Debugging GAE in Python Tools for Visual Studio

Question

I can run the appapp2 application for Google App Engine using Python Tools for Visual Studio 2012 without problems after the following this tutorial and even go through the server initialization code, but I can not get it to break when receiving or sending tags when the website loads, similarly what is shown in this video using the main() method. When I pause the debugger, it always ends in the following endless loop in the wsgi_server.py file:

 def _loop_forever(self): while True: self._select() def _select(self): with self._lock: fds = self._file_descriptors fd_to_callback = self._file_descriptor_to_callback if fds: if _HAS_POLL: # With 100 file descriptors, it is approximately 5x slower to # recreate and reinitialize the Poll object on every call to _select # rather reuse one. But the absolute cost of contruction, # initialization and calling poll(0) is ~25us so code simplicity # wins. poll = select.poll() for fd in fds: poll.register(fd, select.POLLIN) ready_file_descriptors = [fd for fd, _ in poll.poll(1)] else: ready_file_descriptors, _, _ = select.select(fds, [], [], 1) for fd in ready_file_descriptors: fd_to_callback[fd]() else: # select([], [], [], 1) is not supported on Windows. time.sleep(1) 

Is it possible to set breakpoints in the webapp2 application of the Google App Engine application in PTVS that start when the page loads from localhost?

Edit: using cprcrack settings, I was able to successfully launch GAE, but when I load the main page, I get an error

 Traceback (most recent call last): File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 3003, in _HandleRequest self._Dispatch(dispatcher, self.rfile, outfile, env_dict) File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 2862, in _Dispatch base_env_dict=env_dict) File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 719, in Dispatch base_env_dict=base_env_dict) File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 1797, in Dispatch self._module_dict) File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 1648, in ExecuteCGI app_log_handler = app_logging.AppLogsHandler() File "C:\Python\lib\logging\__init__.py", line 660, in __init__ _addHandlerRef(self) File "C:\Python\lib\logging\__init__.py", line 639, in _addHandlerRef _releaseLock() File "C:\Python\lib\logging\__init__.py", line 224, in _releaseLock _lock.release() File "C:\Python\lib\threading.py", line 138, in release self.__count = count = self.__count - 1 File "C:\Python\lib\threading.py", line 138, in release self.__count = count = self.__count - 1 File "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\Extensions\Microsoft\Python Tools for Visual Studio\2.0\visualstudio_py_debugger.py", line 557, in trace_func return self._events[event](frame, arg) File "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\Extensions\Microsoft\Python Tools for Visual Studio\2.0\visualstudio_py_debugger.py", line 650, in handle_line if filename == frame.f_code.co_filename or (not bound and filename_is_same(filename, frame.f_code.co_filename)): File "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\Extensions\Microsoft\Python Tools for Visual Studio\2.0\visualstudio_py_debugger.py", line 341, in filename_is_same import ntpath File "C:\Python\lib\ntpath.py", line 8, in <module> import os File "C:\Python\lib\os.py", line 120, in <module> from os.path import (curdir, pardir, sep, pathsep, defpath, extsep, altsep, ImportError: cannot import name curdir 

Did this error happen because I need to rollback to Python 2.5 to use the old dev_appserver?

Answer 1

UPDATE it looks like gcloud preview is now deprecated, it reverts to the old method

To make it work for gcloud preview (it is newer and simpler), replace this:

General-> Startup File:

 C:\Program Files\Google\Cloud SDK\google-cloud-sdk\lib\googlecloudsdk\gcloud\gcloud.py 

Debugging → Script Arguments:

 preview app run app.yaml --python-startup-script "pydevd_startup.py" --max-module-instances="default:1" 

the rest is the same as the original answer:

ORIGINAL RESPONSE:

It finally works for me: For formatted help see here , just copy and paste:

Create a file for entering a remote debugger

• create a new python file "pydevd_startup.py"

• insert this:

   import json import sys if ':' not in config.version_id: # The default server version_id does not contain ':' sys.path.append("lib") import ptvsd #ptvsd.settrace() equivalent ptvsd.enable_attach(secret = 'joshua') ptvsd.wait_for_attach() 

• Save it in your working directory of your application

• for more information see the pytool remote debugging document mentioned above.

Change project settings in VS 2013

Now open your project settings in VS and enter the following:

 General->Startup File: C:\Cloud SDK\google-cloud-sdk\bin\dev_appserver.py General->Working Directory: . Debug->Search Paths: C:\Cloud SDK\google-cloud-sdk\lib Debug->Script Arguments: --python_startup_script=".\pydevd_startup.py" --automatic_restart=no --max_module_instances="default:1" ".\app.yaml" 

Perhaps you can also use . instead of <path-to-your-app> , but I wanted to be safe.

Run debugger

With Ctrl + F5 you start the debugger without debugging. This sounds strange, but we are not actually debugging right now, we are just launching the dev server, which runs our script to enter the debugger code and wait for our remote debugger to be connected, which will happen in the next step

Launch Remote Debugger

 DEBUG->Attach to Process <Ctrl+Alt+P> Qualifier: tcp:// joshua@localhost :5678 <ENTER> 

joshua is your secret key. If you want to change it (and you should), you should also change it in pydevd_startup.py. See the pytool link for more information.

Answer 2

This is a known issue with the Google App Engine for Python: currently, debugging does not work on any debugger. See here, here and here .

Answer 3

There's a workaround there, but I don't know how this works for python tools for vs. In theory, this should be possible.

https://groups.google.com/forum/#!topicsearchin/google-appengine/Boa/google-appengine/-m00Qz4Vc7U

You will probably need this guide to get it working:

https://docs.google.com/document/d/1CCSaRiIWCLgbD3OwmuKsRoHHDfBffbROWyVWWL0ZXN4/edit#heading=h.fj44xnkhr0gr

Answer 4

I use the old dev_appserver for debugging, and it works for me in a script like yours. I also have a bunch of exceptions, but I was able to just skip them all by following the instructions in this link (I also had to add “exceptions” for some ValueError exceptions).

These are my project properties:

General Tab:

Boot file: C:\Program Files (x86)\Google\google_appengine\old_dev_appserver.py

Working Directory: ./

Windows application: (unverified)

Interpreter: Python 2.7

Debug Tab:

Search Paths: C:\Program Files (x86)\Google\google_appengine

Script Arguments: --use_sqlite ./

Interpreter arguments: (space)

Translator Path: C:\Python27\python.exe

When there is no need for breakpoints, I start the project using DEBUG> Execute Project in Python Interactive. This way you will not get an unnecessary console window.