Files
giant/tests/test_router.py
T
lars bac541240f Add mixture-of-experts routing prototype for Stage 1 and Stage 2
Both stages can now route through a pluggable Router (EnergyRouter as the
first implementation, a soft turn-on gate over pre-step log-energy) into
several small ExpertTrunks instead of one monolithic trunk. Trains as a
differentiable soft mixture and dispatches to a single expert per row at
eval time, which is the source of the per-call speedup this prototype is
after (issue #5's ~10x native-Geant4 budget). Disabled by default, so
existing configs/checkpoints are unaffected; build_models() centralizes
routed-vs-monolith construction across train/predict/rollout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-07-08 15:17:19 +02:00

297 lines
9.2 KiB
Python

"""Tests for the mixture-of-experts routing prototype (giant/model/network.py)."""
import torch
from giant.constants import COND_DIM, K_MAX, SEC_DIM, X_DIM
from giant.model.network import (
DenoisingMLP,
EnergyRouter,
ROUTER_REGISTRY,
RoutedDenoisingMLP,
RoutedSecondaryDecoder,
SecondaryDecoder,
build_models,
build_router,
)
def _cond(B=8, pdg=3, mat=2):
cond_cont = torch.randn(B, COND_DIM)
cond_cat = torch.stack(
[torch.randint(0, pdg, (B,)), torch.randint(0, mat, (B,))], dim=1
)
return cond_cont, cond_cat
def _routed_stage1(n_experts=4, pdg=3, mat=2, **router_kwargs):
router = build_router("energy", n_experts, **router_kwargs)
return RoutedDenoisingMLP(
pdg_vocab=pdg,
mat_vocab=mat,
router=router,
expert_hidden_dim=16,
expert_n_blocks=2,
)
def _routed_sec_decoder(n_experts=4, pdg=3, mat=2, **router_kwargs):
router = build_router("energy", n_experts, **router_kwargs)
return RoutedSecondaryDecoder(
pdg_vocab=pdg,
mat_vocab=mat,
router=router,
expert_hidden_dim=16,
expert_n_blocks=2,
)
# ── Router / EnergyRouter contract ──────────────────────────────────────────
def test_energy_router_registered():
assert ROUTER_REGISTRY["energy"] is EnergyRouter
def test_energy_router_gate_partition_of_unity():
router = EnergyRouter(n_experts=4)
cond_cont, cond_cat = _cond(16)
g = router.gate(cond_cont, cond_cat)
assert g.shape == (16, 4)
torch.testing.assert_close(g.sum(dim=-1), torch.ones(16), atol=1e-5, rtol=0)
def test_energy_router_top1_matches_gate_argmax():
router = EnergyRouter(n_experts=4)
cond_cont, cond_cat = _cond(16)
assert torch.equal(
router.top1(cond_cont, cond_cat), router.gate(cond_cont, cond_cat).argmax(-1)
)
def test_energy_router_hardens_as_temperature_shrinks():
"""As tau -> 0 the soft gate should converge to a one-hot at the argmax."""
router = EnergyRouter(n_experts=4, temperature=1e-4)
cond_cont, cond_cat = _cond(16)
g = router.gate(cond_cont, cond_cat)
top1 = router.top1(cond_cont, cond_cat)
onehot = torch.nn.functional.one_hot(top1, num_classes=4).float()
torch.testing.assert_close(g, onehot, atol=1e-3, rtol=0)
def test_energy_router_balance_loss_is_nonnegative_scalar():
router = EnergyRouter(n_experts=4)
cond_cont, cond_cat = _cond(16)
loss = router.balance_loss(cond_cont, cond_cat)
assert loss.shape == ()
assert loss.item() >= 0.0
def test_build_router_ignores_unrecognized_kwargs():
# lambda_balance is a model_config.router key but not an EnergyRouter kwarg
router = build_router("energy", 4, temperature=0.3, lambda_balance=0.5)
assert isinstance(router, EnergyRouter)
assert router.temperature == 0.3
def test_build_router_unknown_type_raises():
try:
build_router("nonexistent", 4)
except ValueError:
return
raise AssertionError("expected ValueError for unknown router type")
# ── RoutedDenoisingMLP ───────────────────────────────────────────────────────
def test_routed_denoising_mlp_output_shape_train_and_eval():
B = 8
model = _routed_stage1()
x_t = torch.randn(B, X_DIM)
t = torch.rand(B)
cond_cont, cond_cat = _cond(B)
model.train()
out_train = model(x_t, t, cond_cont, cond_cat)
assert out_train.shape == (B, X_DIM)
model.eval()
with torch.no_grad():
out_eval = model(x_t, t, cond_cont, cond_cat)
assert out_eval.shape == (B, X_DIM)
def test_routed_denoising_mlp_gradients_flow_in_train_mode():
"""Soft mixture in train mode should touch every expert's parameters."""
B = 8
model = _routed_stage1(n_experts=3)
x_t = torch.randn(B, X_DIM)
t = torch.rand(B)
cond_cont, cond_cat = _cond(B)
model.train()
flow_loss = model(x_t, t, cond_cont, cond_cat).sum()
nsec_loss = model.predict_n_sec(cond_cont, cond_cat).sum()
(flow_loss + nsec_loss).backward()
for name, p in model.named_parameters():
assert p.grad is not None, f"no grad for {name}"
def test_routed_denoising_mlp_eval_dispatch_matches_manual_grouping():
"""Eval-mode grouped top-1 dispatch must equal running each row through
its assigned expert individually (batch order shouldn't matter)."""
