unsloth/studio/backend/tests/test_training_nan_loss_handling.py

123 lines
4.5 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
"""Pin Studio's behavior when a training event reports non-finite (NaN/Inf) loss.
The event handler used to filter NaN/Inf to None silently while leaving the
previous finite loss in progress.loss, so the API kept reporting the stale
value. We now clear it: clients see loss=None at the affected step and a
one-shot warning is logged. Training continues; the run is not marked failed.
"""
from __future__ import annotations
import math
import os
import sys
import pytest
_BACKEND = os.path.join(os.path.dirname(__file__), "..")
if _BACKEND not in sys.path:
sys.path.insert(0, _BACKEND)
from core.training.training import TrainingBackend
def _make_backend() -> TrainingBackend:
return TrainingBackend()
def _progress_event(step: int, loss: float, lr: float = 1e-4) -> dict:
return {
"type": "progress",
"step": step,
"loss": loss,
"learning_rate": lr,
"epoch": 0.0,
"total_steps": 100,
}
class TestNonfiniteLossSoftHandling:
def test_finite_loss_updates_progress_normally(self):
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=0.97))
assert b._progress.loss == pytest.approx(0.97)
assert b._progress.error is None
assert b._should_stop is False
assert b._nonfinite_loss_warned is False
def test_nan_loss_clears_progress_loss(self):
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=0.97))
assert b._progress.loss == pytest.approx(0.97)
b._handle_event(_progress_event(step=2, loss=float("nan")))
# Stale finite loss must NOT leak through
assert b._progress.loss is None
# Run is not marked failed
assert b._progress.error is None
assert b._should_stop is False
# Warning flag is set so we don't re-log on every subsequent NaN step
assert b._nonfinite_loss_warned is True
def test_inf_loss_clears_progress_loss(self):
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=float("inf")))
assert b._progress.loss is None
assert b._progress.error is None
assert b._should_stop is False
assert b._nonfinite_loss_warned is True
def test_negative_inf_loss_clears_progress_loss(self):
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=float("-inf")))
assert b._progress.loss is None
assert b._progress.error is None
assert b._should_stop is False
assert b._nonfinite_loss_warned is True
def test_repeated_nan_only_warns_once(self, monkeypatch):
"""Only the first NaN logs a warning; later NaNs stay quiet."""
import core.training.training as training_module
warnings = []
monkeypatch.setattr(
training_module,
"logger",
type(
"LoggerStub",
(),
{
"warning": lambda self, *a, **k: warnings.append(a),
"info": lambda self, *a, **k: None,
"debug": lambda self, *a, **k: None,
"error": lambda self, *a, **k: None,
},
)(),
)
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=0.97))
b._handle_event(_progress_event(step=2, loss=float("nan")))
assert b._nonfinite_loss_warned is True
assert len(warnings) == 1
# Further NaN steps stay quiet
b._handle_event(_progress_event(step=3, loss=float("nan")))
b._handle_event(_progress_event(step=4, loss=float("nan")))
assert len(warnings) == 1
assert b._nonfinite_loss_warned is True
assert b._progress.loss is None
assert b._progress.error is None
assert b._should_stop is False
def test_recovery_updates_loss_when_finite_again(self):
"""If a NaN step is followed by a finite step, progress.loss must
reflect the new finite value (not stay stuck at None)."""
b = _make_backend()
b._handle_event(_progress_event(step=1, loss=0.97))
b._handle_event(_progress_event(step=2, loss=float("nan")))
assert b._progress.loss is None
b._handle_event(_progress_event(step=3, loss=0.85))
assert b._progress.loss == pytest.approx(0.85)
# Warning flag stays set (we don't reset it on recovery)
assert b._nonfinite_loss_warned is True