Re: This operation would block forever

I found the solution here: 
http://uwsgi-docs.readthedocs.io/en/latest/Gevent.html

Regards,

Etienne


Le 2017-11-22 à 12:19, Etienne Robillard a écrit :
> Hi,
>
> My custom Schevo/ZODB backend uses gevent internally to make 
> asynchronous ZODB operations.
>
> Sometimes I get a internal 500 error/traceback:
>
> Traceback (most recent call last):
>   File "lib/notmm/controllers/wsgi.pyx", line 209, in 
> notmm.controllers.wsgi.BaseController.get_response 
> (lib/notmm/controllers/wsgi.c:4328)
>   File 
> "/home/erob/src/django-hotsauce/lib/notmm/dbapi/orm/decorators.py", 
> line 35, in _wrapper
>     return view_func(req, **kwargs)
>   File "/home/erob/src/blogengine2/lib/blogengine2/views/detail.py", 
> line 43, in details
>     result = db.Message.findone(messageid=oid)
>   File 
> "/home/erob/src/django-hotsauce/extras/libschevo/lib/schevo/extent.py", 
> line 174, in findone
>     results = self._find(self.name, criterion)
>   File 
> "/home/erob/src/django-hotsauce/extras/libschevo/lib/schevo/database2.py", 
> line 768, in _find_entity_oids
>     extent_name, criteria)
>   File 
> "/home/erob/src/django-hotsauce/extras/libschevo/lib/schevo/database2.py", 
> line 895, in _find_entity_oids_field_equality
>     results = list(branch.keys())
>   File "/home/erob/ncvs/ZODB/src/ZODB/Connection.py", line 783, in 
> setstate
>     p, serial = self._storage.load(oid)
>   File "/home/erob/ncvs/ZODB/src/ZODB/mvccadapter.py", line 144, in load
>     r = self._storage.loadBefore(oid, self._start)
>   File "/home/erob/work/ZEO-5.1.0/src/ZEO/ClientStorage.py", line 522, 
> in loadBefore
>     return self._server.load_before(oid, tid)
>   File "/home/erob/work/ZEO-5.1.0/src/ZEO/asyncio/client.py", line 
> 783, in load_before
>     return self.__call(self.client.load_before_threadsafe, oid, tid)
>   File "/home/erob/work/ZEO-5.1.0/src/ZEO/asyncio/client.py", line 
> 743, in call
>     return self.wait_for_result(result, timeout)
>   File "/home/erob/work/ZEO-5.1.0/src/ZEO/asyncio/client.py", line 
> 756, in wait_for_result
>     return future.result(timeout)
>   File 
> "/usr/local/lib/python2.7/dist-packages/futures-3.0.5-py2.7.egg/concurrent/futures/_base.py", 
> line 400, in result
>     self._condition.wait(timeout)
>   File "/usr/lib/python2.7/threading.py", line 340, in wait
>     waiter.acquire()
>   File "src/gevent/_semaphore.py", line 198, in 
> gevent._semaphore.Semaphore.acquire (src/gevent/gevent._semaphore.c:4541)
>   File "src/gevent/_semaphore.py", line 226, in 
> gevent._semaphore.Semaphore.acquire (src/gevent/gevent._semaphore.c:4367)
>   File "src/gevent/_semaphore.py", line 166, in 
> gevent._semaphore.Semaphore._do_wait 
> (src/gevent/gevent._semaphore.c:3562)
>   File "/usr/local/lib/python2.7/dist-packages/gevent/hub.py", line 
> 630, in switch
>     return RawGreenlet.switch(self)
> LoopExit: ('This operation would block forever', <Hub at 0xb370b93c 
> epoll pending=0 ref=0 fileno=12 
> resolver=<gevent.resolver_thread.Resolver at 0xb370e32c 
> pool=<ThreadPool at 0xb370e30c 0/1/10>> threadpool=<ThreadPool at 
> 0xb370e30c 0/1/10>>)
>
>  Any ideas what could be the cause of this blocking error when using 
> epoll and gevent to make ZODB operations under uWSGI and python 2.7?
>
> Regards,
>
> Etienne
>

-- 
Etienne Robillard
[email protected]
http://www.isotopesoftware.ca/

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