Import AITURK IDE 1.0.0-beta.1 from Hermes 63279301; preserve MIT license

tests/cron/test_cron_emfile_stall_87644.py

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+"""Regression tests for #87644 — cron scheduler silently stalls after EMFILE.
+
+Three fixes under test:
+
+1. ``tick()`` no longer swallows a real ``OSError`` at tick-lock acquisition as
+   "another instance holds the lock".  An EMFILE/ENFILE (fd exhaustion) on
+   ``open(.tick.lock)`` previously made ``tick()`` return 0 — which the ticker
+   loop recorded as a *successful* tick and cleared the error — so the
+   scheduler looked perfectly healthy (heartbeat + success markers fresh)
+   while no job ever ran again.  Now the failure propagates to the ticker
+   loop, which records it and backs off.
+
+2. The ticker loop detects fd exhaustion (EMFILE/ENFILE/"Too many open
+   files"), attempts best-effort fd reclamation (``gc.collect()`` + raising
+   the soft nofile limit), and applies exponential backoff so an exhausted
+   process stops hammering the store every 60s.  Once FDs free up, the next
+   tick succeeds and the backoff resets — the scheduler self-heals without a
+   gateway restart.
+
+3. Genuine lock contention (EWOULDBLOCK/EAGAIN on flock) still skips the tick
+   silently — that behavior is preserved.
+"""
+import errno
+import threading
+import time
+from unittest.mock import patch
+
+import pytest
+
+import cron.scheduler as scheduler_mod
+
+try:
+    import fcntl
+except ImportError:  # pragma: no cover - non-POSIX
+    fcntl = None
+
+pytestmark = pytest.mark.skipif(fcntl is None, reason="flock semantics are POSIX-only")
+
+
+def _wait_until(predicate, timeout=10.0, interval=0.005):
+    """Block until ``predicate()`` is truthy or ``timeout`` elapses."""
+    deadline = time.monotonic() + timeout
+    while time.monotonic() < deadline:
+        value = predicate()
+        if value:
+            return value
+        time.sleep(interval)
+    return predicate()
+
+
+# ── Fix 1: tick() must not swallow EMFILE as "another instance holds the lock" ─
+
+
+class TestTickLockEmfileNotSwallowed:
+    def test_lock_open_emfile_raises_instead_of_silent_skip(self, monkeypatch):
+        """open(.tick.lock) raising EMFILE must propagate — not return 0 as if
+        another ticker held the lock (the pre-fix silent stall)."""
+        real_open = open
+        calls = []
+
+        def flaky_open(path, *args, **kwargs):
+            if str(path).endswith(".tick.lock"):
+                calls.append(("emfile", str(path)))
+                raise OSError(errno.EMFILE, "Too many open files")
+            return real_open(path, *args, **kwargs)
+
+        monkeypatch.setattr("builtins.open", flaky_open)
+        with pytest.raises(OSError) as excinfo:
+            scheduler_mod.tick(verbose=False)
+        assert excinfo.value.errno == errno.EMFILE
+        assert calls, "the lock file open must have been attempted"
+
+    def test_lock_flock_emfile_raises(self, monkeypatch):
+        """flock() raising EMFILE (fd exhaustion at lock syscall) must also
+        propagate — only EWOULDBLOCK/EAGAIN/EACCES mean contention."""
+        with patch.object(fcntl, "flock", side_effect=OSError(errno.EMFILE, "Too many open files")):
+            with pytest.raises(OSError) as excinfo:
+                scheduler_mod.tick(verbose=False)
+        assert excinfo.value.errno == errno.EMFILE
+
+    def test_lock_contention_ewouldblock_still_skips_silently(self, monkeypatch):
+        """Genuine contention (another ticker holds the lock) still returns 0
+        silently — the cross-process mutual-exclusion contract is preserved."""
+        with patch.object(fcntl, "flock", side_effect=OSError(errno.EWOULDBLOCK, "Resource temporarily unavailable")):
+            assert scheduler_mod.tick(verbose=False) == 0
+
+    def test_lock_contention_eagain_still_skips(self):
+        with patch.object(fcntl, "flock", side_effect=OSError(errno.EAGAIN, "Resource temporarily unavailable")):
+            assert scheduler_mod.tick(verbose=False) == 0
+
+
+# ── Fix 2: ticker loop survives EMFILE, reclaims fds, backs off, self-heals ──
+
+
+class TestTickerEmfileBackoff:
+    def test_emfile_tick_records_error_and_keeps_looping(self, monkeypatch):
+        """An EMFILE tick must be recorded as a FAILED tick (not success) and
+        the loop must keep running — the pre-fix state where the scheduler
+        stalled silently while the heartbeat kept reporting healthy."""
