py", line 601, in content
self._content = bytes().join(self.iter_content(CONTENT_CHUNK_SIZE)) or bytes()
File "/home/dotancohen/code/lib/requests/models.py", line 542, in generate
for chunk in self.raw.stream(chunk_size, decode_content=True):
File "/home/dotancohen/code/lib/requests/packages/urllib3/response.py", line 222, in stream
data = self.read(amt=amt, decode_content=decode_content)
File "/home/dotancohen/code/lib/requests/packages/urllib3/response.py", line 173, in read
data = self._fp.read(amt)
File "/usr/lib/python3.2/http/client.py", line 489, in read
return self._read_chunked(amt)
File "/usr/lib/python3.2/http/client.py", line 534, in _read_chunked
raise IncompleteRead(b''.join(value))
http.client.IncompleteRead: IncompleteRead(0 bytes read)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/lib/python3.2/threading.py", line 740, in _bootstrap_inner
self.run()
File "./app.py", line 298, in run
self.target(*self.args)
File "./app.py", line 400, in provider_query
url_contents = getUrlContents(str(providerUrl), '', authCredentials)
File "./app.py", line 523, in getUrlContents
except http.client.IncompleteRead as error:
NameError: global name 'http' is not defined
As can be seen, I've tried to catch the http.client.IncompleteRead: IncompleteRead(0 bytes read) error that requests is throwing with the line except http.client.IncompleteRead as error:. However, that is throwing a NameError due to http not being defined. So how can I catch that exception?
This is the code throwing the exception:
import requests
from requests_oauthlib import OAuth1
authCredentials = OAuth1('x', 'x', 'x', 'x')
response = requests.get(url, auth=authCredentials, timeout=20)
Note that I am not including the http library, though requests is including it. The error is very intermittent (happens perhaps once every few hours, even if I run the requests.get() command every ten seconds) so I'm not sure if added the http library to the imports has helped or not.
In any case, in the general sense, if included library A in turn includes library B, is it impossible to catch exceptions from B without including B myself?
To answer your question
In any case, in the general sense, if included library A in turn includes library B, is it impossible to catch exceptions from B without including B myself?
Yes. For example:
a.py:
import b
# do some stuff with b
c.py:
import a
# but you want to use b
a.b # gives you full access to module b which was imported by a
Although this does the job, it doesn't look so pretty, especially with long package/module/class/function names in real world.
So in your case to handle http exception, either try to figure out which package/module within requests imports http and so that you'd do raise requests.XX.http.WhateverError or rather just import it as http is a standard library.
It's hard to analyze the problem if you don't give source and just the stout,
but check this link out : http://docs.python-requests.org/en/latest/user/quickstart/#errors-and-exceptions
Basically,
try and catch the exception whereever the error is rising in your code.
Exceptions:
In the event of a network problem (e.g. DNS failure, refused connection, etc),
Requests will raise a **ConnectionError** exception.
In the event of the rare invalid HTTP response,
Requests will raise an **HTTPError** exception.
If a request times out, a **Timeout** exception is raised.
If a request exceeds the configured number of maximum redirections,
a **TooManyRedirects** exception is raised.
All exceptions that Requests explicitly raises inherit
from **requests.exceptions.RequestException.**
Hope that helped.
I have a small script that repeatedly (hourly) fetches tweets from the API, using sixohsix's
Twitter Wrapper for Python. I am successful with handling most, if not all of the errors coming from the Twitter API, i.e. all the 5xx and 4xx stuff.
Nonetheless I randomly observe the below error traceback (only once in 2-3 days). I mean the program exits and the traceback is displayed in the shell. I have no clue what this could mean, but think it is not directly related to what my script does since it has proved itself to correctly run most of the time.
