Error:

File "/opt/mongodbtoolchain/v5/lib/python3.13/random.py", line 340, in randint
  return self.randrange(a, b+1)
         ~~~~~~~~~~~~~~^^^^^^^^
File "/opt/mongodbtoolchain/v5/lib/python3.13/random.py", line 316, in randrange
  istop = _index(stop)
TypeError: 'float' object cannot be interpreted as an integer

Description:

Python 3.13 removed support for passing float arguments to random.randint(), which was deprecated in Python 3.10.

The Problem in Our Code:

In config_fuzzer_limits.py, we have:

"replBatchLimitOperations": {
    "min": 1,
    "max": 0.2 * 1000 * 1000,  # Evaluates to float 200000.0, not int 200000
    ...
}

The arithmetic 0.2 * 1000 * 1000 produces a float type (200000.0) because one operand is a float. When this is passed to randint(), Python 3.13 rejects it.

Why It Worked in Python 3.10/3.11:

Python 3.10 and 3.11's randrange() implementation:

try:
    istart = _index(start)  # Strict integer check
except TypeError:
    istart = int(start)     # Fallback: convert float to int
    if istart != start:
        raise ValueError("non-integer arg")
    # Warn but continue (DeprecationWarning was hidden by default)

These versions would convert floats to integers and issue a DeprecationWarning (which was hidden by default, so developers didn't see it).

Why It Fails in Python 3.13:

Python 3.13's randrange() removed the fallback conversion:

istart = _index(start)  # Strict check only - raises TypeError for floats

The _index() function (operator.index()) only accepts true integer types and raises TypeError for floats, even floats with no fractional part like 200000.0.

References:

• Python 3.13 random.py randrange implementation
• Python 3.10 random.py randrange implementation