Today we’re going to talk about a lesser-known but incredibly useful module in the Python standard library faulthandler. This bad boy is like your very own personal crash detective, helping you figure out what went wrong when things go south in your code. And let’s face it, that happens more often than we care to admit!

So how does this magical module work? Well, by default, Python writes tracebacks (the fancy term for error messages) to “sys.stderr”. But with faulthandler, you can enable a feature called “dumping” which saves the traceback to a log file instead of printing it to your terminal. This is especially useful if you’re running your code in a production environment where you don’t want those ***** error messages cluttering up your console.

faulthandler can also be used to dump tracebacks on a crash or when Python is deadlocked (which basically means it’s stuck and won’t do anything). This feature comes in handy if you want to debug issues that are causing your code to hang or freeze.

Now, let me give you an example of how to use faulthandler. First, make sure the module is installed by running “pip install python-faulthandler” (if it’s not already). Then, add this line at the beginning of your Python script:

# Import the faulthandler module
import faulthandler

# Enable the faulthandler to catch and display errors
faulthandler.enable()

# This line is used to install the faulthandler module if it's not already installed
# Use "pip install python-faulthandler" in the command line to install it
# This is necessary for the faulthandler module to work properly
# Make sure to run this command before running the script
# Otherwise, the script will not be able to use the faulthandler module

# This line enables the faulthandler to catch and display errors
# This is necessary for debugging issues that cause the code to hang or freeze
# Without this line, the script will not be able to catch and display errors
# This is the main purpose of using the faulthandler module in this script

This will enable dumping for all tracebacks in your code. If you want to specify a log file path instead of using “sys.stderr”, simply pass it as an argument like so:

# Import the faulthandler module
import faulthandler

# Enable the faulthandler to catch and display tracebacks
faulthandler.enable()

# Specify a log file path to save the tracebacks
# Use "sys.stderr" to print the tracebacks to the standard error stream
# Pass the log file path as an argument to the enable() function
faulthandler.enable(filename='my_log_file.txt')

And that’s it! Now, whenever a traceback occurs in your code, it will be saved to the specified log file instead of being printed to your console. Pretty cool, right?

faulthandler also has some advanced features like setting a maximum stack depth for dumping and disabling dumping altogether if you prefer. Check out the official documentation for all the juicy details.

However, we’d like to provide some additional context for this tutorial. In the Python Development Mode (PDM), faulthandler is automatically enabled at startup. This means that whenever an unhandled exception occurs in your code during development, PDM will save a dump of the traceback to a file named “faulthandler.txt” located in the current working directory.

This can be incredibly helpful for debugging purposes as it allows you to easily review and analyze the stack trace without having to manually enable faulthandler or modify your code. Additionally, PDM provides an interactive console that allows you to step through the execution of your code line by line, making it easier to identify the source of any issues.

To learn more about using Python Development Mode with faulthandler, check out their official documentation at https://docs.python.org/3/library/faulthandler.html and https://pypi.org/project/pdm/.