diff --git a/rllib/agents/a3c/a3c_tf_policy.py b/rllib/agents/a3c/a3c_tf_policy.py
index a38eff247..1ede5706c 100644
--- a/rllib/agents/a3c/a3c_tf_policy.py
+++ b/rllib/agents/a3c/a3c_tf_policy.py
@@ -1,17 +1,34 @@
 """Note: Keep in sync with changes to VTraceTFPolicy."""
 
 import ray
+from ray.rllib.agents.ppo.ppo_tf_policy import ValueNetworkMixin
 from ray.rllib.policy.sample_batch import SampleBatch
-from ray.rllib.evaluation.postprocessing import compute_advantages, \
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
     Postprocessing
 from ray.rllib.policy.tf_policy_template import build_tf_policy
 from ray.rllib.policy.tf_policy import LearningRateSchedule
+from ray.rllib.utils.deprecation import deprecation_warning
 from ray.rllib.utils.framework import try_import_tf
-from ray.rllib.utils.tf_ops import explained_variance, make_tf_callable
+from ray.rllib.utils.tf_ops import explained_variance
 
 tf1, tf, tfv = try_import_tf()
 
 
+def postprocess_advantages(policy,
+                           sample_batch,
+                           other_agent_batches=None,
+                           episode=None):
+
+    # Stub serving backward compatibility.
+    deprecation_warning(
+        old="rllib.agents.a3c.a3c_tf_policy.postprocess_advantages",
+        new="rllib.evaluation.postprocessing.compute_gae_for_sample_batch",
+        error=False)
+
+    return compute_gae_for_sample_batch(policy, sample_batch,
+                                        other_agent_batches, episode)
+
+
 class A3CLoss:
     def __init__(self,
                  action_dist,
@@ -45,46 +62,10 @@ def actor_critic_loss(policy, model, dist_class, train_batch):
     return policy.loss.total_loss
 
 
-def postprocess_advantages(policy,
-                           sample_batch,
-                           other_agent_batches=None,
-                           episode=None):
-    completed = sample_batch[SampleBatch.DONES][-1]
-    if completed:
-        last_r = 0.0
-    else:
-        next_state = []
-        for i in range(policy.num_state_tensors()):
-            next_state.append(sample_batch["state_out_{}".format(i)][-1])
-        last_r = policy._value(sample_batch[SampleBatch.NEXT_OBS][-1],
-                               sample_batch[SampleBatch.ACTIONS][-1],
-                               sample_batch[SampleBatch.REWARDS][-1],
-                               *next_state)
-    return compute_advantages(
-        sample_batch, last_r, policy.config["gamma"], policy.config["lambda"],
-        policy.config["use_gae"], policy.config["use_critic"])
-
-
 def add_value_function_fetch(policy):
     return {SampleBatch.VF_PREDS: policy.model.value_function()}
 
 
-class ValueNetworkMixin:
-    def __init__(self):
-        @make_tf_callable(self.get_session())
-        def value(ob, prev_action, prev_reward, *state):
-            model_out, _ = self.model({
-                SampleBatch.CUR_OBS: tf.convert_to_tensor([ob]),
-                SampleBatch.PREV_ACTIONS: tf.convert_to_tensor([prev_action]),
-                SampleBatch.PREV_REWARDS: tf.convert_to_tensor([prev_reward]),
-                "is_training": tf.convert_to_tensor(False),
-            }, [tf.convert_to_tensor([s]) for s in state],
-                                      tf.convert_to_tensor([1]))
-            return self.model.value_function()[0]
-
-        self._value = value
-
-
 def stats(policy, train_batch):
     return {
         "cur_lr": tf.cast(policy.cur_lr, tf.float64),
@@ -115,7 +96,7 @@ def clip_gradients(policy, optimizer, loss):
 
 
 def setup_mixins(policy, obs_space, action_space, config):
-    ValueNetworkMixin.__init__(policy)
+    ValueNetworkMixin.__init__(policy, obs_space, action_space, config)
     LearningRateSchedule.__init__(policy, config["lr"], config["lr_schedule"])
 
