Python interview questions and answers: Debugging and Profiling

Python: pdb debugger and cProfile profiler

Using Debugger:

• What is debugging in Python, and why is it important?

Explain the concept of debugging and its significance in identifying and fixing issues in Python code.

• What is pdb in Python? How is it used for debugging?

Describe pdb as the built-in Python debugger. Explain how it can be used to step through code, inspect variables, and identify bugs.

• How do you start the Python debugger (pdb) from the command line?

Explain the command or method to initiate the Python debugger (pdb) from the terminal or command prompt.

• What are breakpoints in debugging, and how do you set them using pdb in Python?

Define breakpoints and explain how you can set them at specific lines in the code using pdb.

• How do you execute the Python script with the debugger enabled?

Describe how to run a Python script with the debugger enabled so that it stops at the set breakpoints.

• What are the basic 'pdb' commands for debugging?

List and explain some common 'pdb' commands like n (next), s (step into), c (continue), p (print), q (quit), etc.

• How can you inspect variables' values during debugging using pdb in Python?

Explain the 'pdb' commands that allow you to inspect and display variable values at specific points in the code.

• What is conditional debugging, and how do you achieve it with pdb?

Describe how to set conditional breakpoints using 'pdb' to stop execution only when certain conditions are met.

• How do you handle exceptions while debugging with 'pdb'?

Explain the 'pdb' commands and techniques to handle exceptions during debugging and proceed with the debugging process.

• What is the difference between 'pdb.set_trace()' and breakpoint() in Python?

Explain the purpose of the 'pdb.set_trace()' and breakpoint() functions and their differences in Python versions.

• How do you exit the Python debugger (pdb) and resume normal script execution?

Describe the 'pdb' commands to exit the debugger and continue script execution.

cProfile:

• What is Python profiling, and why is it essential for performance optimization?

Discuss the concept of profiling in Python and how it can be used to identify performance bottlenecks.

• What types of Python profilers are available?

Describe the use cases of various Python profilers, such as cProfile, profile, and third-party profilers.

• What is cProfile in Python?

Describe how cProfile can be used to profile Python code.

• How do you use cProfile to profile a Python script?

Describe how to use cProfile to profile code and measure performance.

• What is the difference between the cProfile and profile modules in Python?

Compare the standard 'cProfile' module with the pure Python profile module.

• What kind of information does 'cProfile' provide about the code being profiled?

Give an explanation of the profiling data collected by 'cProfile', such as the number of calls, cumulative time, and time spent on each call.

• How can you sort and visualize 'cProfile' output to identify performance issues easily?

Explain how to analyze and interpret 'cProfile' output using sorting and visualization tools

• How do you profile specific functions or modules using cProfile?

Demonstrate how to profile particular functions or modules to narrow down performance analysis.

• What performance bottlenecks that cProfile can help identify in Python code?

Discuss typical issues like CPU-bound vs. I/O-bound tasks and potential optimizations revealed by 'cProfile'.

• How can you use cProfile to find memory usage and memory leaks in Python code?

Describe how 'cProfile' can be used to detect memory-related problems and optimize memory usage.