"Too hasty by far!", commit 21ce2ee4 attempted to avoid deprecated behavior altogether by calling new_event_loop() directly if there was no loop currently running, but this has the unfortunate side effect of potentially creating multiple event loops per thread if tests instantiate multiple QMP connections in a single thread. This behavior is apparently not well-defined and causes problems in some, but not all, combinations of Python interpreter version and platform environment.
Partially revert to Daniel Berrange's original patch, which calls get_event_loop and simply suppresses the deprecation warning in Python<=3.13. This time, however, additionally register new loops created with new_event_loop() so that future calls to get_event_loop() will return the loop already created. Signed-off-by: John Snow <[email protected]> cherry picked from commit c08fb82b38212956ccffc03fc6d015c3979f42fe Signed-off-by: John Snow <[email protected]> --- python/qemu/qmp/legacy.py | 21 +++++---------------- python/qemu/qmp/qmp_tui.py | 16 ++-------------- python/qemu/qmp/util.py | 27 +++++++++++++++++++++++++++ 3 files changed, 34 insertions(+), 30 deletions(-) diff --git a/python/qemu/qmp/legacy.py b/python/qemu/qmp/legacy.py index 775b1fdd3b3..e46695ae2c8 100644 --- a/python/qemu/qmp/legacy.py +++ b/python/qemu/qmp/legacy.py @@ -38,6 +38,7 @@ from .error import QMPError from .protocol import Runstate, SocketAddrT from .qmp_client import QMPClient +from .util import get_or_create_event_loop #: QMPMessage is an entire QMP message of any kind. @@ -86,19 +87,13 @@ def __init__(self, "server argument should be False when passing a socket") self._qmp = QMPClient(nickname) - self._created_loop = False - - try: - self._aloop = asyncio.get_running_loop() - except RuntimeError: - # No running loop; since this is a sync shim likely to be used - # in sync programs without any event loop at all, create one. - self._aloop = asyncio.new_event_loop() - self._created_loop = True - self._address = address self._timeout: Optional[float] = None + # This is a sync shim intended for use in fully synchronous + # programs. Create and set an event loop if necessary. + self._aloop = get_or_create_event_loop() + if server: assert not isinstance(self._address, socket.socket) self._sync(self._qmp.start_server(self._address)) @@ -331,12 +326,6 @@ def __del__(self) -> None: # user. self.close() - # If we created our own loop (and we are not running inside - # of it), we must close it to avoid warnings and error - # messages upon program exit. - if self._created_loop: - self._aloop.close() - if self._qmp.runstate != Runstate.IDLE: # If QMP is still not quiesced, it means that the garbage # collector ran from a context within the event loop and we diff --git a/python/qemu/qmp/qmp_tui.py b/python/qemu/qmp/qmp_tui.py index d5526338f22..d946c205131 100644 --- a/python/qemu/qmp/qmp_tui.py +++ b/python/qemu/qmp/qmp_tui.py @@ -51,7 +51,7 @@ from .message import DeserializationError, Message, UnexpectedTypeError from .protocol import ConnectError, Runstate from .qmp_client import ExecInterruptedError, QMPClient -from .util import pretty_traceback +from .util import get_or_create_event_loop, pretty_traceback # The name of the signal that is used to update the history list @@ -161,7 +161,6 @@ def __init__(self, address: Union[str, Tuple[str, int]], num_retries: int, self.retry_delay = retry_delay if retry_delay else 2 self.retry: bool = False self.exiting: bool = False - self._created_loop = False super().__init__() def add_to_history(self, msg: str, level: Optional[str] = None) -> None: @@ -388,14 +387,7 @@ def run(self, debug: bool = False) -> None: """ screen = urwid.raw_display.Screen() screen.set_terminal_properties(256) - - try: - self.aloop = asyncio.get_running_loop() - except RuntimeError: - # No running asyncio event loop. Create one. - self.aloop = asyncio.new_event_loop() - self._created_loop = True - + self.aloop = get_or_create_event_loop() self.aloop.set_debug(debug) # Gracefully handle SIGTERM and SIGINT signals @@ -418,10 +410,6 @@ def run(self, debug: bool = False) -> None: logging.error('%s\n%s\n', str(err), pretty_traceback()) raise err - def __del__(self) -> None: - if self._created_loop and self.aloop: - self.aloop.close() - class StatusBar(urwid.Text): """ diff --git a/python/qemu/qmp/util.py b/python/qemu/qmp/util.py index 0b3e781373d..47ec39a8b5e 100644 --- a/python/qemu/qmp/util.py +++ b/python/qemu/qmp/util.py @@ -10,6 +10,7 @@ import sys import traceback from typing import TypeVar, cast +import warnings T = TypeVar('T') @@ -20,6 +21,32 @@ # -------------------------- +def get_or_create_event_loop() -> asyncio.AbstractEventLoop: + """ + Return this thread's current event loop, or create a new one. + + This function behaves similarly to asyncio.get_event_loop() in + Python<=3.13, where if there is no event loop currently associated + with the current context, it will create and register one. It should + generally not be used in any asyncio-native applications. + """ + try: + with warnings.catch_warnings(): + # Python <= 3.13 will trigger deprecation warnings if no + # event loop is set, but will create and set a new loop. + warnings.simplefilter("ignore") + loop = asyncio.get_event_loop() + except RuntimeError: + # Python 3.14+: No event loop set for this thread, + # create and set one. + loop = asyncio.new_event_loop() + # Set this loop as the current thread's loop, to be returned + # by calls to get_event_loop() in the future. + asyncio.set_event_loop(loop) + + return loop + + async def flush(writer: asyncio.StreamWriter) -> None: """ Utility function to ensure a StreamWriter is *fully* drained. -- 2.50.1