 
@@ -126,7 +107,7 @@ A3CTFPolicy = build_tf_policy(
     stats_fn=stats,
     grad_stats_fn=grad_stats,
     gradients_fn=clip_gradients,
-    postprocess_fn=postprocess_advantages,
+    postprocess_fn=compute_gae_for_sample_batch,
     extra_action_fetches_fn=add_value_function_fetch,
     before_loss_init=setup_mixins,
     mixins=[ValueNetworkMixin, LearningRateSchedule])
diff --git a/rllib/agents/a3c/a3c_torch_policy.py b/rllib/agents/a3c/a3c_torch_policy.py
index 5eb83eb5f..603c37aab 100644
--- a/rllib/agents/a3c/a3c_torch_policy.py
+++ b/rllib/agents/a3c/a3c_torch_policy.py
@@ -1,13 +1,35 @@
+import gym
+
 import ray
-from ray.rllib.evaluation.postprocessing import compute_advantages, \
+from ray.rllib.agents.ppo.ppo_torch_policy import ValueNetworkMixin
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
     Postprocessing
+from ray.rllib.policy.policy import Policy
 from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.policy.sample_batch import SampleBatch
+from ray.rllib.utils.deprecation import deprecation_warning
 from ray.rllib.utils.framework import try_import_torch
+from ray.rllib.utils.torch_ops import apply_grad_clipping
+from ray.rllib.utils.typing import TrainerConfigDict
 
 torch, nn = try_import_torch()
 
 
+def add_advantages(policy,
+                   sample_batch,
+                   other_agent_batches=None,
+                   episode=None):
+
+    # Stub serving backward compatibility.
+    deprecation_warning(
+        old="rllib.agents.a3c.a3c_torch_policy.add_advantages",
+        new="rllib.evaluation.postprocessing.compute_gae_for_sample_batch",
+        error=False)
+
+    return compute_gae_for_sample_batch(policy, sample_batch,
+                                        other_agent_batches, episode)
+
+
 def actor_critic_loss(policy, model, dist_class, train_batch):
     logits, _ = model.from_batch(train_batch)
     values = model.value_function()
@@ -36,52 +58,27 @@ def loss_and_entropy_stats(policy, train_batch):
     }
 
 
-def add_advantages(policy,
-                   sample_batch,
-                   other_agent_batches=None,
-                   episode=None):
-
-    completed = sample_batch[SampleBatch.DONES][-1]
-    if completed:
-        last_r = 0.0
-    else:
-        last_r = policy._value(sample_batch[SampleBatch.NEXT_OBS][-1])
-
-    return compute_advantages(
-        sample_batch, last_r, policy.config["gamma"], policy.config["lambda"],
-        policy.config["use_gae"], policy.config["use_critic"])
-
-
 def model_value_predictions(policy, input_dict, state_batches, model,
                             action_dist):
     return {SampleBatch.VF_PREDS: model.value_function()}
 
 
-def apply_grad_clipping(policy, optimizer, loss):
-    info = {}
-    if policy.config["grad_clip"]:
-        for param_group in optimizer.param_groups:
-            # Make sure we only pass params with grad != None into torch
-            # clip_grad_norm_. Would fail otherwise.
-            params = list(
-                filter(lambda p: p.grad is not None, param_group["params"]))
-            if params:
-                grad_gnorm = nn.utils.clip_grad_norm_(
-                    params, policy.config["grad_clip"])
-                if isinstance(grad_gnorm, torch.Tensor):
-                    grad_gnorm = grad_gnorm.cpu().numpy()
-                info["grad_gnorm"] = grad_gnorm
-    return info
-
-
 def torch_optimizer(policy, config):
     return torch.optim.Adam(policy.model.parameters(), lr=config["lr"])
 
 
-class ValueNetworkMixin:
-    def _value(self, obs):
-        _ = self.model({"obs": torch.Tensor([obs]).to(self.device)}, [], [1])
-        return self.model.value_function()[0]
+def setup_mixins(policy: Policy, obs_space: gym.spaces.Space,
+                 action_space: gym.spaces.Space,
+                 config: TrainerConfigDict) -> None:
+    """Call all mixin classes' constructors before PPOPolicy initialization.
+
+    Args:
+        policy (Policy): The Policy object.
+        obs_space (gym.spaces.Space): The Policy's observation space.
+        action_space (gym.spaces.Space): The Policy's action space.
+        config (TrainerConfigDict): The Policy's config.
+    """
+    ValueNetworkMixin.__init__(policy, obs_space, action_space, config)
 
