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Copy pathtest_manager_fork_debug.py
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149 lines (123 loc) · 4.32 KB
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"""Minimal reproduction of multiprocessing Manager + fork failure."""
import multiprocessing
import os
import sys
import time
import traceback
import pytest
pytestmark = pytest.mark.skipif(not hasattr(os, "fork"), reason="requires os.fork")
def test_basic_manager():
"""Test Manager without fork - does it work at all?"""
print("=== Test 1: Basic Manager (no fork) ===")
ctx = multiprocessing.get_context("fork")
manager = ctx.Manager()
try:
ev = manager.Event()
print(f" Event created: {ev}")
ev.set()
print(f" Event set, is_set={ev.is_set()}")
assert ev.is_set()
print(" PASS")
finally:
manager.shutdown()
def test_manager_with_process():
"""Test Manager shared between parent and child process."""
print("\n=== Test 2: Manager with forked child ===")
ctx = multiprocessing.get_context("fork")
manager = ctx.Manager()
try:
result = manager.Value("i", 0)
ev = manager.Event()
def child_fn():
try:
ev.set()
result.value = 42
except Exception as e:
print(f" CHILD ERROR: {e}", file=sys.stderr)
traceback.print_exc()
sys.exit(1)
print(f" Starting child process...")
process = ctx.Process(target=child_fn)
process.start()
print(f" Waiting for child (pid={process.pid})...")
process.join(timeout=10)
if process.exitcode != 0:
print(f" FAIL: child exited with code {process.exitcode}")
return False
print(f" Child done. result={result.value}, event={ev.is_set()}")
assert result.value == 42
assert ev.is_set()
print(" PASS")
return True
finally:
manager.shutdown()
def test_manager_server_alive_after_fork():
"""Test that Manager server survives after forking a child."""
print("\n=== Test 3: Manager server alive after fork ===")
ctx = multiprocessing.get_context("fork")
manager = ctx.Manager()
try:
ev = manager.Event()
# Fork a child that does nothing with the manager
pid = os.fork()
if pid == 0:
# Child - exit immediately
os._exit(0)
# Parent - wait for child
os.waitpid(pid, 0)
# Now try to use the manager in the parent
print(f" After fork, trying to use Manager in parent...")
ev.set()
print(f" ev.is_set() = {ev.is_set()}")
assert ev.is_set()
print(" PASS")
return True
finally:
manager.shutdown()
def test_manager_server_alive_after_fork_with_child_usage():
"""Test that Manager server survives when child also uses it."""
print("\n=== Test 4: Manager server alive after fork + child usage ===")
ctx = multiprocessing.get_context("fork")
manager = ctx.Manager()
try:
child_ev = manager.Event()
parent_ev = manager.Event()
def child_fn():
try:
child_ev.set()
except Exception as e:
print(f" CHILD ERROR: {e}", file=sys.stderr)
traceback.print_exc()
sys.exit(1)
process = ctx.Process(target=child_fn)
process.start()
process.join(timeout=10)
if process.exitcode != 0:
print(f" FAIL: child exited with code {process.exitcode}")
return False
# Now use manager in parent AFTER child is done
print(f" Child done. Trying parent usage...")
parent_ev.set()
print(f" child_ev={child_ev.is_set()}, parent_ev={parent_ev.is_set()}")
assert child_ev.is_set()
assert parent_ev.is_set()
print(" PASS")
return True
finally:
manager.shutdown()
if __name__ == "__main__":
test_basic_manager()
passed = 0
total = 10
for i in range(total):
print(f"\n--- Iteration {i + 1}/{total} ---")
ok = True
ok = ok and test_manager_with_process()
ok = ok and test_manager_server_alive_after_fork()
ok = ok and test_manager_server_alive_after_fork_with_child_usage()
if ok:
passed += 1
else:
print(f" FAILED on iteration {i + 1}")
print(f"\n=== Results: {passed}/{total} passed ===")
sys.exit(0 if passed == total else 1)