r2b3 Failure to import _rclpy on windows

Bug report

Required Info:

• Operating System:
  • Windows 10 (Fresh install on a VM)
• Installation type:
  • from archive http://ci.ros2.org/view/packaging/job/packaging_windows/728/artifact/ws/ros2-package-windows-AMD64.zip
• Version or commit hash:
  • def304b4270b6b935b7d6fbbf7671634c2532452
• DDS implementation:
  • Fast-RTPS
• Client library (if applicable):
  • rclpy

Steps to reproduce issue

Symptom is a lot of errors when using ros2 command. This is after call C:\dev\ros2\local_setup.bat

C:\Users\osrf>ros2 --help
Failed to load entry point 'start': DLL load failed: The specified module could not be found.
Failed to load entry point 'status': DLL load failed: The specified module could not be found.
Failed to load entry point 'stop': DLL load failed: The specified module could not be found.
Failed to load entry point 'list': DLL load failed: The specified module could not be found.
Failed to load entry point 'call': DLL load failed: The specified module could not be found.
Failed to load entry point 'list': DLL load failed: The specified module could not be found.
Failed to load entry point 'echo': DLL load failed: The specified module could not be found.
Failed to load entry point 'list': DLL load failed: The specified module could not be found.
Failed to load entry point 'pub': DLL load failed: The specified module could not be found.
usage: ros2 [-h] Call `ros2 <command> -h` for more detailed usage. ...

ros2 is an extensible command-line tool for ROS 2.

optional arguments:
  -h, --help            show this help message and exit

Commands:
  daemon    Various daemon related sub-commands
  msg       Various msg related sub-commands
  node      Various node related sub-commands
  pkg       Various package related sub-commands
  run       Run a package specific executable
  security  Various security related sub-commands
  service   Various service related sub-commands
  srv       Various srv related sub-commands
  topic     Various topic related sub-commands

  Call `ros2 <command> -h` for more detailed usage.

Trying to load one of the entry points shows a traceback when importing _rclpy

>>> from ros2cli.verb.daemon import start
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\dev\ros2\Lib\site-packages\ros2cli\verb\daemon\start.py", line 15, in <module>
    from ros2cli.node.daemon import is_daemon_running
  File "C:\dev\ros2\Lib\site-packages\ros2cli\node\daemon.py", line 22, in <module>
    import rclpy
  File "C:\dev\ros2\Lib\site-packages\rclpy\__init__.py", line 17, in <module>
    from rclpy.executors import SingleThreadedExecutor as _SingleThreadedExecutor
  File "C:\dev\ros2\Lib\site-packages\rclpy\executors.py", line 21, in <module>
    from rclpy.impl.implementation_singleton import rclpy_implementation as _rclpy
  File "C:\dev\ros2\Lib\site-packages\rclpy\impl\implementation_singleton.py", line 32, in <module>
    rclpy_implementation = importlib.import_module('._rclpy', package='rclpy')
  File "C:\Python36\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ImportError: DLL load failed: The specified module could not be found.

Trying to import rclpy shows a similar error

>>> import rclpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\dev\ros2\Lib\site-packages\rclpy\__init__.py", line 17, in <module>
    from rclpy.executors import SingleThreadedExecutor as _SingleThreadedExecutor
  File "C:\dev\ros2\Lib\site-packages\rclpy\executors.py", line 21, in <module>
    from rclpy.impl.implementation_singleton import rclpy_implementation as _rclpy
  File "C:\dev\ros2\Lib\site-packages\rclpy\impl\implementation_singleton.py", line 32, in <module>
    rclpy_implementation = importlib.import_module('._rclpy', package='rclpy')
  File "C:\Python36\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ImportError: DLL load failed: The specified module could not be found.

Expected behavior

I’d expect no ImportError to be raised.

Actual behavior

Import error is raised

Additional information

sys.path

>>> import sys
>>> sys.path
['', 'C:\\dev\\ros2\\Lib\\site-packages', 'C:\\Python36\\python36.zip', 'C:\\Python36\\DLLs', 'C:\\Python36\\lib', 'C:\\Python36', 'C:\\Python36\\lib\\site-packages']

Not sure if I should see _rclpy.dll or something like that, but I don’t. There is _rclpy.pyd, is that what is failing to be found?

C:\Users\osrf>dir C:\dev\ros2\Lib\site-packages\rclpy
 Volume in drive C has no label.
 Volume Serial Number is AA39-7FB6

 Directory of C:\dev\ros2\Lib\site-packages\rclpy

09/12/2017  09:38 AM    <DIR>          .
09/12/2017  09:38 AM    <DIR>          ..
09/12/2017  09:38 AM             3,527 callback_groups.py
09/12/2017  09:38 AM             3,126 client.py
09/12/2017  09:38 AM               646 constants.py
09/12/2017  09:38 AM             2,558 exceptions.py
09/12/2017  09:38 AM            16,545 executors.py
09/12/2017  09:38 AM             1,505 expand_topic_name.py
09/12/2017  09:38 AM    <DIR>          impl
09/12/2017  09:38 AM             2,535 logging.py
09/12/2017  09:38 AM            12,211 node.py
09/12/2017  09:38 AM             1,087 publisher.py
09/12/2017  09:38 AM             5,581 qos.py
09/12/2017  09:38 AM             1,449 service.py
09/12/2017  09:38 AM             1,270 subscription.py
09/12/2017  09:38 AM             2,157 timer.py
09/12/2017  09:38 AM             1,210 topic_or_service_is_hidden.py
09/12/2017  09:38 AM             1,203 utilities.py
09/12/2017  09:38 AM             1,709 validate_full_topic_name.py
09/12/2017  09:38 AM             1,568 validate_namespace.py
09/12/2017  09:38 AM             1,378 validate_node_name.py
09/12/2017  09:38 AM             1,710 validate_topic_name.py
09/12/2017  09:38 AM             1,716 _rclpy.lib
09/12/2017  09:38 AM            44,032 _rclpy.pyd
09/12/2017  09:38 AM             1,932 _rclpy_logging.lib
09/12/2017  09:38 AM            11,264 _rclpy_logging.pyd
09/12/2017  09:38 AM             1,654 __init__.py
09/12/2017  09:46 AM    <DIR>          __pycache__
              24 File(s)        123,573 bytes
               4 Dir(s)   6,535,761,920 bytes free

[dirk-thomas]

I would keep the logic simple and point to a single page / ticket which than provides enough information to guide the user further.

[dirk-thomas]

It needs to be handled in rclpy wrapping the line you referenced.