New submission from Ilya Kulakov:
It looks like a signal delivered to multiprocessing's process implicitly
created by ProcessPoolExecutor triggers signal handler in the parent:
```
from concurrent.futures import ProcessPoolExecutor
import asyncio
import os
import signal
import sys
import time
def background_task():
print(f"Running background task {os.getpid()}", file=sys.stderr)
time.sleep(15)
print("Exiting background task", file=sys.stderr)
async def task():
print("Running task")
executor = ProcessPoolExecutor()
with executor:
loop = asyncio.get_event_loop()
try:
await loop.run_in_executor(executor, background_task)
except asyncio.CancelledError:
print("Cancelling task 1", file=sys.stderr)
try:
await asyncio.sleep(15)
except asyncio.CancelledError:
print("Cancelling task 2", file=sys.stderr)
raise
raise
def main():
def terminate(coro):
print(f"Terminating {os.getpid()}")
coro.cancel()
loop = asyncio.get_event_loop()
t = asyncio.ensure_future(task())
loop.add_signal_handler(signal.SIGTERM, terminate, t)
try:
print(f"Running {os.getpid()}", file=sys.stderr)
loop.run_until_complete(t)
finally:
loop.run_until_complete(loop.shutdown_asyncgens())
loop.close()
if __name__ == '__main__':
main()
```
1. Normal execution:
> Running 1000
> Running task
> Running background task 9999
> Exiting background task
2. Sending SIGTERM to parent once:
> Running 1000
> Running task
> Running background task 9999
< kill -s SIGTERM 9999
> Terminating 1000
> Cancelling task 1
> Exiting background task
3. Sending SIGTERM to parent twice:
> Running 1000
> Running task
> Running background task 9999
< kill -s SIGTERM 1000
> Terminating 1000
> Cancelling task 1
< kill -s SIGTERM 1000
> Terminating 1000
> Cancelling task 2
> Exiting background task
4. Sending SIGTERM to once to parent and once to child:
> Running 1000
> Running task
> Running background task 9999
< kill -s SIGTERM 1000
> Terminating 1000
> Cancelling task 1
< kill -s SIGTERM 9999
> Terminating 1000
> Cancelling task 2
> Exiting background task
As you can see, sending SIGTERM into a subprocess somehow triggered a signal
handler inside a parent. This is unexpected.
----------
components: asyncio
messages: 302321
nosy: Ilya.Kulakov, yselivanov
priority: normal
severity: normal
status: open
title: Signal delivered to a subprocess triggers parent's handler
type: behavior
versions: Python 3.6
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue31489>
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