 
 A3CTorchPolicy = build_policy_class(
@@ -90,9 +87,10 @@ A3CTorchPolicy = build_policy_class(
     get_default_config=lambda: ray.rllib.agents.a3c.a3c.DEFAULT_CONFIG,
     loss_fn=actor_critic_loss,
     stats_fn=loss_and_entropy_stats,
-    postprocess_fn=add_advantages,
+    postprocess_fn=compute_gae_for_sample_batch,
     extra_action_out_fn=model_value_predictions,
     extra_grad_process_fn=apply_grad_clipping,
     optimizer_fn=torch_optimizer,
+    before_loss_init=setup_mixins,
     mixins=[ValueNetworkMixin],
 )
diff --git a/rllib/agents/cql/cql_torch_policy.py b/rllib/agents/cql/cql_torch_policy.py
index 14812230f..aace3e8b0 100644
--- a/rllib/agents/cql/cql_torch_policy.py
+++ b/rllib/agents/cql/cql_torch_policy.py
@@ -8,7 +8,6 @@ from typing import Dict, List, Tuple, Type, Union
 
 import ray
 import ray.experimental.tf_utils
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.sac.sac_tf_policy import postprocess_trajectory, \
     validate_spaces
 from ray.rllib.agents.sac.sac_torch_policy import _get_dist_class, stats, \
@@ -22,7 +21,8 @@ from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.utils.framework import try_import_torch
 from ray.rllib.utils.typing import LocalOptimizer, TensorType, \
     TrainerConfigDict
-from ray.rllib.utils.torch_ops import convert_to_torch_tensor
+from ray.rllib.utils.torch_ops import apply_grad_clipping, \
+    convert_to_torch_tensor
 
 torch, nn = try_import_torch()
 F = nn.functional
diff --git a/rllib/agents/ddpg/ddpg_torch_policy.py b/rllib/agents/ddpg/ddpg_torch_policy.py
index 79be4cce8..f6c73f912 100644
--- a/rllib/agents/ddpg/ddpg_torch_policy.py
+++ b/rllib/agents/ddpg/ddpg_torch_policy.py
@@ -1,7 +1,6 @@
 import logging
 
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.ddpg.ddpg_tf_policy import build_ddpg_models, \
     get_distribution_inputs_and_class, validate_spaces
 from ray.rllib.agents.dqn.dqn_tf_policy import postprocess_nstep_and_prio, \
@@ -10,7 +9,7 @@ from ray.rllib.models.torch.torch_action_dist import TorchDeterministic
 from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.utils.framework import try_import_torch
-from ray.rllib.utils.torch_ops import huber_loss, l2_loss
+from ray.rllib.utils.torch_ops import apply_grad_clipping, huber_loss, l2_loss
 
 torch, nn = try_import_torch()
 
diff --git a/rllib/agents/dqn/dqn_tf_policy.py b/rllib/agents/dqn/dqn_tf_policy.py
index d1d6d4570..874f34ba8 100644
--- a/rllib/agents/dqn/dqn_tf_policy.py
+++ b/rllib/agents/dqn/dqn_tf_policy.py
@@ -301,17 +301,11 @@ def adam_optimizer(policy: Policy, config: TrainerConfigDict
 
 def clip_gradients(policy: Policy, optimizer: "tf.keras.optimizers.Optimizer",
                    loss: TensorType) -> ModelGradients:
-    if policy.config["grad_clip"] is not None:
-        grads_and_vars = minimize_and_clip(
-            optimizer,
-            loss,
-            var_list=policy.q_func_vars,
-            clip_val=policy.config["grad_clip"])
-    else:
-        grads_and_vars = optimizer.compute_gradients(
-            loss, var_list=policy.q_func_vars)
-    grads_and_vars = [(g, v) for (g, v) in grads_and_vars if g is not None]
-    return grads_and_vars
+    return minimize_and_clip(
+        optimizer,
+        loss,
+        var_list=policy.q_func_vars,
+        clip_val=policy.config["grad_clip"])
 
 
 def build_q_stats(policy: Policy, batch) -> Dict[str, TensorType]:
diff --git a/rllib/agents/dqn/dqn_torch_policy.py b/rllib/agents/dqn/dqn_torch_policy.py
index 1ed468e1d..b6800dafa 100644
--- a/rllib/agents/dqn/dqn_torch_policy.py
+++ b/rllib/agents/dqn/dqn_torch_policy.py
@@ -4,7 +4,6 @@ from typing import Dict, List, Tuple
 
