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Set switch interval in a loop with increasing numbers #63

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Merged
ngoldbaum merged 1 commit into from
May 22, 2025
Merged

Set switch interval in a loop with increasing numbers #63

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11 changes: 10 additions & 1 deletion src/pytest_run_parallel/plugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -72,8 +72,17 @@ def inner(*args, **kwargs):
failed = None
barrier = threading.Barrier(n_workers)
original_switch = sys.getswitchinterval()
new_switch = 1e-6
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@ngoldbaum ngoldbaum May 22, 2025

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Suggested change
new_switch = 1e-6
new_switch = 1e-9

The PR description says nanoseconds

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@lysnikolaou lysnikolaou May 22, 2025

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Oh yeah, sorry. Meant microseconds instead. The plan was to start with the original value and increase by an order of magnitude if it fails.

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@ngoldbaum ngoldbaum May 22, 2025

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Just out of curiosity - when can this code get triggered? Or I guess said another way, when can sys.setswitchinterval fail? I've never had any issues setting the switch interval to a small number.

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@lysnikolaou lysnikolaou May 22, 2025

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My understanding is that on i386 and i586 (and especially the latter), there has always been some weird behavior around floats. This can lead to a rounding error, where the C implementation of sys.getswitchinterval effectively sees a 0 and raises a ValueError.

for _ in range(3):
try:
sys.setswitchinterval(new_switch)
break
except ValueError:
new_switch *= 10
else:
sys.setswitchinterval(original_switch)

try:
sys.setswitchinterval(0.000001)

def closure(*args, **kwargs):
for _ in range(n_iterations):
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