Register torch.linalg.LinAlgError to pyro exception handling (#1607)

Summary:
Pull Request resolved: #1607

Uses draft changes from pyro-ppl/pyro#3168 (part of pyro 1.8.4 pulled in via D42331876) to register handling of `torch.linalg.LinAlgError` and the `ValueError` that can be raised in the torch distribution's `__init__()`

Reviewed By: saitcakmak

Differential Revision: D42159791

fbshipit-source-id: 3bbe2433b83bd114edd277e42f0017010ac9199f

botorch/models/fully_bayesian.py

@@ -32,7 +32,6 @@
 
 
 import math
-import warnings
 from abc import abstractmethod
 from typing import Any, Dict, List, Mapping, Optional, Tuple
 
@@ -56,14 +55,28 @@
 from gpytorch.means.constant_mean import ConstantMean
 from gpytorch.means.mean import Mean
 from gpytorch.models.exact_gp import ExactGP
-from linear_operator import settings
+from pyro.ops.integrator import register_exception_handler
 from torch import Tensor
 
 MIN_INFERRED_NOISE_LEVEL = 1e-6
 
 _sqrt5 = math.sqrt(5)
 
 
+def _handle_torch_linalg(exception: Exception) -> bool:
+    return type(exception) == torch.linalg.LinAlgError
+
+
+def _handle_valerr_in_dist_init(exception: Exception) -> bool:
+    if not type(exception) == ValueError:
+        return False
+    return "satisfy the constraint PositiveDefinite()" in str(exception)
+
+
+register_exception_handler("torch_linalg", _handle_torch_linalg)
+register_exception_handler("valerr_in_dist_init", _handle_valerr_in_dist_init)
+
+
 def matern52_kernel(X: Tensor, lengthscale: Tensor) -> Tensor:
     """Matern-5/2 kernel."""
     dist = compute_dists(X=X, lengthscale=lengthscale)
@@ -82,51 +95,6 @@ def reshape_and_detach(target: Tensor, new_value: Tensor) -> None:
     return new_value.detach().clone().view(target.shape).to(target)
 
 
-def _psd_safe_pyro_mvn_sample(
-    name: str, loc: Tensor, covariance_matrix: Tensor, obs: Tensor
-) -> None:
-    r"""Wraps the `pyro.sample` call in a loop to add an increasing series of jitter
-    to the covariance matrix each time we get a LinAlgError.
-
-    This is modelled after linear_operator's `psd_safe_cholesky`.
-    """
-    jitter = settings.cholesky_jitter.value(loc.dtype)
-    max_tries = settings.cholesky_max_tries.value()
-    for i in range(max_tries + 1):
-        jitter_matrix = (
-            torch.eye(
-                covariance_matrix.shape[-1],
-                device=covariance_matrix.device,
-                dtype=covariance_matrix.dtype,
-            )
-            * jitter
-        )
-        jittered_covar = (
-            covariance_matrix if i == 0 else covariance_matrix + jitter_matrix
-        )
-        try:
-            pyro.sample(
-                name,
-                pyro.distributions.MultivariateNormal(
-                    loc=loc,
-                    covariance_matrix=jittered_covar,
-                ),
-                obs=obs,
-            )
-            return
-        except (torch.linalg.LinAlgError, ValueError) as e:
-            if isinstance(e, ValueError) and "satisfy the constraint" not in str(e):
-                # Not-PSD can be also caught in Distribution.__init__ during parameter
-                # validation, which raises a ValueError. Only catch those errors.
-                raise e
-            jitter = jitter * 10
-            warnings.warn(
-                "Received a linear algebra error while sampling with Pyro. Adding a "
-                f"jitter of {jitter} to the covariance matrix and retrying.",
-                RuntimeWarning,
-            )
-
-
 class PyroModel:
     r"""
     Base class for a Pyro model; used to assist in learning hyperparameters.
@@ -208,12 +176,14 @@ def sample(self) -> None:
         mean = self.sample_mean(**tkwargs)
         noise = self.sample_noise(**tkwargs)
         lengthscale = self.sample_lengthscale(dim=self.ard_num_dims, **tkwargs)
-        k = matern52_kernel(X=self.train_X, lengthscale=lengthscale)
-        k = outputscale * k + noise * torch.eye(self.train_X.shape[0], **tkwargs)
-        _psd_safe_pyro_mvn_sample(
-            name="Y",
-            loc=mean.view(-1).expand(self.train_X.shape[0]),
-            covariance_matrix=k,
+        K = matern52_kernel(X=self.train_X, lengthscale=lengthscale)
+        K = outputscale * K + noise * torch.eye(self.train_X.shape[0], **tkwargs)
+        pyro.sample(
+            "Y",
+            pyro.distributions.MultivariateNormal(
+                loc=mean.view(-1).expand(self.train_X.shape[0]),
+                covariance_matrix=K,
+            ),
             obs=self.train_Y.squeeze(-1),
         )
 

