Home | Forums | Couchbase | Couchbase Server 2.0

Python error

4 replies [Last post]
Wed, 12/12/2012 - 17:00
sctrbrain
Offline
Joined: 12/12/2012
Groups: None

When trying to set or get an object the operation itself seems to work (new documents appear in the DB on set at least) but I get the following exception printout every time:

< pre >
all_players_bucket.set(player['id'], 0, 0, json.dumps(player))
File "/Users/mbhamala/dev/feral/src/tanks/cage/eggs/couchbase-0.8.0-py2.7.egg/couchbase/client.py", line 222, in set
return self.mc_client.set(key, expiration, flags, value)
File "/Users/mbhamala/dev/feral/src/tanks/cage/eggs/couchbase-0.8.0-py2.7.egg/couchbase/couchbaseclient.py", line 556, in set
return self._respond(item, event)
File "/Users/mbhamala/dev/feral/src/tanks/cage/eggs/couchbase-0.8.0-py2.7.egg/couchbase/couchbaseclient.py", line 512, in _respond
raise item["response"]["error"]
error: cannot switch to a different thread
"

My server uses gevent and I'm wondering if this exception is related to gevent.

For this test case I create a new Couchbase client on every request with so there shouldn't be multiple greenlets using the same connection. 

    test_client = Couchbase('localhost:8091',
               username='Administrator',
               password='password')

Using Python couchbase 0.8.0 with requests 0.14.0

Anyone experienced anything similar?

Top
Thu, 12/13/2012 - 05:53
tgrall
Offline
Joined: 09/05/2012
Groups: None

Hello

This is the first time that I see this error. Could you please give us your environment information to help us reproduce the issue?
Couchbase Server, OS, ..., versions..

Thanks
Tug

__________________

Tug
@tgrall

Top
Thu, 12/13/2012 - 06:09
sctrbrain
Offline
Joined: 12/12/2012
Groups: None

- Mac OS X 10.7.4
- couchbase-server-community_x86_64_2.0.0
- requests 0.14.0
- python couchbase driver 0.8.0
- gevent 1.0rc1

I'm running a server built on gevent and if I had to guess I would say that either the streaming_thread or dispatcher_thread in couchbaseclient.py doesn't interact well with the gevent internals. I'm not very familiar with gevent and thread interoperability but my understanding is that mixing greenlets and threads may cause issues.

Mongo's python client pymongo has solved this by implementing gevent support into the driver: http://api.mongodb.org/python/current/examples/gevent.html

Top
Fri, 12/14/2012 - 02:06
conekia
Offline
Joined: 12/14/2012
Groups: None

Yes.

Make sure to put this at the begining of your code:

from gevent import monkey
monkey.patch_all()

We have couchbase-python 0.8.0 with last trunk of gevent working faultlessly

Top
Fri, 12/14/2012 - 03:15
sctrbrain
Offline
Joined: 12/12/2012
Groups: None

Awesome, thanks!

I had only monkey patched socket and missed patching all else.

Top