Narrowed down the issue. Basically, the grequests modules that I was using
seems to be the cause of the "LoopExit: This operation would block forever"
Create an application: *redis_event*
*controller: default.py*
import cache_mod
def index():
return dict(message=cache_mod.get_value())
*module: cache_mod.py*
import redis
import grequests
redis_cache = redis.StrictRedis(host='localhost', port=6379, db=0)
def get_value(key='SOME_KEY'):
return redis_cache.get(key)
view: index.html
<h2>{{=message}}</h2>
Once deployed on the server, access this url:
http://127.0.0.1:8000/redis_event/default/index
Reload the page successively - repeatedly F5 after page load - and you will
notice the error on the page.
Am moving away from grequests, and settling for just requests.
On Thursday, April 21, 2016 at 9:44:42 AM UTC+5:30, Kiran Subbaraman wrote:
>
> Thanks for the recommendation - IIS with web2py is a recommended
> deployment on Windows.
>
> The gevent-mix-up-with-rocket, was based on the stack trace I pasted
> below. And like I mentioned, this connection was made without any evidence
> ... so yeah, I was writing this before I gave it too much thought or
> investigation.
> In any case, I'll do some more investigation and try to track down this
> issue.
>
> ________________________________________
> Kiran Subbaramanhttp://subbaraman.wordpress.com/about/
>
> On Thu, 21-04-2016 3:42 AM, Niphlod wrote:
>
> forget about uwsgi on windows. never really landed as production-ready.
> fortunately iis can run python without any hiccup and it's the current
> recommended way to deploy web2py in production on windows.
>
> that being said, I'm really eager to know how the hell you're getting
> gevent mixed up with web2py's internal webserver, which is not at all
> compatible with gevent.
>
> On Wednesday, April 20, 2016 at 7:21:09 PM UTC+2, Kiran Subbaraman wrote:
>>
>> Hello all,
>> I use Windows 10 based laptop for my development. By default, web2py
>> serves its content via the rocket server.
>> My application makes use of the 'default' redis client () to connect to
>> the local redis server.
>> I started noticing a stacktrace, in the cmd prompt, from within which
>> web2py has started:
>> Created by Massimo Di Pierro, Copyright 2007-2016
>> Version 2.14.3-stable+timestamp.2016.03.26.17.54.43
>> Database drivers available: psycopg2, pymysql, imaplib, sqlite3, pg8000,
>> pyodbc, mysqlconnector
>> please visit:
>> http://127.0.0.1:8000/
>> starting browser...
>> please visit:
>> http://127.0.0.1:8000/
>> starting browser...
>> 2016-04-20 20:26:54,003 - Rocket.Errors.Port8000 - ERROR - Traceback (most
>> recent call last):
>> File "d:\code\git\web2py\gluon\rocket.py", line 587, in listen
>> sock, addr = self.listener.accept()
>> File "D:\programs\open\python27\lib\site-packages\gevent\socket.py",
>> line 316, in accept
>> self._wait(self._read_event)
>> File "D:\programs\open\python27\lib\site-packages\gevent\socket.py",
>> line 300, in _wait
>> self.hub.wait(watcher)
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 348, in wait
>> result = waiter.get()
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 575, in get
>> return self.hub.switch()
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 338, in switch
>> return greenlet.switch(self)
>> LoopExit: This operation would block forever
>>
>> The error in the error-ticket is:
>> <class 'gevent.hub.LoopExit'> This operation would block forever
>> Version
>> web2py™ Version 2.14.3-stable+timestamp.2016.03.26.17.54.43
>> Python Python 2.7.10: D:\programs\open\python27\python.exe (prefix:
>> D:\programs\open\python27)
>> Traceback
>>
>>
>> Traceback (most recent call last):
>> File "d:\code\git\web2py\gluon\restricted.py", line 227, in restricted
>> exec ccode in environment
>> File "d:/code/git/web2py/applications/myapp/controllers/myservice.py",
>> line 99, in <module>
>> File "d:\code\git\web2py\gluon\globals.py", line 417, in <lambda>
>> self._caller = lambda f: f()
>> File "d:\code\git\web2py\gluon\cache.py", line 661, in wrapped_f
>> rtn = func()
>> File "d:/code/git/web2py/applications/myapp/controllers/myservice.py",
>> line 68, in data
>> data = api.get_data(url)
>> File "applications\myapp\modules\data\api.py", line 145, in get_data
>> return _get_data_for(url) if url else None
>> File "applications\myapp\modules\data\api.py", line 164, in
>> _get_data_for
>> force_reload=rebuild
>> File "applications\myapp\modules\myapp_constants.py", line 460, in
>> get_from_cache
>> cache_value = redis_cache.get(key)
>> File "D:\programs\open\python27\lib\site-packages\redis\client.py",
>> line 880, in get
>> return self.execute_command('GET', name)
>> File "D:\programs\open\python27\lib\site-packages\redis\client.py",
>> line 573, in execute_command
>> return self.parse_response(connection, command_name, **options)
>> File "D:\programs\open\python27\lib\site-packages\redis\client.py",
>> line 585, in parse_response
>> response = connection.read_response()
>> File "D:\programs\open\python27\lib\site-packages\redis\connection.py",
>> line 577, in read_response
>> response = self._parser.read_response()
>> File "D:\programs\open\python27\lib\site-packages\redis\connection.py",
>> line 238, in read_response
>> response = self._buffer.readline()
>> File "D:\programs\open\python27\lib\site-packages\redis\connection.py",
>> line 168, in readline
>> self._read_from_socket()
>> File "D:\programs\open\python27\lib\site-packages\redis\connection.py",
>> line 126, in _read_from_socket
>> data = self._sock.recv(socket_read_size)
>> File "D:\programs\open\python27\lib\site-packages\gevent\socket.py",
>> line 394, in recv
>> self._wait(self._read_event)
>> File "D:\programs\open\python27\lib\site-packages\gevent\socket.py",
>> line 300, in _wait
>> self.hub.wait(watcher)
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 348, in wait
>> result = waiter.get()
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 575, in get
>> return self.hub.switch()
>> File "D:\programs\open\python27\lib\site-packages\gevent\hub.py", line
>> 338, in switch
>> return greenlet.switch(self)
>> LoopExit: This operation would block forever
>>
>> I do not see this issue on my ubuntu linux deployment.
>>
>> I suspected, without any evidence, that it may have to do with
>> process/threading between the rocket server to redis_client, and that it
>> could do with the monkey_patching of socket in the gevent world. Again, I
>> do not have any evidence, other than the stacktrace.
>>
>> The knee-jerk reaction was to see if using uwsgi or nginx on windows
>> alleviates this issue. The nearest discussion thread, that I came across,
>> that talks about setting up such an environment (web2py without rocket, but
>> uwsgi / nginx) is this one:
>> https://groups.google.com/forum/#!searchin/web2py/nginx$20windows/web2py/NdV0CVX8zZs/wWiRxogLz4sJ
>>
>> Any thoughts on what I could do or take a look at will help. Thanks.
>>
>> In the meantime, I also intend to
>>
>> - create a minimal app that is able to recreate this issue.
>> - take a look at the web2py's redis-cache.
>>
>> --
> Resources:
> - http://web2py.com
> - http://web2py.com/book (Documentation)
> - http://github.com/web2py/web2py (Source code)
> - https://code.google.com/p/web2py/issues/list (Report Issues)
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--
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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