Issue 47195: importlib lock race issue in deadlock handling code (original) (raw)

We've seen tracebacks in production like:

File "", line 1004, in find_and_load(name='oe.gpg_sign', import=) File "", line 158, in _ModuleLockManager.enter() File "", line 110, in _ModuleLock.acquire() KeyError: 139622474778432

and

File "", line 1004, in find_and_load(name='oe.path', import=) File "", line 158, in _ModuleLockManager.enter() File "", line 110, in _ModuleLock.acquire() KeyError: 140438942700992

I've attached a reproduction script which shows that if an import XXX is in progress and waiting at the wrong point when an interrupt arrives (in this case a signal) and triggers it's own import YYY, _blocking_on[tid] in importlib/_bootstrap.py gets overwritten and lost, triggering the traceback we see above upon exit from the second import.

I'm using a signal handler here as the interrupt, I don't know what our production source is as yet but this reproducer proves it is possible.

This is a production backtrace after I inserted code to traceback if tid was already in _blocking_on. It is being triggered by a warning about an unclosed asyncio event loop and confirms my theory about nested imports, in the production case I'd guess being triggered by gc given the del.

File "/home/pokybuild/yocto-worker/oe-selftest-fedora/build/meta/classes/base.bbclass", line 26, in oe_import import oe.data File "", line 1024, in _find_and_load File "", line 171, in enter File "/home/pokybuild/yocto-worker/oe-selftest-fedora/build/bitbake/lib/bb/cooker.py", line 168, in acquire return orig_acquire(self) File "", line 110, in acquire File "/usr/lib64/python3.10/asyncio/base_events.py", line 685, in del _warn(f"unclosed event loop {self!r}", ResourceWarning, source=self) File "/usr/lib64/python3.10/warnings.py", line 112, in _showwarnmsg _showwarnmsg_impl(msg) File "/usr/lib64/python3.10/warnings.py", line 28, in _showwarnmsg_impl text = _formatwarnmsg(msg) File "/usr/lib64/python3.10/warnings.py", line 128, in _formatwarnmsg return _formatwarnmsg_impl(msg) File "/usr/lib64/python3.10/warnings.py", line 56, in _formatwarnmsg_impl import tracemalloc File "", line 1024, in _find_and_load File "", line 171, in enter File "/home/pokybuild/yocto-worker/oe-selftest-fedora/build/bitbake/lib/bb/cooker.py", line 167, in acquire bb.warn("\n".join(traceback.format_stack()))