When unplugging a monitor there is a careful synchronization dance between the monitor handling the "object-del" command and the command processing for the monitor being deleted. The stress test runs a busy loop of 'query-qmp-schema' on a second monitor, while the primary monitor requests its deletion. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Tested-by: Peter Krempa <pkrempa@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- .../generic/test_monitor_hotplug.py | 62 +++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/tests/functional/generic/test_monitor_hotplug.py b/tests/functional/generic/test_monitor_hotplug.py index 5d8a159eb0..55af8a238f 100755 --- a/tests/functional/generic/test_monitor_hotplug.py +++ b/tests/functional/generic/test_monitor_hotplug.py @@ -6,11 +6,16 @@ # # Copyright (c) 2026 Christian Brauner +import asyncio import os +import random +import threading +import time from qemu_test import QemuSystemTest from qemu.qmp.legacy import QEMUMonitorProtocol +from qemu.qmp import QMPClient class MonitorHotplug(QemuSystemTest): @@ -163,6 +168,63 @@ def test_events_after_negotiation(self): qmp.close() self._remove_monitor() + def stress_mon(self, sock): + async def main(): + qmp = QMPClient('testvm') + await qmp.connect(sock) + # Run query-version in a tight loop so that the + # monitor thread/dispatcher is very busy at the + # time we try to delete the monitor + while True: + try: + # A command which returns a lot of data to make + # it more likely we're in the I/O reply path + # when deleting the monitor + res = await qmp.execute('query-qmp-schema') + # Some commands which generate async events + # as those can trigger different code paths + res = await qmp.execute('stop') + res = await qmp.execute('cont') + except: + # we'll get here if the monitor is terminated + # by QEMU in which case we must disconnect + # out side, but.... + try: + await qmp.disconnect() + except (ConnectionResetError, EOFError, BrokenPipeError): + # ... disconnect() will probably see + # errors too, but we must try to call it + # regardless to cleanup asyncio state + # and prevent python warnings at GC time + pass + return + asyncio.run(main()) + + def test_hotplug_stress(self): + """ + Repeatedly hotplug and unplug a monitor, while another thread + concurrently issues commands on that monitor. This stresses + the synchronization with the monitor thread during cleanup + """ + self.set_machine('none') + self.vm.add_args('-nodefaults') + self.vm.launch() + + # Each loop sleeps at most 0.5 seconds, so this should + # give an upper bound of approx 5 seconds execution + # time which is reasonable to run by default + repeat = 10 + for i in range(repeat): + # First cycle + sock = self._add_monitor() + print ("# stress cycle %02d/%02d" % (i, repeat)) + stress = threading.Thread(target=self.stress_mon, args=[sock]) + stress.start() + # Sleep upto 1/2 second to vary the races + time.sleep(random.random() / 2) + self._remove_monitor() + stress.join() + if __name__ == '__main__': QemuSystemTest.main() -- 2.55.0