fix(plex): a restart that fails to start still deletes the session it moved aside

This commit is contained in:
2026-10-28 21:53:59 +01:00
parent c3ad7684ea
commit 52b93d0014
2 changed files with 128 additions and 64 deletions
+68 -64
View File
@@ -820,74 +820,78 @@ def start_session(
# platform without fork (the API always runs in a Linux container in prod) it's simply omitted.
preexec = _sw_child_preexec if (transcode and not hw and os.name == "posix") else None
doomed: list[tuple[HlsSession, Path | None]] = []
with _lock:
if replace_only is not None and _sessions.get(reg) is not replace_only:
return None # superseded/culled while we waited out of lock — don't clobber the newer one
old = _sessions.pop(reg, None)
if old is not None:
doomed.append(_detach(old))
# An ffmpeg still exiting from THIS path (the old session, or one stopped a moment ago)
# would write into the directory about to be made; see `_dying`.
prev = _dying.pop(directory, None)
if prev is not None:
_await_exit(key, prev)
shutil.rmtree(directory, ignore_errors=True)
directory.mkdir(parents=True, exist_ok=True)
proc = subprocess.Popen(
_ffmpeg_cmd(
src,
start_s,
# Finished even when the new session fails to start (no space, no ffmpeg, a DB error): what
# was moved aside under the lock is otherwise left for a restart's sweep.
try:
with _lock:
if replace_only is not None and _sessions.get(reg) is not replace_only:
return None # superseded/culled while we waited out of lock — don't clobber the newer one
old = _sessions.pop(reg, None)
if old is not None:
doomed.append(_detach(old))
# An ffmpeg still exiting from THIS path (the old session, or one stopped a moment ago)
# would write into the directory about to be made; see `_dying`.
prev = _dying.pop(directory, None)
if prev is not None:
_await_exit(key, prev)
shutil.rmtree(directory, ignore_errors=True)
directory.mkdir(parents=True, exist_ok=True)
proc = subprocess.Popen(
_ffmpeg_cmd(
src,
start_s,
directory,
audio_ord,
aoff,
audio_langs if is_multi else None,
transcode=transcode,
hw=hw,
tonemap=tonemap,
preset=preset,
crf=crf,
max_height=max_height,
loudnorm=loudnorm,
),
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
preexec_fn=preexec,
)
s = HlsSession(
key,
directory,
audio_ord,
aoff,
audio_langs if is_multi else None,
proc,
start_s,
variants,
transcode=transcode,
hw=hw,
tonemap=tonemap,
preset=preset,
crf=crf,
max_height=max_height,
loudnorm=loudnorm,
),
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
preexec_fn=preexec,
)
s = HlsSession(
key,
directory,
proc,
start_s,
variants,
transcode=transcode,
hw=hw,
tonemap=tonemap,
user_id=user_id,
)
_sessions[reg] = s
# The one line that says which pipeline a session actually got. Everything downstream
# — the cap, the HW→SW fallback, the subtitle offset — is about this choice, and until
# now it was only inferable from the ffmpeg command nobody keeps.
log.info(
"an HLS session started",
extra=logs.event(
"plex.stream.session_started",
key=key,
transcode=transcode,
hw=hw,
tonemap=tonemap,
variants=len(variants or ()),
start_s=round(start_s, 1),
),
)
# Admin-configurable caps (Configuration → Plex); at least 1 each so playback can't be
# capped to zero.
doomed += _enforce_caps(
user_id,
max(1, sysconfig.get_int(db, "plex_max_transcodes")),
max(1, sysconfig.get_int(db, "plex_max_sessions")),
)
_finish(doomed)
user_id=user_id,
)
_sessions[reg] = s
# The one line that says which pipeline a session actually got. Everything downstream
# — the cap, the HW→SW fallback, the subtitle offset — is about this choice, and until
# now it was only inferable from the ffmpeg command nobody keeps.
log.info(
"an HLS session started",
extra=logs.event(
"plex.stream.session_started",
key=key,
transcode=transcode,
hw=hw,
tonemap=tonemap,
variants=len(variants or ()),
start_s=round(start_s, 1),
),
)
# Admin-configurable caps (Configuration → Plex); at least 1 each so playback can't be
# capped to zero.
doomed += _enforce_caps(
user_id,
max(1, sysconfig.get_int(db, "plex_max_transcodes")),
max(1, sysconfig.get_int(db, "plex_max_sessions")),
)
finally:
_finish(doomed)
return s
s = _spawn(*_select_encode(db, item, transcode, src))
+60
View File
@@ -1058,3 +1058,63 @@ class TestSessionsPerViewer:
self._start(monkeypatch, user_id=uid)
assert len(stream._sessions) == 3 and (1, "12345") not in stream._sessions
assert oldest.proc.killed and not oldest.transcode
class TestTeardownFinishes:
"""A session taken down by a cap or replaced by its own viewer is only renamed aside under the
lock; it is deleted after. The rename alone already moves the directory and `terminate()` alone
already marks the proc killed — so what is pinned here is the tomb: a whole segmented copy of the
film that only a restart's sweep would otherwise reclaim."""
capturing_env = TestTranscodeStartSession.capturing_env
@staticmethod
def _left_behind(root):
return sorted(p.name for p in root.iterdir() if stream._TOMB in p.name) + sorted(
str(p) for p in stream._dying
)
def test_a_culled_session_is_deleted_not_only_moved_aside(self, capturing_env, monkeypatch):
monkeypatch.setattr(stream, "_dying", {})
first = TestSessionsPerViewer._start(monkeypatch, user_id=1, rating_key="1")
first.last_access -= 60
TestSessionsPerViewer._start(monkeypatch, user_id=1, rating_key="2")
TestSessionsPerViewer._start(monkeypatch, user_id=1, rating_key="3")
assert first.proc.killed and not first.dir.exists()
assert self._left_behind(capturing_env) == []
def test_a_viewers_restart_deletes_the_session_it_replaces(self, capturing_env, monkeypatch):
monkeypatch.setattr(stream, "_dying", {})
monkeypatch.setattr(
stream, "_select_encode", lambda db, item, transcode, src: (False, False)
)
monkeypatch.setattr(
stream, "_probe_first_pts", lambda seg: None
) # no real segment to probe
old = stream.start_session(db=None, user_id=1, item=_FakeItem(), start_s=0.0)
new = stream.start_session(db=None, user_id=1, item=_FakeItem(), start_s=600.0)
assert old.proc.killed and new.dir.exists() and not old.dir.exists()
assert self._left_behind(capturing_env) == []
def test_a_restart_that_fails_to_start_still_deletes_what_it_replaced(
self, capturing_env, monkeypatch
):
# The new ffmpeg cannot start (a full disk, no ffmpeg, no memory): the old session is already
# moved aside, and nothing else in this process would ever delete it.
monkeypatch.setattr(stream, "_dying", {})
monkeypatch.setattr(
stream, "_select_encode", lambda db, item, transcode, src: (False, False)
)
monkeypatch.setattr(
stream, "_probe_first_pts", lambda seg: None
) # no real segment to probe
old = stream.start_session(db=None, user_id=1, item=_FakeItem(), start_s=0.0)
def no_ffmpeg(*args, **kwargs):
raise OSError(28, "No space left on device")
monkeypatch.setattr(stream.subprocess, "Popen", no_ffmpeg)
with pytest.raises(OSError):
stream.start_session(db=None, user_id=1, item=_FakeItem(), start_s=600.0)
assert old.proc.killed and not old.dir.exists()
assert self._left_behind(capturing_env) == []