 import gym
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.dqn.dqn_tf_policy import (
     PRIO_WEIGHTS, Q_SCOPE, Q_TARGET_SCOPE, postprocess_nstep_and_prio)
 from ray.rllib.agents.dqn.dqn_torch_model import DQNTorchModel
@@ -20,9 +19,8 @@ from ray.rllib.policy.torch_policy import LearningRateSchedule
 from ray.rllib.utils.error import UnsupportedSpaceException
 from ray.rllib.utils.exploration.parameter_noise import ParameterNoise
 from ray.rllib.utils.framework import try_import_torch
-from ray.rllib.utils.torch_ops import (FLOAT_MIN, huber_loss,
-                                       reduce_mean_ignore_inf,
-                                       softmax_cross_entropy_with_logits)
+from ray.rllib.utils.torch_ops import apply_grad_clipping, FLOAT_MIN, \
+    huber_loss, reduce_mean_ignore_inf, softmax_cross_entropy_with_logits
 from ray.rllib.utils.typing import TensorType, TrainerConfigDict
 
 torch, nn = try_import_torch()
diff --git a/rllib/agents/dreamer/dreamer_torch_policy.py b/rllib/agents/dreamer/dreamer_torch_policy.py
index d23ad9c30..cc0c1e2a2 100644
--- a/rllib/agents/dreamer/dreamer_torch_policy.py
+++ b/rllib/agents/dreamer/dreamer_torch_policy.py
@@ -1,11 +1,11 @@
 import logging
 
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.dreamer.utils import FreezeParameters
 from ray.rllib.models.catalog import ModelCatalog
 from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.utils.framework import try_import_torch
+from ray.rllib.utils.torch_ops import apply_grad_clipping
 
 torch, nn = try_import_torch()
 if torch:
diff --git a/rllib/agents/impala/impala.py b/rllib/agents/impala/impala.py
index 0bcddf4f3..580cf1ad3 100644
--- a/rllib/agents/impala/impala.py
+++ b/rllib/agents/impala/impala.py
@@ -1,7 +1,6 @@
 import logging
 
 import ray
-from ray.rllib.agents.a3c.a3c_tf_policy import A3CTFPolicy
 from ray.rllib.agents.impala.vtrace_tf_policy import VTraceTFPolicy
 from ray.rllib.agents.trainer import Trainer, with_common_config
 from ray.rllib.agents.trainer_template import build_trainer
@@ -160,6 +159,7 @@ def get_policy_class(config):
         if config["vtrace"]:
             return VTraceTFPolicy
         else:
+            from ray.rllib.agents.a3c.a3c_tf_policy import A3CTFPolicy
             return A3CTFPolicy
 
 
diff --git a/rllib/agents/impala/vtrace_torch_policy.py b/rllib/agents/impala/vtrace_torch_policy.py
index c6b8c2634..7fc4398dd 100644
--- a/rllib/agents/impala/vtrace_torch_policy.py
+++ b/rllib/agents/impala/vtrace_torch_policy.py
@@ -3,7 +3,6 @@ import logging
 import numpy as np
 
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 import ray.rllib.agents.impala.vtrace_torch as vtrace
 from ray.rllib.models.torch.torch_action_dist import TorchCategorical
 from ray.rllib.policy.policy_template import build_policy_class
@@ -11,8 +10,8 @@ from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.policy.torch_policy import LearningRateSchedule, \
     EntropyCoeffSchedule
 from ray.rllib.utils.framework import try_import_torch
-from ray.rllib.utils.torch_ops import explained_variance, global_norm, \
-    sequence_mask
+from ray.rllib.utils.torch_ops import apply_grad_clipping, \
+    explained_variance, global_norm, sequence_mask
 
 torch, nn = try_import_torch()
 
diff --git a/rllib/agents/maml/maml_tf_policy.py b/rllib/agents/maml/maml_tf_policy.py
index b9e4d0775..d5fa2568f 100644
--- a/rllib/agents/maml/maml_tf_policy.py
+++ b/rllib/agents/maml/maml_tf_policy.py
@@ -1,10 +1,10 @@
 import logging
 