botorch/models/fully_bayesian_multitask.py

@@ -14,7 +14,6 @@
 import torch
 from botorch.acquisition.objective import PosteriorTransform
 from botorch.models.fully_bayesian import (
-    _psd_safe_pyro_mvn_sample,
     matern52_kernel,
     MIN_INFERRED_NOISE_LEVEL,
     PyroModel,
@@ -94,20 +93,22 @@ def sample(self) -> None:
         noise = self.sample_noise(**tkwargs)
 
         lengthscale = self.sample_lengthscale(dim=self.ard_num_dims, **tkwargs)
-        k = matern52_kernel(X=self.train_X[..., base_idxr], lengthscale=lengthscale)
+        K = matern52_kernel(X=self.train_X[..., base_idxr], lengthscale=lengthscale)
 
         # compute task covar matrix
         task_latent_features = self.sample_latent_features(**tkwargs)[task_indices]
         task_lengthscale = self.sample_task_lengthscale(**tkwargs)
         task_covar = matern52_kernel(
             X=task_latent_features, lengthscale=task_lengthscale
         )
-        k = k.mul(task_covar)
-        k = outputscale * k + noise * torch.eye(self.train_X.shape[0], **tkwargs)
-        _psd_safe_pyro_mvn_sample(
-            name="Y",
-            loc=mean.view(-1).expand(self.train_X.shape[0]),
-            covariance_matrix=k,
+        K = K.mul(task_covar)
+        K = outputscale * K + noise * torch.eye(self.train_X.shape[0], **tkwargs)
+        pyro.sample(
+            "Y",
+            pyro.distributions.MultivariateNormal(
+                loc=mean.view(-1).expand(self.train_X.shape[0]),
+                covariance_matrix=K,
+            ),
             obs=self.train_Y.squeeze(-1),
         )
 

test/models/test_fully_bayesian.py

@@ -6,7 +6,6 @@
 
 
 import itertools
-import warnings
 from unittest import mock
 
 import pyro
@@ -35,7 +34,6 @@
 from botorch.models import ModelList, ModelListGP
 from botorch.models.deterministic import GenericDeterministicModel
 from botorch.models.fully_bayesian import (
-    _psd_safe_pyro_mvn_sample,
     MCMC_DIM,
     MIN_INFERRED_NOISE_LEVEL,
     PyroModel,
@@ -55,6 +53,7 @@
 from gpytorch.likelihoods import FixedNoiseGaussianLikelihood, GaussianLikelihood
 from gpytorch.means import ConstantMean
 from linear_operator.operators import to_linear_operator
+from pyro.ops.integrator import potential_grad, register_exception_handler
 
 
 EXPECTED_KEYS = [
@@ -665,61 +664,55 @@ def f(x):
                     )
                 )
 
