Memory, Copies and Slow Code

Your learning sequence

1. 1 When Two Names Share One Object Read
2. 2 Not solved yet.○ Fix a Function That Changes Its Caller's List Practice · Easy
3. 3 When to Use is and When to Use == Read
4. 4 Not solved yet.○ Fix a Version Class That Compares Strings with is Practice · Easy
5. 5 Intern Repeated Strings, but Compare Them with == Read
6. 6 Copy Nested Data with deepcopy Read
7. 7 Not solved yet.○ Deep-Copy Only the Sections You Choose Practice · Medium
8. 8 What Keeps an Object Alive Read
9. 9 Not solved yet.○ Write a Context Manager Class Practice · Easy
10. 10 Handle Errors and Nesting in a Context Manager Read
11. 11 Not solved yet.○ Fix a Nested Context Manager That Hides Errors Practice · Medium
12. 12 How the Garbage Collector Finds Cycles Read
13. 13 Not solved yet.○ Walk an Object Graph with gc.get_referents and a Stack Practice · Medium
14. 14 Track Objects with Weak References Read
15. 15 Not solved yet.○ Build a Registry That Does Not Keep Objects Alive Practice · Medium
16. 16 What sys.getsizeof Measures Read
17. 17 Not solved yet.○ Add Up Nested Sizes, Counting Each Object Once Practice · Medium
18. 18 Find Memory Growth with tracemalloc Read
19. 19 Not solved yet.○ Measure Memory Growth and Always Stop Tracing Practice · Medium
20. 20 Measure What slots=True Saves Read
21. 21 Use a Set for Lookups and a Deque for Queues Read
22. 22 Not solved yet.○ Remove Duplicates in Order and Keep the Latest Items Practice · Easy
23. 23 Build Strings with join and Bytes with bytearray Read
24. 24 Not solved yet.○ Build a Report as Text and UTF-8 Bytes Practice · Medium
25. 25 Not solved yet.○ Fix a Slow Join and a Wasteful Top-k Practice · Medium
26. 26 Time Your Code with perf_counter Read
27. 27 Time Small Pieces of Code with timeit Read
28. 28 Not solved yet.○ Compare Best Timings and Put the Garbage Collector Back Practice · Medium
29. 29 Find Slow Functions with cProfile Read
30. 30 Not solved yet.○ Rank Profiled Functions by Self Time or Cumulative Time Practice · Medium
31. 31 Fix the Algorithm Before You Reach for NumPy Read
32. 32 Not solved yet.○ Speed Up a Moving Average with Prefix Sums Practice · Medium
33. 33 Check the Exact Python Version When You Debug the Collector Read
34. 34 Keep Forked Workers Sharing Memory with gc.freeze Read
35. 35 Profile with py-spy, Memray, Scalene and line_profiler Read
36. 36 Sample a Running Program with Tachyon in Python 3.15 Read
37. 37 Check Whether Your Python Has a JIT, Then Measure Read
38. 38 When to Write a C or Rust Extension Read

def add(x, acc=[]):
    acc.append(x)
    return acc

print(add(1), add(2), add(3))