 import ray
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae, \
-    vf_preds_fetches, compute_and_clip_gradients, setup_config, \
-    ValueNetworkMixin
-from ray.rllib.evaluation.postprocessing import Postprocessing
+from ray.rllib.agents.ppo.ppo_tf_policy import vf_preds_fetches, \
+    compute_and_clip_gradients, setup_config, ValueNetworkMixin
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
+    Postprocessing
 from ray.rllib.models.utils import get_activation_fn
 from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.policy.tf_policy_template import build_tf_policy
@@ -422,7 +422,7 @@ MAMLTFPolicy = build_tf_policy(
     stats_fn=maml_stats,
     optimizer_fn=maml_optimizer_fn,
     extra_action_fetches_fn=vf_preds_fetches,
-    postprocess_fn=postprocess_ppo_gae,
+    postprocess_fn=compute_gae_for_sample_batch,
     gradients_fn=compute_and_clip_gradients,
     before_init=setup_config,
     before_loss_init=setup_mixins,
diff --git a/rllib/agents/maml/maml_torch_policy.py b/rllib/agents/maml/maml_torch_policy.py
index 478d95ba6..2e0e1e208 100644
--- a/rllib/agents/maml/maml_torch_policy.py
+++ b/rllib/agents/maml/maml_torch_policy.py
@@ -1,15 +1,15 @@
 import logging
 
 import ray
-from ray.rllib.evaluation.postprocessing import Postprocessing
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
+    Postprocessing
 from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.policy.sample_batch import SampleBatch
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae, \
-    setup_config
+from ray.rllib.agents.ppo.ppo_tf_policy import setup_config
 from ray.rllib.agents.ppo.ppo_torch_policy import vf_preds_fetches, \
     ValueNetworkMixin
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.utils.framework import try_import_torch
+from ray.rllib.utils.torch_ops import apply_grad_clipping
 
 torch, nn = try_import_torch()
 
@@ -355,7 +355,7 @@ MAMLTorchPolicy = build_policy_class(
     stats_fn=maml_stats,
     optimizer_fn=maml_optimizer_fn,
     extra_action_out_fn=vf_preds_fetches,
-    postprocess_fn=postprocess_ppo_gae,
+    postprocess_fn=compute_gae_for_sample_batch,
     extra_grad_process_fn=apply_grad_clipping,
     before_init=setup_config,
     after_init=setup_mixins,
diff --git a/rllib/agents/mbmpo/mbmpo_torch_policy.py b/rllib/agents/mbmpo/mbmpo_torch_policy.py
index f43d06ebe..06e65042e 100644
--- a/rllib/agents/mbmpo/mbmpo_torch_policy.py
+++ b/rllib/agents/mbmpo/mbmpo_torch_policy.py
@@ -3,18 +3,18 @@ import logging
 from typing import Tuple, Type
 
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.maml.maml_torch_policy import setup_mixins, \
     maml_loss, maml_stats, maml_optimizer_fn, KLCoeffMixin
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae, \
-    setup_config
+from ray.rllib.agents.ppo.ppo_tf_policy import setup_config
 from ray.rllib.agents.ppo.ppo_torch_policy import vf_preds_fetches
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch
 from ray.rllib.models.catalog import ModelCatalog
 from ray.rllib.models.modelv2 import ModelV2
 from ray.rllib.models.torch.torch_action_dist import TorchDistributionWrapper
 from ray.rllib.policy.policy import Policy
 from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.utils.framework import try_import_torch
+from ray.rllib.utils.torch_ops import apply_grad_clipping
 from ray.rllib.utils.typing import TrainerConfigDict
 