B = 12
model = _routed_stage1(n_experts=4)
model.eval()
x_t = torch.randn(B, X_DIM)
t = torch.rand(B)
cond_cont, cond_cat = _cond(B)
with torch.no_grad():
batched = model(x_t, t, cond_cont, cond_cat)
t_emb = model.time_emb(t)
c_emb = model.cond_enc(cond_cont, cond_cat)
cond = torch.cat([t_emb, c_emb], dim=-1)
idx = model.router.top1(cond_cont, cond_cat)
manual = torch.zeros_like(x_t)
for i in range(B):
manual[i] = model.experts[int(idx[i])](x_t[i : i + 1], cond[i : i + 1])[0]
torch.testing.assert_close(batched, manual, atol=1e-5, rtol=1e-4)
def test_routed_denoising_mlp_predict_n_sec_shape():
B = 6
model = _routed_stage1()
cond_cont, cond_cat = _cond(B)
logits = model.predict_n_sec(cond_cont, cond_cat)
assert logits.shape == (B, K_MAX + 1)
def test_routed_denoising_mlp_pdg_embedding_weight_shape():
model = _routed_stage1(pdg=5, mat=2)
from giant.constants import EMB_DIM
assert model.pdg_embedding_weight().shape == (5, EMB_DIM)
# ── RoutedSecondaryDecoder ───────────────────────────────────────────────────
def test_routed_secondary_decoder_output_shape_train_and_eval():
B = 8
decoder = _routed_sec_decoder()
x_t = torch.randn(B, SEC_DIM)
t = torch.rand(B)
cond_cont, cond_cat = _cond(B)
stage1_out = torch.randn(B, X_DIM)
decoder.train()
out_train = decoder(x_t, t, cond_cont, cond_cat, stage1_out)
assert out_train.shape == (B, SEC_DIM)
decoder.eval()
with torch.no_grad():
out_eval = decoder(x_t, t, cond_cont, cond_cat, stage1_out)
assert out_eval.shape == (B, SEC_DIM)
def test_routed_secondary_decoder_gradients_flow():
B = 4
decoder = _routed_sec_decoder(n_experts=3)
x_t = torch.randn(B, SEC_DIM)
t = torch.rand(B)
cond_cont, cond_cat = _cond(B)
stage1_out = torch.randn(B, X_DIM)
decoder.train()
decoder(x_t, t, cond_cont, cond_cat, stage1_out).sum().backward()
for name, p in decoder.named_parameters():
assert p.grad is not None, f"no grad for {name}"
# ── build_models dispatch ────────────────────────────────────────────────────
def test_build_models_monolith_when_router_absent():
model_config = dict(
pdg_vocab=4,
mat_vocab=2,
hidden_dim=32,
n_blocks=2,
emb_dim=16,
dropout=0.1,
k_max=K_MAX,
)
stage1, sec_decoder = build_models(model_config)
assert isinstance(stage1, DenoisingMLP)
assert isinstance(sec_decoder, SecondaryDecoder)
def test_build_models_monolith_when_router_disabled():
model_config = dict(
pdg_vocab=4,
mat_vocab=2,
hidden_dim=32,
n_blocks=2,
emb_dim=16,
dropout=0.1,
k_max=K_MAX,
router={"enabled": False, "type": "energy", "n_experts": 4},
)
stage1, sec_decoder = build_models(model_config)
assert isinstance(stage1, DenoisingMLP)
assert isinstance(sec_decoder, SecondaryDecoder)
def test_build_models_routed_when_enabled():
model_config = dict(
pdg_vocab=4,
mat_vocab=2,
emb_dim=16,
dropout=0.1,
k_max=K_MAX,
expert_hidden_dim=16,
expert_n_blocks=2,
router={
"enabled": True,
"type": "energy",
"n_experts": 4,
"temperature": 0.5,
"learn_centers": True,
"lambda_balance": 0.0,
},
)
stage1, sec_decoder = build_models(model_config)
assert isinstance(stage1, RoutedDenoisingMLP)
assert isinstance(sec_decoder, RoutedSecondaryDecoder)
assert len(stage1.experts) == 4
assert len(sec_decoder.experts) == 4
def test_build_models_routed_pair_is_drop_in_for_sample_flow():
"""Exercise the exact calling convention giant/sample.py uses."""
from giant.sample import sample_flow, sample_secondaries
model_config = dict(
pdg_vocab=3,
mat_vocab=2,
emb_dim=16,
dropout=0.1,
k_max=K_MAX,
expert_hidden_dim=8,
expert_n_blocks=1,
router={"enabled": True, "type": "energy", "n_experts": 2},
)
stage1, sec_decoder = build_models(model_config)
B = 5
cond_cont, cond_cat = _cond(B, pdg=3, mat=2)
stage1_norm, n_sec_pred = sample_flow(stage1, cond_cont, cond_cat, steps=2)
assert stage1_norm.shape == (B, X_DIM)
assert n_sec_pred.shape == (B,)
sec_cont, sec_type_emb, sec_valid = sample_secondaries(
sec_decoder, cond_cont, cond_cat, stage1_norm, n_sec_pred, steps=2
)
assert sec_cont.shape == (B, K_MAX, 4)
assert sec_valid.shape == (B, K_MAX)