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PERF: Revert multiprocessing start method change introduced in Python 3.14 #1338

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Merged
kernc merged 1 commit into from
Dec 20, 2025
+9 −1
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PERF: Revert multiprocessing start method change introduced in Python 3.14 #1338

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5 changes: 5 additions & 0 deletions backtesting/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,12 +67,17 @@

from . import lib # noqa: F401
from ._plotting import set_bokeh_output # noqa: F401
from ._util import try_
from .backtesting import Backtest, Strategy # noqa: F401


# Add overridable backtesting.Pool used for parallel optimization
def Pool(processes=None, initializer=None, initargs=()):
import multiprocessing as mp
import sys
# Revert performance related change in Python>=3.14
if sys.platform.startswith('linux') and mp.get_start_method(allow_none=True) != 'fork':
try_(lambda: mp.set_start_method('fork'))
if mp.get_start_method() == 'spawn':
import warnings
warnings.warn(
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5 changes: 4 additions & 1 deletion backtesting/test/_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1039,10 +1039,13 @@ class TestDocs(TestCase):
DOCS_DIR = os.path.join(os.path.dirname(__file__), '..', '..', 'doc')

@unittest.skipUnless(os.path.isdir(DOCS_DIR), "docs dir doesn't exist")
@unittest.skipUnless(sys.platform.startswith('linux'), "test_examples requires mp.start_method=fork")
def test_examples(self):
import backtesting
examples = glob(os.path.join(self.DOCS_DIR, 'examples', '*.py'))
self.assertGreaterEqual(len(examples), 4)
with chdir(gettempdir()):
with chdir(gettempdir()), \
patch(backtesting, 'Pool', mp.get_context('fork').Pool):
for file in examples:
with self.subTest(example=os.path.basename(file)):
run_path(file)
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