In-depth understanding of Python errors: Efficient troubleshooting with introspection and debugger
This article explores how to efficiently debug program errors using Python's introspection and debugging tools such as PDB. The article will be developed from the aspects of typical error information analysis, PDB debugger usage, production environment debugging, and frequently asked questions to help readers improve their Python debugging skills.
Python's powerful introspection allows us to understand runtime errors more deeply. By checking every frame in the call stack, including the calling parameters of the function, we can reproduce and understand errors more easily. Tools such as Sentry make full use of this feature to provide richer error context information.
Let's look at a common Python error example:
<code>TypeError: expected string or buffer File "sentry/stacktraces.py", line 309, in process_single_stacktrace processable_frame, processing_task) File "sentry/lang/native/plugin.py", line 196, in process_frame in_app = (in_app and not self.sym.is_internal_function(raw_frame.get('function'))) File "sentry/lang/native/symbolizer.py", line 278, in is_internal_function return _internal_function_re.search(function) is not None</code>
This error message only tells us the type and location of the error, but cannot directly point out the cause of the error. We may have to guess that integers or NoneTypes are passed, but the actual situation may be diverse.
Log record and PDB debugger
A simple debugging method is to add logging:
import logging # ... logging.debug("function is of type %s", type(function))
This helps to understand variable types during development. However, in production environments, this approach is not ideal due to the redundancy of DEBUG-level logs.
At this point, the Python debugger (PDB) comes in handy. PDB allows us to step through the code through breakpoints and check variables and their types. We can set breakpoints by inserting import pdb; pdb.set_trace()
into the code:
def is_internal_function(self, function): try: return _internal_function_re.search(function) is not None except Exception: import pdb; pdb.set_trace() raiseAfter the breakpoint hits, we will enter the PDB interactive environment where we can use the
to view the variable type, use the type(function)
to view local variables, and navigate the call stack with the locals()
and down
commands. up
Production environment debugging
In a production environment, the CPython runtime allows us to access the current call stack, including local variables for each execution frame.Exception information can be obtained, including traceback objects. By traversing the traceback object, we can access the sys.exc_info()
attribute of each frame to view the local variable: f_locals
exc_type, exc_value, tb = sys.exc_info() inner_frame = tb.tb_next.tb_frame # 可能需要遍歷tb_next找到合適的frame pprint(inner_frame.f_locals)Sentry will automatically perform similar introspection operations, providing rich error context information without manually adding code.
FAQ
The article finally provides FAQs about Python error debugging, covering common error types, PDB usage, IDE debugging, exception handling, remote debugging, multi-threaded debugging, third-party library debugging, performance problem debugging, and debugging skills improvement etc.
Some content of this article is adapted from Sentry articles. Thanks to our partners who support SitePoint.
The above is the detailed content of How to Debug Python Errors. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

In a world where online trust is non-negotiable, SSL certificates have become essential for every website. The market size of SSL certification was valued at USD 5.6 Billion in 2024 and is still growing strongly, fueled by surging e-commerce business

A payment gateway is a crucial component of the payment process, enabling businesses to accept payments online. It acts as a bridge between the customer and the merchant, securely transferring payment information and facilitating transactions. For

In what seems like yet another setback for a domain where we believed humans would always surpass machines, researchers now propose that AI comprehends emotions better than we do.Researchers have discovered that artificial intelligence demonstrates a

A new artificial intelligence (AI) model has demonstrated the ability to predict major weather events more quickly and with greater precision than several of the most widely used global forecasting systems.This model, named Aurora, has been trained u

Like it or not, artificial intelligence has become part of daily life. Many devices — including electric razors and toothbrushes — have become AI-powered," using machine learning algorithms to track how a person uses the device, how the devi

Artificial intelligence (AI) began as a quest to simulate the human brain.Is it now in the process of transforming the human brain's role in daily life?The Industrial Revolution reduced reliance on manual labor. As someone who researches the applicat

The more precisely we attempt to make AI models function, the greater their carbon emissions become — with certain prompts generating up to 50 times more carbon dioxide than others, according to a recent study.Reasoning models like Anthropic's Claude

Artificial intelligence (AI) models can threaten and blackmail humans when there’s a conflict between the model's objectives and user decisions, according to a new study.Published on 20 June, the research conducted by the AI firm Anthropic gave its l
