Attempting to use gevent library in Python: “ImportError: cannot import name core”

Question

I'm attempting to use the gevent library in a Python app I'm writing. However, both easy_install and installing it manually appears to be failing. Any suggestions?

Python 2.6.2 (r262:71600, Aug  5 2009, 10:31:21) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gevent
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gevent/__init__.py", line 28, in <module>
    from gevent.greenlet import Greenlet, joinall, killall
  File "gevent/greenlet.py", line 5, in <module>
    from gevent import core
ImportError: cannot import name core
>>> 

The complete dump of my "build" and "install" commands are:

(env)[root@test1:downloads/gevent-0.10.0]# python setup.py build                                        (02-20 16:00)
found system libevent for linux2
running build
running build_py
creating build/lib.linux-i686-2.6
creating build/lib.linux-i686-2.6/gevent
copying gevent/rawgreenlet.py -> build/lib.linux-i686-2.6/gevent
copying gevent/thread.py -> build/lib.linux-i686-2.6/gevent
copying gevent/greenlet.py -> build/lib.linux-i686-2.6/gevent
copying gevent/event.py -> build/lib.linux-i686-2.6/gevent
copying gevent/hub.py -> build/lib.linux-i686-2.6/gevent
copying gevent/util.py -> build/lib.linux-i686-2.6/gevent
copying gevent/monkey.py -> build/lib.linux-i686-2.6/gevent
copying gevent/__init__.py -> build/lib.linux-i686-2.6/gevent
copying gevent/coros.py -> build/lib.linux-i686-2.6/gevent
copying gevent/select.py -> build/lib.linux-i686-2.6/gevent
copying gevent/wsgi.py -> build/lib.linux-i686-2.6/gevent
copying gevent/socket.py -> build/lib.linux-i686-2.6/gevent
copying gevent/queue.py -> build/lib.linux-i686-2.6/gevent
copying gevent/pool.py -> build/lib.linux-i686-2.6/gevent
copying gevent/timeout.py -> build/lib.linux-i686-2.6/gevent
copying gevent/backdoor.py -> build/lib.linux-i686-2.6/gevent
copying gevent/proc.py -> build/lib.linux-i686-2.6/gevent
running build_ext
building 'gevent.core' extension
creating build/temp.linux-i686-2.6
creating build/temp.linux-i686-2.6/gevent
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/usr/local/include/python2.6 -c gevent/core.c -o build/temp.linux-i686-2.6/gevent/core.o
gevent/core.c: In function ‘__pyx_pf_6gevent_4core_get_header_version’:
gevent/core.c:4360: warning: label ‘__pyx_L1_error’ defined but not used
gevent/core.c: In function ‘__pyx_pf_6gevent_4core_reinit’:
gevent/core.c:4419: warning: label ‘__pyx_L1_error’ defined but not used
gcc -pthread -shared build/temp.linux-i686-2.6/gevent/core.o -levent -o build/lib.linux-i686-2.6/gevent/core.so
(env)[root@test1:downloads/gevent-0.10.0]# python setup.py install                                      (02-20 16:01)
found system libevent for linux2
running install
running build
running build_py
running build_ext
running install_lib
creating /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/rawgreenlet.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/thread.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/greenlet.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/event.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/hub.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/util.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/monkey.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/__init__.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/coros.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/select.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/wsgi.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/socket.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/queue.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/pool.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/timeout.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/backdoor.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/proc.py -> /ews/test_project/env/lib/python2.6/site-packages/gevent
copying build/lib.linux-i686-2.6/gevent/core.so -> /ews/test_project/env/lib/python2.6/site-packages/gevent
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/rawgreenlet.py to rawgreenlet.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/thread.py to thread.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/greenlet.py to greenlet.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/event.py to event.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/hub.py to hub.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/util.py to util.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/monkey.py to monkey.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/__init__.py to __init__.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/coros.py to coros.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/select.py to select.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/wsgi.py to wsgi.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/socket.py to socket.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/queue.py to queue.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/pool.py to pool.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/timeout.py to timeout.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/backdoor.py to backdoor.pyc
byte-compiling /ews/test_project/env/lib/python2.6/site-packages/gevent/proc.py to proc.pyc
running install_egg_info
Writing /ews/test_project/env/lib/python2.6/site-packages/gevent-0.10.0-py2.6.egg-info
(env)[root@test1:downloads/gevent-0.10.0]# python                                                       (02-20 16:01)
Python 2.6.2 (r262:71600, Aug  5 2009, 10:31:21) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gevent
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gevent/__init__.py", line 28, in <module>
    from gevent.greenlet import Greenlet, joinall, killall
  File "gevent/greenlet.py", line 5, in <module>
    from gevent import core
ImportError: cannot import name core
>>> 

Answer 1

The error was caused simply by trying to run a script from the project source directory. Changing to any other directory and doing an "import" worked fine. More information here on the gevent mailing list.

Answer 2

I've answered your question on the mailing list.

BTW, are you using version 0.10.0 of gevent? It's ancient! The latest one is 0.12.0.