Coverage after fork seems not to be generated #1941
Description
Describe the bug
If a python process uses os.fork it seems that even with concurreny=multiprocessing no coverage of the child process is generated. Example file below
To Reproduce
How can we reproduce the problem? Please be specific. Don't link to a failing CI job. Answer the questions below:
- What version of Python are you using?
3.11 - What version of coverage.py shows the problem? The output of
coverage debug sysis helpful.
7.6.12 - What code shows the problem?
This (not the nicest as it's just a quick hack to replicate some of our code)
#!/usr/bin/python3
import os
import tempfile
import time
import traceback
COMPLETE=tempfile.mkstemp()
print(f"Parent pid is {os.getpid()}")
pid = os.fork()
if pid:
print(f"In parent, child is {pid}")
try:
while True:
with open(COMPLETE[1], mode='r') as f:
data = f.readline()
print(f"Data is {data}")
if "Complete" in data:
print(f"Child is complete")
break
time.sleep(5)
finally:
wait_pid = 0
while wait_pid == 0:
wait_pid, rc = os.waitpid(pid, os.WNOHANG)
if wait_pid == 0:
time.sleep(2)
else:
print(f"In child")
time.sleep(10)
print("Leaving child")
with open(COMPLETE[1], mode='w') as f:
f.write("Complete")
os._exit(0)
Then run with coverage run -p --concurrency=multiprocessing test-fork-cover.py
Expected behavior
Expect to see coverage of both sides of the fork