+        from cron.scheduler_provider import InProcessCronScheduler
+
+        beats = []
+        errors = []
+        stop = threading.Event()
+        prov = InProcessCronScheduler()
+
+        with patch(
+            "cron.scheduler.tick",
+            side_effect=OSError(errno.EMFILE, "Too many open files"),
+        ), patch(
+            "cron.jobs.record_ticker_heartbeat",
+            side_effect=lambda success=False: beats.append(success),
+        ), patch(
+            "cron.jobs.record_ticker_error",
+            side_effect=lambda msg: errors.append(msg),
+        ), patch("cron.jobs.clear_ticker_error") as clear:
+            t = threading.Thread(target=prov.start, args=(stop,), kwargs={"interval": 0}, daemon=True)
+            t.start()
+            assert _wait_until(lambda: len(beats) >= 3), "ticker did not keep beating"
+            stop.set()
+            t.join(timeout=5)
+
+        assert not t.is_alive(), "ticker must survive EMFILE ticks"
+        assert errors, "ticker error must be persisted so `hermes cron status` can show it"
+        assert "Too many open files" in errors[0]
+        # Every post-failure beat must be success=False: liveness yes, success no.
+        assert beats[-1] is False
+        clear.assert_not_called()
+
+    def test_emfile_triggers_fd_reclamation(self, monkeypatch):
+        """The ticker must attempt best-effort fd reclamation on EMFILE so the
+        next tick can succeed once descriptors free up."""
+        from cron.scheduler_provider import InProcessCronScheduler
+
+        reclaimed = []
+        stop = threading.Event()
+        prov = InProcessCronScheduler()
+
+        with patch(
+            "cron.scheduler.tick",
+            side_effect=OSError(errno.EMFILE, "Too many open files"),
+        ), patch(
+            "cron.scheduler._reclaim_fds_best_effort",
+            side_effect=lambda: reclaimed.append(1),
+        ), patch("cron.jobs.record_ticker_heartbeat"), patch("cron.jobs.record_ticker_error"):
+            t = threading.Thread(target=prov.start, args=(stop,), kwargs={"interval": 0}, daemon=True)
+            t.start()
+            assert _wait_until(lambda: len(reclaimed) >= 1), "fd reclamation never ran"
+            stop.set()
+            t.join(timeout=5)
+
+        assert len(reclaimed) >= 1
+
+    def test_ticker_recovers_after_emfile_clears(self, monkeypatch):
+        """Once ticks stop raising EMFILE, the next tick succeeds, the error is
+        cleared and the success marker is bumped again — self-healing without a
+        gateway restart."""
+        from cron.scheduler_provider import InProcessCronScheduler
+
+        attempts = {"n": 0}
+        beats = []
+        errors = []
+        stop = threading.Event()
+        prov = InProcessCronScheduler()
+
+        def flaky_tick(*args, **kwargs):
+            attempts["n"] += 1
+            if attempts["n"] <= 2:
+                raise OSError(errno.EMFILE, "Too many open files")
+            return 0
+
+        with patch("cron.scheduler.tick", side_effect=flaky_tick), patch(
+            "cron.jobs.record_ticker_heartbeat",
+            side_effect=lambda success=False: beats.append(success),
+        ), patch(
+            "cron.jobs.record_ticker_error",
+            side_effect=lambda msg: errors.append(msg),
+        ), patch("cron.jobs.clear_ticker_error") as clear, patch(
+            "cron.scheduler._reclaim_fds_best_effort"
+        ):
+            t = threading.Thread(target=prov.start, args=(stop,), kwargs={"interval": 0}, daemon=True)
+            t.start()
+            # Wait until we've seen at least one success beat AFTER the failures.
+            assert _wait_until(lambda: len(beats) >= 4), "ticker never recovered"
+            stop.set()
+            t.join(timeout=5)
+
+        assert not t.is_alive()
+        assert attempts["n"] >= 3
+        assert errors, "failures must be recorded"
+        assert True in beats, "a successful tick must bump the success marker"
+        clear.assert_called(), "a successful tick must clear the recorded error"
+
+
+# ── Helpers ────────────────────────────────────────────────────────────────────
+
+
+class TestEmfileHelpers:
+    def test_is_fd_exhaustion_errno(self):
+        assert scheduler_mod._is_fd_exhaustion(OSError(errno.EMFILE, "Too many open files"))
+        assert scheduler_mod._is_fd_exhaustion(OSError(errno.ENFILE, "file table overflow"))
+        assert not scheduler_mod._is_fd_exhaustion(OSError(errno.EACCES, "Permission denied"))
+        assert not scheduler_mod._is_fd_exhaustion(OSError(errno.EWOULDBLOCK, "Resource temporarily unavailable"))
+
+    def test_is_fd_exhaustion_wrapped_message(self):
+        """load_jobs wraps the raw OSError in a RuntimeError whose message
+        carries the errno text — the ticker must classify that too."""
+        assert scheduler_mod._is_fd_exhaustion(
+            RuntimeError("Failed to read cron database: [Errno 24] Too many open files")
+        )
+
+    def test_reclaim_fds_best_effort_never_raises(self):
+        # gc.collect + apply_nofile_soft_limit are both best-effort; the helper
+        # must tolerate missing/refusing platforms without raising.
+        assert scheduler_mod._reclaim_fds_best_effort() is None
+
+    def test_lock_contention_errno_classification(self):
+        assert scheduler_mod._is_lock_contention_errno(OSError(errno.EWOULDBLOCK, "x"))
+        assert scheduler_mod._is_lock_contention_errno(OSError(errno.EAGAIN, "x"))
+        assert not scheduler_mod._is_lock_contention_errno(OSError(errno.EMFILE, "x"))
+        assert not scheduler_mod._is_lock_contention_errno(OSError(errno.ENFILE, "x"))