POC Troubleshooting & Problem Resolution 5

Question 1

A `StopIteration` exception propagates out of a generator function unexpectedly. What Python version behavior causes this?

Accepted Answer

In Python 3.7+, StopIteration raised inside a generator is converted to RuntimeError

Answer

Generators no longer support StopIteration in Python 3

Answer

StopIteration can only be raised by iterators, not generators

Answer

The return value of a generator must be None

Question 2

You profile a slow script with `cProfile` and find most time is spent in a pure-Python loop. What is the best optimization?

Accepted Answer

Replace the loop with a NumPy vectorized operation or a built-in written in C

Answer

Add more comments to the loop for clarity

Answer

Increase the Python recursion limit

Answer

Split the loop across multiple files

Question 3

You get `ssl.SSLCertVerificationError` when making an HTTPS request. What is the secure resolution?

Accepted Answer

Update the CA certificates bundle used by Python or the requests library

Answer

Pass verify=False to disable certificate verification

Answer

Switch from HTTPS to HTTP

Answer

Use a self-signed certificate

Question 4

A long-running script leaks memory over time. `tracemalloc` shows many small string allocations in a loop. What is a likely culprit?

Accepted Answer

String concatenation with `+` inside a loop, creating a new object each iteration

Answer

Using f-strings instead of % formatting

Answer

Importing the `sys` module inside the loop

Answer

Reading a file in text mode instead of binary mode

Question 5

A subprocess call with `subprocess.run(['ls', '-l'])` works locally but raises `FileNotFoundError` on Windows. Why?

Accepted Answer

`ls` is a Unix command not available on Windows; use `dir` with `shell=True` on Windows

Answer

subprocess.run is not supported on Windows

Answer

The `-l` flag is not recognized by subprocess

Answer

The list form of arguments only works on Linux

Question 6

You add `print` statements to debug, but output is not visible when piping the script's stdout. What causes this?

Accepted Answer

Python buffers stdout when writing to a pipe; use flush=True or set PYTHONUNBUFFERED=1

Answer

print() is disabled when stdout is redirected

Answer

Piping replaces stdout with stderr

Answer

The pipe requires the script to use sys.stdout.write()

Question 7

A class method decorated with `@staticmethod` raises `TypeError: method() takes 0 positional arguments but 1 was given`. What went wrong?

Accepted Answer

The decorator was removed or misapplied, so Python is passing `self` to what should be a static method

Answer

Static methods cannot be called on instances

Answer

The method has a default argument conflict

Answer

You must use `cls` instead of no argument in static methods