168 lines
6.2 KiB
Python
168 lines
6.2 KiB
Python
"""Regression tests for #100179: cron-update three-way restart deadlock.
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When `hermes update` runs INSIDE the gateway's own process tree (the
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hermes-auto-update cron job), waiting for that gateway to exit is a
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circular wait:
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gateway waits on all in-flight work units (#77184)
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-> cron agent session waits on the `hermes update` process
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-> `hermes update` waits on the gateway to exit [back to A]
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The wedged-loop probe cannot break it: the cron session posts activity
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every ~180s (process-tool poll return), so it is never marked wedged and
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the gateway burns the full 1800s force-drain cap.
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The fix: when the target gateway PID is an ancestor of this process,
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fire-and-forget (SIGUSR1 + return) instead of drain-waiting.
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"""
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from unittest.mock import patch
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import pytest
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linux_only = pytest.mark.linux_only
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class TestAncestorDetectionGuard:
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"""_is_pid_ancestor_of_current_process is the deadlock discriminator."""
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def test_own_pid_is_ancestor(self):
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import os
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from hermes_cli.gateway import _is_pid_ancestor_of_current_process
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assert _is_pid_ancestor_of_current_process(os.getpid()) is True
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def test_parent_pid_is_ancestor(self):
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import os
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from hermes_cli.gateway import _is_pid_ancestor_of_current_process
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ppid = os.getppid()
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if ppid <= 1:
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pytest.skip("no meaningful parent in this environment")
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assert _is_pid_ancestor_of_current_process(ppid) is True
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def test_unrelated_pid_is_not_ancestor(self):
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from hermes_cli.gateway import _is_pid_ancestor_of_current_process
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# PID 0 / negative are never ancestors; a very high unlikely PID isn't
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# either. Use the documented zero/negative contract for determinism.
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assert _is_pid_ancestor_of_current_process(0) is False
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assert _is_pid_ancestor_of_current_process(-5) is False
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@linux_only
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class TestSelfRestartFireAndForget:
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"""_request_gateway_self_restart signals without waiting for exit."""
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def test_refuses_non_ancestor_pid(self):
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from hermes_cli.gateway import _request_gateway_self_restart
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# A non-ancestor must be refused — signalling an unrelated gateway
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# and returning immediately would skip its drain entirely.
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assert _request_gateway_self_restart(0) is False
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def test_signals_ancestor_and_returns_immediately(self):
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"""The ancestor path sends SIGUSR1 and does NOT poll for exit."""
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import os
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import signal as _signal
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from hermes_cli import gateway as gw
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sent = []
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def _fake_kill(pid, sig):
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sent.append((pid, sig))
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with patch.object(gw.os, "kill", side_effect=_fake_kill), patch.object(
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gw, "_wait_for_pid_exit",
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side_effect=AssertionError(
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"fire-and-forget must NOT wait for the gateway to exit — "
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"that wait is the #100179 deadlock"
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),
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):
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ok = gw._request_gateway_self_restart(os.getpid())
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assert ok is True
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assert sent == [(os.getpid(), _signal.SIGUSR1)]
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def test_graceful_restart_does_wait(self):
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"""Contrast: the non-ancestor path DOES drain-wait (unchanged)."""
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import signal as _signal
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from hermes_cli import gateway as gw
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waited = []
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with patch.object(gw.os, "kill"), patch.object(
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gw, "_wait_for_pid_exit",
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side_effect=lambda pid, t: waited.append((pid, t)) or True,
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):
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ok = gw._graceful_restart_via_sigusr1(4242, drain_timeout=7.0)
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assert ok is True
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assert waited == [(4242, 7.0)], "drain path must still wait for exit"
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class TestDrainOrSignalTriage:
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"""_drain_or_signal_gateway_for_update routes the three cases correctly."""
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def _patched(self, monkeypatch, *, ancestor, wedged):
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from hermes_cli import gateway as gw
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calls = {"self_restart": [], "escalate": [], "drain": []}
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monkeypatch.setattr(
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gw, "_is_pid_ancestor_of_current_process", lambda pid: ancestor
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)
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monkeypatch.setattr(
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gw,
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"probe_gateway_loop_liveness",
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lambda pid: gw.GATEWAY_LOOP_WEDGED if wedged else "alive",
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)
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monkeypatch.setattr(
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gw,
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"_request_gateway_self_restart",
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lambda pid: calls["self_restart"].append(pid) or True,
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)
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monkeypatch.setattr(
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gw, "_escalate_wedged_gateway", lambda pid: calls["escalate"].append(pid)
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)
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monkeypatch.setattr(
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gw,
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"_graceful_restart_via_sigusr1",
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lambda pid, drain_timeout: calls["drain"].append((pid, drain_timeout))
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or True,
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)
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return calls
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def test_ancestor_gateway_is_signalled_fire_and_forget(self, monkeypatch):
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"""In-tree gateway (#100179): SIGUSR1 request, NO drain wait."""
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from hermes_cli.update_cmd import _drain_or_signal_gateway_for_update
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calls = self._patched(monkeypatch, ancestor=True, wedged=False)
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assert _drain_or_signal_gateway_for_update(1234, 900.0, "svc") is True
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assert calls["self_restart"] == [1234]
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assert calls["drain"] == [], "drain-waiting on an ancestor IS the deadlock"
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assert calls["escalate"] == []
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def test_wedged_gateway_is_escalated(self, monkeypatch):
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"""Provably-dead loop (#81642): bounded escalation, no drain wait."""
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from hermes_cli.update_cmd import _drain_or_signal_gateway_for_update
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calls = self._patched(monkeypatch, ancestor=False, wedged=True)
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assert _drain_or_signal_gateway_for_update(1234, 900.0, "svc") is True
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assert calls["escalate"] == [1234]
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assert calls["drain"] == []
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assert calls["self_restart"] == []
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def test_live_out_of_tree_gateway_still_drain_waits(self, monkeypatch):
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"""Normal out-of-tree update keeps the full graceful drain semantics."""
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from hermes_cli.update_cmd import _drain_or_signal_gateway_for_update
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calls = self._patched(monkeypatch, ancestor=False, wedged=False)
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assert _drain_or_signal_gateway_for_update(1234, 900.0, "svc") is True
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assert calls["drain"] == [(1234, 900.0)]
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assert calls["self_restart"] == []
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assert calls["escalate"] == []
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