This is where I call a function of the wrapper in my script:
KW = {
'count': 200, # number of tweets to fetch (fetch maximum)
'user_id' : tweeter['user_id'],
'include_rts': 'false', # do not include native RT's
'trim_user' : 'true',
}
timeline = tw.twitter_request(tw_endpoint,\
tw_endpoint.statuses.user_timeline, KW)
The function tw.twitter_request(tw_endpoint, tw_endpoint.statuses.user_timeline, KW) basically does return tw_endpoint.statuses_user_timeline(**args), where args translate to KW, and tw_endpoint is an OAuthorized endpoint gained from using the sixohsix's library's
return twitter.Twitter(domain='api.twitter.com', api_version='1.1',
auth=twitter.oauth.OAuth(access_token, access_token_secret,
consumer_key, consumer_secret))
This is the traceback:
Traceback (most recent call last):
File "search_twitter_entities.py", line 166, in <module>
tw_endpoint.statuses.user_timeline, KW)
File "/home/tg/mild/twitter_utils.py", line 171, in twitter_request
return twitter_function(**args)
File "build/bdist.linux-x86_64/egg/twitter/api.py", line 173, in __call__
File "build/bdist.linux-x86_64/egg/twitter/api.py", line 177, in _handle_response
File "/usr/lib/python2.7/urllib2.py", line 126, in urlopen
return _opener.open(url, data, timeout)
File "/usr/lib/python2.7/urllib2.py", line 400, in open
response = self._open(req, data)
File "/usr/lib/python2.7/urllib2.py", line 418, in _open
'_open', req)
File "/usr/lib/python2.7/urllib2.py", line 378, in _call_chain
result = func(*args)
File "/usr/lib/python2.7/urllib2.py", line 1215, in https_open
return self.do_open(httplib.HTTPSConnection, req)
File "/usr/lib/python2.7/urllib2.py", line 1180, in do_open
r = h.getresponse(buffering=True)
File "/usr/lib/python2.7/httplib.py", line 1030, in getresponse
response.begin()
File "/usr/lib/python2.7/httplib.py", line 407, in begin
version, status, reason = self._read_status()
File "/usr/lib/python2.7/httplib.py", line 371, in _read_status
raise BadStatusLine(line)
httplib.BadStatusLine: ''
The only thing I can gain from that traceback is that the error happens somewhere deep inside another Python library and has something to do with an invalid HTTP stat coming from the Twitter API or the wrapper... But as I said, maybe some of you could give me a hint on how to debug/solve this since it is pretty annoying having to regularly check my script and restart it to continue fetching tweets.
EDIT: To clarify this a little, the first two functions in the traceback are already in a try-except block. For example, the try-except-Block in File "twitter_utils.py" filters out 40x and 50x exceptions, but also looks for general exceptions with only except:. So what I don't understand is why the error is not getting caught at this position and instead, the program is force-closed and a traceback printed? Shortly speaking I am in the situation where I cannot catch an error, just like a parse error in a PHP script. So how would I do this?
Perhaps this will point you in the right direction. This is what's being called when BadStatusLine is called upon:
class BadStatusLine(HTTPException):
def __init__(self, line):
if not line:
line = repr(line)
self.args = line,
self.line = line
I'm not too familiar with httplib, but if I had to guess, you're geting an empty response/error line and, well, it can't be parsed. There are comments before the line you're program is stopping at:
# Presumably, the server closed the connection before
# sending a valid response.
raise BadStatusLine(line)
If twitter is closing the connection before sending a response, you could try again, meaning do a try/except at "search_twitter_entities.py", line 166 a couple times (ugly).
try:
timeline = tw.twitter_request(tw_endpoint,\
tw_endpoint.statuses.user_timeline, KW)
except:
try:
timeline = tw.twitter_request(tw_endpoint,\
tw_endpoint.statuses.user_timeline, KW) # try again
except:
pass
Or, assuming you can reassign timeline as none each time, do a while loop:
timeline = None
while timeline == None:
try:
timeline = tw.twitter_request(tw_endpoint,\
tw_endpoint.statuses.user_timeline, KW)
except:
pass
I didn't test of of that. Check for bad code.
