Debugging/sv

Prerequisites:

• software package gdb installed
• a debug build of FreeCAD (at this time only available by building from source)
• a FreeCAD model that causes a crash

Steps: Enter the following in your terminal window:

Find FreeCAD binary on your system:

$ whereis freecad
freecad: /usr/local/freecad <--- for example

$ cd /usr/local/freecad/bin
$ gdb FreeCAD

GNUdebugger will output some initializing information. The (gdb) shows GNUDebugger is running in the terminal, now input:

(gdb) handle SIG33 noprint nostop
(gdb) run

FreeCAD will now start up. Perform the steps that cause FreeCAD to crash or freeze, then enter in the terminal window:

(gdb) bt

This will generate a lengthy listing of exactly what the program was doing when it crashed or froze. Include this with your problem report.

(gdb) bt full

Print the values of the local variables also. This can be combined with a number to limit the number of frames shown.

Prerequisites:

• software package lldb installed
• a debug build of FreeCAD
• a FreeCAD model that causes a crash

Steps: Enter the following in your terminal window:

$ cd FreeCAD/bin
$ lldb FreeCAD

LLDB will output some initializing information. The (lldb) shows the debugger is running in the terminal, now input:

(lldb) run

FreeCAD will now start up. Perform the steps that cause FreeCAD to crash or freeze, then enter in the terminal window:

(lldb) bt

This will generate a lengthy listing of exactly what the program was doing when it crashed or froze. Include this with your problem report.

Here is an example of using Winpdb inside FreeCAD:

We need the Python debugger: Winpdb. If you do not have it installed, on Ubuntu/Debian install it with:

sudo apt-get install winpdb

Now lets setup the debugger.

1. Start Winpdb.
2. Set the debugger password to "test": Go to menu File → Password" and set the password.

Now we will run a test Python script in FreeCAD step by step.

1. Run winpdb and set the password (e.g. test)
2. Create a Python file with this content

import rpdb2
rpdb2.start_embedded_debugger("test")
import FreeCAD
import Part
import Draft
print "hello"
print "hello"
import Draft
points=[FreeCAD.Vector(-3.0,-1.0,0.0),FreeCAD.Vector(-2.0,0.0,0.0)]
Draft.makeWire(points,closed=False,face=False,support=None)

1. Start FreeCAD and load the above file into FreeCAD
2. Press F6 to execute it
3. Now FreeCAD will become unresponsive because the Python debugger is waiting
4. Switch to the Windpdb GUI and click on "Attach". After a few seconds an item "<Input>" appears where you have to double-click
5. Now the currently executed script appears in Winpdb.
6. Set a break at the last line and press F5
7. Now press F7 to step into the Python code of Draft.makeWire

Prerequisites:

• The ptvsd package needs to be installed in a Python 3 outside of FreeCAD, then the module must be copied to FreeCAD's Python library folder.

# In a cmd window that has a path to you local Python 3:
pip install ptvsd
# Then if your Python is installed in C:\Users\<userid>\AppData\Local\Programs\Python\Python37
# and your FreeCAD is installed in C:\freecad\bin
xcopy "C:\Users\<userid>\AppData\Local\Programs\Python\Python37\Lib\site-packages\ptvsd" "C:\freecad\bin\Lib\site-packages\ptvsd"

pypi page

Visual Studio Code documentation for remote debugging

Steps:

• Add following code at the beginning of your script

import ptvsd
print("Waiting for debugger attach")
# 5678 is the default attach port in the VS Code debug configurations
ptvsd.enable_attach(address=('localhost', 5678), redirect_output=True)
ptvsd.wait_for_attach()

• Add a debug configuration in Visual Studio Code Debug → Add Configurations….
• The config should look like this:

    "configurations": [
        {
            "name": "Python: Attacher",
            "type": "python",
            "request": "attach",
            "port": 5678,
            "host": "localhost",
            "pathMappings": [
                {
                    "localRoot": "${workspaceFolder}",
                    "remoteRoot": "."
                }
            ]
        },

• In VS Code add a breakpoint anywhere you want.
• Launch the script in FreeCAD. FreeCAD freeze waiting for attachment.
• In VS Code start debugging using created configuration. You should see variables in debugger area.
• When setting breakpoints, VS Code will complain about not finding the .py file opened in the VS Code editor.
  • Change "remoteRoot": "." to "remoteRoot": "<directory of file>"
    • For example, if the Python file resides in /home/FC_myscripts/myscript.py
    • Change to: "remoteRoot": "/home/FC_myscripts"
  • If you're just debugging FreeCAD macros from the FreeCAD macro folder, and that folder is "C:/Users/<userid>/AppData/Roaming/FreeCAD/Macro", then use:
    • "localRoot": "C:/Users/<userid>/AppData/Roaming/FreeCAD/Macro",
    • "remoteRoot": "C:/Users/<userid>/AppData/Roaming/FreeCAD/Macro"
• If your macro can't find ptvsd despite having installed it somewhere precede 'import ptvsd' with

from sys import path
sys.path.append('/path/to/site-packages')

Where the path is to the directory where ptvsd was installed.

• On the left bottom edge of VSCode you can choose the Python executable - it's best to make this the version packaged with FreeCAD.

In the Mac package it is /Applications/FreeCAD.App/Contents/Resources/bin/python.

You can locate it on your system by typing

import sys
print(sys.executable)

into FreeCAD's Python console.

• Extract AppImage.

> ./your location/FreeCAD_xxx.AppImage --appimage-extract
> cd squashfs-root/

• The sqashfs-root location is where the debugger later on is hooked up to.

• Make sure you can start a FreeCAD session from within the squashfs-root location.

squashfs-root> ./usr/bin/freecadcmd

• Should start up a FreeCAD commandline session.

• Install LiClipse.
  • Comes ready with pydev and has installers for all platforms.
  • For linux it is just to extract (to any location) and run.

• Configure liclipse for debugging.
  • Right-click pydev icon (upper right corner) and choose customize.
    • Activate "PyDev Debug" (through checkbox, or it might be needed to go to tab "Action Set Availability" and activate there first).
    • In the pydev menu you can now choose "start debug server".
  • Use menu window/open perspective/other > debug.
    • Right-click debug icon (upper right corner) and choose customize.
    • Checking "Debug" brings the debugging navigation tools to the toolbar.
  • Open preferences through menu window/preferences.
    • In PyDev/Interpreters add "new Interpreter by browsing".
    • The added interpreter should be: your loc/squashfs-root/usr/bin/python.
    • If you are only using this for fc, you can add AddOn workbench folders as well, or do that in a pydev-project later on.

• Find path to pydevd.py in your liclipse installation.
  • Something along the lines of: your location/liclipse/plugins/org.python.pydev.xx/pysrc.
• Create a regular pydev-project in liclipse.
  • Import external sources, for example a macro that you want to debug, or an external workbench.
  • In that macro (or workbench .py file) add the code lines:

import sys; sys.path.append("path ending with /pysrc")
import pydevd; pydevd.settrace()

• This is where the execution will halt when the macro is run.

• Start the liclipse debug server (menu pydev).

• Start FreeCAD.

squashfs-root> ./usr/bin/freecad

• Run the macro (or any other file with a pydevd.settrace() trigger) from within freecad, as you would normally do.

• Happy debugging.

• The use of LiClipse for remote debugging, and the steps described here related to liclipse, should work on any platform. The parts related to AppImage is for linux only.