 torch, nn = try_import_torch()
@@ -85,7 +85,7 @@ MBMPOTorchPolicy = build_policy_class(
     stats_fn=maml_stats,
     optimizer_fn=maml_optimizer_fn,
     extra_action_out_fn=vf_preds_fetches,
-    postprocess_fn=postprocess_ppo_gae,
+    postprocess_fn=compute_gae_for_sample_batch,
     extra_grad_process_fn=apply_grad_clipping,
     before_init=setup_config,
     after_init=setup_mixins,
diff --git a/rllib/agents/ppo/appo_tf_policy.py b/rllib/agents/ppo/appo_tf_policy.py
index c45cfb0ba..96d677e61 100644
--- a/rllib/agents/ppo/appo_tf_policy.py
+++ b/rllib/agents/ppo/appo_tf_policy.py
@@ -13,9 +13,9 @@ from typing import Dict, List, Optional, Type, Union
 from ray.rllib.agents.impala import vtrace_tf as vtrace
 from ray.rllib.agents.impala.vtrace_tf_policy import _make_time_major, \
     clip_gradients, choose_optimizer
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae
 from ray.rllib.evaluation.episode import MultiAgentEpisode
-from ray.rllib.evaluation.postprocessing import Postprocessing
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
+    Postprocessing
 from ray.rllib.models.tf.tf_action_dist import Categorical
 from ray.rllib.policy.policy import Policy
 from ray.rllib.policy.sample_batch import SampleBatch
@@ -338,8 +338,8 @@ def postprocess_trajectory(
         SampleBatch: The postprocessed, modified SampleBatch (or a new one).
     """
     if not policy.config["vtrace"]:
-        sample_batch = postprocess_ppo_gae(policy, sample_batch,
-                                           other_agent_batches, episode)
+        sample_batch = compute_gae_for_sample_batch(
+            policy, sample_batch, other_agent_batches, episode)
 
     # TODO: (sven) remove this del once we have trajectory view API fully in
     #  place.
diff --git a/rllib/agents/ppo/appo_torch_policy.py b/rllib/agents/ppo/appo_torch_policy.py
index 461886dbe..81d748331 100644
--- a/rllib/agents/ppo/appo_torch_policy.py
+++ b/rllib/agents/ppo/appo_torch_policy.py
@@ -10,7 +10,6 @@ import numpy as np
 import logging
 from typing import Type
 
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 import ray.rllib.agents.impala.vtrace_torch as vtrace
 from ray.rllib.agents.impala.vtrace_torch_policy import make_time_major, \
     choose_optimizer
@@ -27,8 +26,8 @@ from ray.rllib.policy.policy_template import build_policy_class
 from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.policy.torch_policy import LearningRateSchedule
 from ray.rllib.utils.framework import try_import_torch
-from ray.rllib.utils.torch_ops import explained_variance, global_norm, \
-    sequence_mask
+from ray.rllib.utils.torch_ops import apply_grad_clipping, explained_variance,\
+    global_norm, sequence_mask
 from ray.rllib.utils.typing import TensorType, TrainerConfigDict
 
 torch, nn = try_import_torch()
diff --git a/rllib/agents/ppo/ppo_tf_policy.py b/rllib/agents/ppo/ppo_tf_policy.py
index 1a8f0be71..57874ba29 100644
--- a/rllib/agents/ppo/ppo_tf_policy.py
+++ b/rllib/agents/ppo/ppo_tf_policy.py
@@ -8,7 +8,7 @@ from typing import Dict, List, Optional, Type, Union
 
 import ray
 from ray.rllib.evaluation.episode import MultiAgentEpisode
-from ray.rllib.evaluation.postprocessing import compute_advantages, \
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
     Postprocessing
 from ray.rllib.models.modelv2 import ModelV2
 from ray.rllib.models.tf.tf_action_dist import TFActionDistribution
@@ -160,71 +160,6 @@ def vf_preds_fetches(policy: Policy) -> Dict[str, TensorType]:
     }
 
