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dashboard: serialize mp3 decode to avoid libsndfile SIGBUS #13

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dashboard: serialize mp3 decode to avoid libsndfile SIGBUS #13

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11 changes: 10 additions & 1 deletion dashboard/server.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3006,6 +3006,14 @@ def _extract_hyperparams(run):
SPEC_W, SPEC_H = 300, 60
_spec_pool = ThreadPoolExecutor(max_workers=4)

# libsndfile 1.2.2's MPEG decoder reports errors by longjmp-ing through a
# process-global jmpbuf (libmpg123). Two threads decoding mp3s at once race on
# it: one clobbers the other's saved context, the longjmp lands on a dead stack
# frame, and the process takes SIGBUS (pc=0x1, EXC_ARM_DA_ALIGN) inside
# mpeg_init. We fan out decodes from _spec_pool, a 16-worker pool, and the
# threaded HTTP server, so serialize every sf.read behind this lock.
_sndfile_lock = threading.Lock()

# Pre-compute band colors as (3, 3) array for vectorized multiply
_BAND_COLORS = np.array([c for _, _, c in SPEC_BANDS], dtype=np.float32)

Expand Down Expand Up @@ -3067,7 +3075,8 @@ def _power_to_db(S, top_db=80.0):

def _load_audio(path, target_sr=32000):
"""Load + resample to target_sr. Returns (channels, samples) like librosa(mono=False)."""
y, sr = sf.read(str(path), dtype='float32', always_2d=False)
with _sndfile_lock: # see _sndfile_lock: concurrent mp3 decode is a SIGBUS
y, sr = sf.read(str(path), dtype='float32', always_2d=False)
if y.ndim == 2:
y = y.T # soundfile gives (n, c); we want (c, n)
if sr != target_sr:
Expand Down