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gh-150429: Fix sampling profiler generator stack test #150433

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gh-150429: Fix sampling profiler generator stack test #150433

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71 changes: 45 additions & 26 deletions Lib/test/test_profiling/test_sampling_profiler/test_blocking.py
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Original file line number Diff line number Diff line change
Expand Up @@ -39,8 +39,9 @@ class TestBlockingModeStackAccuracy(unittest.TestCase):
@classmethod
def setUpClass(cls):
# Test script that uses a generator consumed in a loop.
# When consume_generator is on the arithmetic lines (temp1, temp2, etc.),
# fibonacci_generator should NOT be in the stack at all.
# When consume_generator is the executing leaf frame on the arithmetic
# lines (temp1, temp2, etc.), fibonacci_generator should NOT be in the
# stack at all.
# Line numbers are important here - see ARITHMETIC_LINES below.
cls.generator_script = textwrap.dedent('''
def fibonacci_generator(n):
Expand All @@ -65,29 +66,32 @@ def main():
main()
''')
# Line numbers of the arithmetic operations in consume_generator.
# These are the lines where fibonacci_generator should NOT be in the stack.
# The socket injection code adds 7 lines before our script.
# temp1 = value + 1 -> line 17
# temp2 = value * 2 -> line 18
# temp3 = value - 1 -> line 19
# result = ... -> line 20
cls.ARITHMETIC_LINES = {17, 18, 19, 20}
# These are the lines where fibonacci_generator should NOT be in the
# stack when consume_generator is the executing leaf frame. They account
# for the socket prelude added by test_subprocess().
# temp1 = value + 1 -> line 16
# temp2 = value * 2 -> line 17
# temp3 = value - 1 -> line 18
# result = ... -> line 19
cls.ARITHMETIC_LINES = {16, 17, 18, 19}

def test_generator_not_under_consumer_arithmetic(self):
"""Test that fibonacci_generator doesn't appear when consume_generator does arithmetic.

When consume_generator is executing arithmetic lines (temp1, temp2, etc.),
fibonacci_generator should NOT be anywhere in the stack - it's not being
called at that point.
When consume_generator is the leaf frame on arithmetic lines (temp1,
temp2, etc.), fibonacci_generator should NOT be anywhere in the stack -
it's not being called at that point. Non-leaf frame line numbers are
caller/resume metadata, not proof that the frame is executing.

Valid stacks:
- consume_generator at 'for value in gen:' line WITH fibonacci_generator
at the top (generator is yielding)
- fibonacci_generator at the top (generator is executing), with
consume_generator below it
- consume_generator at arithmetic lines WITHOUT fibonacci_generator
(we're just doing math, not calling the generator)

Invalid stacks (indicate torn/inconsistent reads):
- consume_generator at arithmetic lines WITH fibonacci_generator
- consume_generator leaf frame at arithmetic lines WITH
fibonacci_generator
anywhere in the stack

Note: call_tree is ordered from bottom (index 0) to top (index -1).
Expand All @@ -110,22 +114,30 @@ def test_generator_not_under_consumer_arithmetic(self):
total_samples = 0
invalid_stacks = 0
arithmetic_samples = 0
generator_samples = 0
generator_not_leaf_samples = 0

for (call_tree, _thread_id), count in collector.stack_counter.items():
total_samples += count

if not call_tree:
continue

# Find consume_generator in the stack and check its line number
for i, (filename, lineno, funcname) in enumerate(call_tree):
if funcname == "consume_generator" and lineno in self.ARITHMETIC_LINES:
arithmetic_samples += count
# Check if fibonacci_generator appears anywhere in this stack
func_names = [frame[2] for frame in call_tree]
if "fibonacci_generator" in func_names:
invalid_stacks += count
break
# Non-leaf frame line numbers can point at resume locations while
# a callee is the executing leaf frame.
_, lineno, funcname = call_tree[-1]
func_names = [frame[2] for frame in call_tree]

if "fibonacci_generator" in func_names:
generator_samples += count
if funcname != "fibonacci_generator":
generator_not_leaf_samples += count

if funcname == "consume_generator" and lineno in self.ARITHMETIC_LINES:
arithmetic_samples += count
# Check if fibonacci_generator appears anywhere in this stack.
if "fibonacci_generator" in func_names:
invalid_stacks += count

self.assertGreater(total_samples, 10,
f"Expected at least 10 samples, got {total_samples}")
Expand All @@ -134,8 +146,15 @@ def test_generator_not_under_consumer_arithmetic(self):
self.assertGreater(arithmetic_samples, 0,
f"Expected some samples on arithmetic lines, got {arithmetic_samples}")

self.assertGreater(generator_samples, 0,
f"Expected some samples in fibonacci_generator, got {generator_samples}")

self.assertEqual(generator_not_leaf_samples, 0,
f"Found {generator_not_leaf_samples}/{generator_samples} stacks where "
f"fibonacci_generator appears but is not the leaf frame.")

self.assertEqual(invalid_stacks, 0,
f"Found {invalid_stacks}/{arithmetic_samples} invalid stacks where "
f"fibonacci_generator appears in the stack when consume_generator "
f"is on an arithmetic line. This indicates torn/inconsistent stack "
f"traces are being captured.")
f"is the leaf frame on an arithmetic line. This indicates "
f"torn/inconsistent stack traces are being captured.")
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