I build a short url translator engine in Python, and I'm seeing a TON of "broken pipe" errors, and I'm curious how to trap it best when using the BaseHTTPServer classes. This isn't the entire code, but gives you an idea of what I'm doing so far:
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
import memcache
class clientThread(BaseHTTPRequestHandler):
def do_GET(self):
content = None
http_code,response_txt,long_url = \
self.ag_trans_url(self.path,content,'GET')
self.http_output( http_code, response_txt, long_url )
return
def http_output(self,http_code,response_txt,long_url):
self.send_response(http_code)
self.send_header('Content-type','text/plain')
if long_url:
self.send_header('Location', long_url)
self.end_headers()
if response_txt:
self.wfile.write(response_txt)
return
def ag_trans_url(self, orig_short_url, post_action, getpost):
short_url = 'http://foo.co' + orig_short_url
# fetch it from memcache
long_url = mc.get(short_url)
# other magic happens to look it up from db if there was nothing
# in memcache, etc
return (302, None, log_url)
def populate_memcache()
# connect to db, do lots of mc.set() calls
def main():
populate_memcache()
try:
port = 8001
if len(sys.argv) > 1:
port = int(sys.argv[1])
server = HTTPServer(('',port), clientThread)
#server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
print '[',str(datetime.datetime.now()),'] short url processing has begun'
server.serve_forever()
except KeyboardInterrupt,SystemExit:
print '^C received, shutting down server'
server.socket.close()
The code itself works great, but started throwing errors almost immediately when in production:
Traceback (most recent call last):
File "/usr/lib/python2.5/SocketServer.py", line 222, in handle_request
self.process_request(request, client_address)
File "/usr/lib/python2.5/SocketServer.py", line 241, in process_request
self.finish_request(request, client_address)
File "/usr/lib/python2.5/SocketServer.py", line 254, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/usr/lib/python2.5/SocketServer.py", line 522, in __init__
self.handle()
File "/usr/lib/python2.5/BaseHTTPServer.py", line 316, in handle
self.handle_one_request()
File "/usr/lib/python2.5/BaseHTTPServer.py", line 310, in handle_one_request
method()
File "/opt/short_url_redirector/shorturl.py", line 38, in do_GET
self.http_output( http_code, response_txt, long_url )
File "/opt/short_url_redirector/shorturl.py", line 52, in http_output
self.send_response(http_code)
File "/usr/lib/python2.5/BaseHTTPServer.py", line 370, in send_response
self.send_header('Server', self.version_string())
File "/usr/lib/python2.5/BaseHTTPServer.py", line 376, in send_header
self.wfile.write("%s: %s\r\n" % (keyword, value))
File "/usr/lib/python2.5/socket.py", line 274, in write
self.flush()
File "/usr/lib/python2.5/socket.py", line 261, in flush
self._sock.sendall(buffer)
error: (32, 'Broken pipe')
The bulk of these errors seem to stem from having a problem calling the send_header() method where all I'm writing out is this:
self.send_header('Location', long_url)
So I'm curious where in my code to try to trap for this IO exception... do I write try/except calls around each of the self.send_header/self.end_headers/self.wfile.write calls? The other error I see from time to time is this one, but not sure which exception to watch to even catch this:
Traceback (most recent call last):
File "/usr/lib/python2.5/SocketServer.py", line 222, in handle_request
self.process_request(request, client_address)
File "/usr/lib/python2.5/SocketServer.py", line 241, in process_request
self.finish_request(request, client_address)
File "/usr/lib/python2.5/SocketServer.py", line 254, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/usr/lib/python2.5/SocketServer.py", line 522, in __init__
self.handle()
File "/usr/lib/python2.5/BaseHTTPServer.py", line 316, in handle
self.handle_one_request()
File "/usr/lib/python2.5/BaseHTTPServer.py", line 299, in handle_one_request
self.raw_requestline = self.rfile.readline()
File "/usr/lib/python2.5/socket.py", line 381, in readline
data = self._sock.recv(self._rbufsize)
error: (104, 'Connection reset by peer')
This appears to be a bug in SocketServer, see this link Python Bug: 14574
A fix (works for me in Python 2.7) is to override the SocketServer.StreamRequestHandler finish() method, something like this:
...
def finish(self,*args,**kw):
try:
if not self.wfile.closed:
self.wfile.flush()
self.wfile.close()
except socket.error:
pass
self.rfile.close()
#Don't call the base class finish() method as it does the above
#return SocketServer.StreamRequestHandler.finish(self)
The "broken pipe" exception means that your code tried to write to a socket/pipe which the other end has closed. If the other end is a web browser, the user could have stopped the request. You can ignore the traceback; it does not indicate a serious problem. If you want to suppress the message, you can put a try ... except block around all of the code in your http_output function, and log the exception if you like.
Additionally, if you want your HTTP server to process more than one request at a time, you need your server class to use one of the SocketServer.ForkingMixIn and SocketServer.ThreadingMixIn classes. Check the documentation of the SocketServer module for details.
Add: The "connection reset by peer" exception means that your code tried to read from a dead socket. If you want to suppress the traceback, you will need to extend the BaseHTTPServer class and override the handle_one_request method to add a try ... except block. You will need a new server class anyway, to implement the earlier suggestion about processing more than one request at a time.
In my application, the error didn't occur in finish(), it occurred in handle(). This fix catches the broken pipe errors:
class MyHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
...
def handle(self):
try:
BaseHTTPServer.BaseHTTPRequestHandler.handle(self)
except socket.error:
pass