-    def test_psd_safe_pyro_mvn_sample(self):
-        def mock_init(
-            batch_shape=torch.Size(),  # noqa
-            event_shape=torch.Size(),  # noqa
-            validate_args=None,
-        ):
-            self._batch_shape = batch_shape
-            self._event_shape = event_shape
-            self._validate_args = False
-
-        for dtype in (torch.float, torch.double):
-            tkwargs = {"dtype": dtype, "device": self.device}
-            loc = torch.rand(5, **tkwargs)
-            obs = torch.rand(5, **tkwargs)
-            psd_covar = torch.eye(5, **tkwargs)
-            not_psd_covar = torch.ones(5, 5, **tkwargs)
-            with warnings.catch_warnings(record=True) as ws:
-                warnings.simplefilter("always")
-                _psd_safe_pyro_mvn_sample(
-                    name="Y", loc=loc, covariance_matrix=psd_covar, obs=obs
-                )
-            self.assertFalse(any("linear algebra error" in str(w.message) for w in ws))
-            # With a PSD covar, it should only get called once.
-            # Raised as a ValueError:
-            with warnings.catch_warnings(record=True) as ws:
-                warnings.simplefilter("always")
-                _psd_safe_pyro_mvn_sample(
-                    name="Y", loc=loc, covariance_matrix=not_psd_covar, obs=obs
-                )
-            self.assertTrue(any("linear algebra error" in str(w.message) for w in ws))
-            # Raised as a LinAlgError:
-            with mock.patch(
-                "torch.distributions.multivariate_normal.Distribution.__init__",
-                wraps=mock_init,
-            ), mock.patch(
-                "pyro.distributions.MultivariateNormal",
-                wraps=pyro.distributions.MultivariateNormal,
-            ) as mock_mvn, warnings.catch_warnings(
-                record=True
-            ) as ws:
-                warnings.simplefilter("always")
-                _psd_safe_pyro_mvn_sample(
-                    name="Y", loc=loc, covariance_matrix=not_psd_covar, obs=obs
-                )
-            # Check that it added the jitter.
-            self.assertGreaterEqual(
-                mock_mvn.call_args[-1]["covariance_matrix"][0, 0].item(), 1 + 1e-8
+
+class TestPyroCatchNumericalErrors(BotorchTestCase):
+    def test_pyro_catch_error(self):
+        def potential_fn(z):
+            mvn = pyro.distributions.MultivariateNormal(
+                loc=torch.zeros(2),
+                covariance_matrix=z["K"],
             )
-            # With a not-PSD covar, it should get called multiple times.
-            self.assertTrue(any("linear algebra error" in str(w.message) for w in ws))
-            # We don't catch random Value errors.
-            with mock.patch(
-                "torch.distributions.multivariate_normal.Distribution.__init__",
-                side_effect=ValueError("dummy error"),
-            ), self.assertRaisesRegex(ValueError, "dummy"):
-                _psd_safe_pyro_mvn_sample(
-                    name="Y", loc=loc, covariance_matrix=not_psd_covar, obs=obs
-                )
+            return mvn.log_prob(torch.zeros(2))
+
+        # Test base case where everything is fine
+        z = {"K": torch.eye(2)}
+        grads, val = potential_grad(potential_fn, z)
+        self.assertTrue(torch.allclose(grads["K"], -0.5 * torch.eye(2)))
+        norm_mvn = torch.distributions.Normal(0, 1)
+        self.assertTrue(torch.allclose(val, 2 * norm_mvn.log_prob(torch.zeros(1))))
+
+        # Default behavior should catch the ValueError when trying to instantiate
+        # the MVN and return NaN instead
+        z = {"K": torch.ones(2, 2)}
+        _, val = potential_grad(potential_fn, z)
+        self.assertTrue(torch.isnan(val))
+
+        # Default behavior should catch the LinAlgError when peforming a
+        # Cholesky decomposition and return NaN instead
+        def potential_fn_chol(z):
+            return torch.linalg.cholesky(z["K"])
+
+        _, val = potential_grad(potential_fn_chol, z)
+        self.assertTrue(torch.isnan(val))
+
+        # Default behavior should not catch other errors
+        def potential_fn_rterr_foo(z):
+            raise RuntimeError("foo")
+
+        with self.assertRaisesRegex(RuntimeError, "foo"):
+            potential_grad(potential_fn_rterr_foo, z)
+
+        # But once we register this specific error then it should
+        def catch_runtime_error(e):
+            return type(e) == RuntimeError and "foo" in str(e)
+
+        register_exception_handler("foo_runtime", catch_runtime_error)
+        _, val = potential_grad(potential_fn_rterr_foo, z)
+        self.assertTrue(torch.isnan(val))
+
+        # Unless the error message is different
+        def potential_fn_rterr_bar(z):
+            raise RuntimeError("bar")
+
+        with self.assertRaisesRegex(RuntimeError, "bar"):
+            potential_grad(potential_fn_rterr_bar, z)