 
-def postprocess_ppo_gae(
-        policy: Policy,
-        sample_batch: SampleBatch,
-        other_agent_batches: Optional[Dict[AgentID, SampleBatch]] = None,
-        episode: Optional[MultiAgentEpisode] = None) -> SampleBatch:
-    """Postprocesses a trajectory and returns the processed trajectory.
-
-    The trajectory contains only data from one episode and from one agent.
-    - If  `config.batch_mode=truncate_episodes` (default), sample_batch may
-    contain a truncated (at-the-end) episode, in case the
-    `config.rollout_fragment_length` was reached by the sampler.
-    - If `config.batch_mode=complete_episodes`, sample_batch will contain
-    exactly one episode (no matter how long).
-    New columns can be added to sample_batch and existing ones may be altered.
-
-    Args:
-        policy (Policy): The Policy used to generate the trajectory
-            (`sample_batch`)
-        sample_batch (SampleBatch): The SampleBatch to postprocess.
-        other_agent_batches (Optional[Dict[PolicyID, SampleBatch]]): Optional
-            dict of AgentIDs mapping to other agents' trajectory data (from the
-            same episode). NOTE: The other agents use the same policy.
-        episode (Optional[MultiAgentEpisode]): Optional multi-agent episode
-            object in which the agents operated.
-
-    Returns:
-        SampleBatch: The postprocessed, modified SampleBatch (or a new one).
-    """
-
-    # Trajectory is actually complete -> last r=0.0.
-    if sample_batch[SampleBatch.DONES][-1]:
-        last_r = 0.0
-    # Trajectory has been truncated -> last r=VF estimate of last obs.
-    else:
-        # Input dict is provided to us automatically via the Model's
-        # requirements. It's a single-timestep (last one in trajectory)
-        # input_dict.
-        if policy.config["_use_trajectory_view_api"]:
-            # Create an input dict according to the Model's requirements.
-            input_dict = policy.model.get_input_dict(
-                sample_batch, index="last")
-            last_r = policy._value(**input_dict)
-        # TODO: (sven) Remove once trajectory view API is all-algo default.
-        else:
-            next_state = []
-            for i in range(policy.num_state_tensors()):
-                next_state.append(sample_batch["state_out_{}".format(i)][-1])
-            last_r = policy._value(sample_batch[SampleBatch.NEXT_OBS][-1],
-                                   sample_batch[SampleBatch.ACTIONS][-1],
-                                   sample_batch[SampleBatch.REWARDS][-1],
-                                   *next_state)
-
-    # Adds the policy logits, VF preds, and advantages to the batch,
-    # using GAE ("generalized advantage estimation") or not.
-    batch = compute_advantages(
-        sample_batch,
-        last_r,
-        policy.config["gamma"],
-        policy.config["lambda"],
-        use_gae=policy.config["use_gae"],
-        use_critic=policy.config.get("use_critic", True))
-
-    return batch
-
-
 def compute_and_clip_gradients(policy: Policy, optimizer: LocalOptimizer,
                                loss: TensorType) -> ModelGradients:
     """Gradients computing function (from loss tensor, using local optimizer).
@@ -392,13 +327,29 @@ def setup_mixins(policy: Policy, obs_space: gym.spaces.Space,
     LearningRateSchedule.__init__(policy, config["lr"], config["lr_schedule"])
 
 
+def postprocess_ppo_gae(
+        policy: Policy,
+        sample_batch: SampleBatch,
+        other_agent_batches: Optional[Dict[AgentID, SampleBatch]] = None,
+        episode: Optional[MultiAgentEpisode] = None) -> SampleBatch:
+
+    # Stub serving backward compatibility.
+    deprecation_warning(
+        old="rllib.agents.ppo.ppo_tf_policy.postprocess_ppo_gae",
+        new="rllib.evaluation.postprocessing.compute_gae_for_sample_batch",
+        error=False)
+
+    return compute_gae_for_sample_batch(policy, sample_batch,
+                                        other_agent_batches, episode)
+
+
 # Build a child class of `DynamicTFPolicy`, given the custom functions defined
 # above.
 PPOTFPolicy = build_tf_policy(
     name="PPOTFPolicy",
     loss_fn=ppo_surrogate_loss,
     get_default_config=lambda: ray.rllib.agents.ppo.ppo.DEFAULT_CONFIG,
-    postprocess_fn=postprocess_ppo_gae,
+    postprocess_fn=compute_gae_for_sample_batch,
     stats_fn=kl_and_loss_stats,
     gradients_fn=compute_and_clip_gradients,
     extra_action_fetches_fn=vf_preds_fetches,
diff --git a/rllib/agents/ppo/ppo_torch_policy.py b/rllib/agents/ppo/ppo_torch_policy.py
index d73f53666..8bd07824b 100644
--- a/rllib/agents/ppo/ppo_torch_policy.py
+++ b/rllib/agents/ppo/ppo_torch_policy.py
@@ -7,10 +7,9 @@ import numpy as np
 from typing import Dict, List, Type, Union
 
 import ray
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae, \
-    setup_config
-from ray.rllib.evaluation.postprocessing import Postprocessing
+from ray.rllib.agents.ppo.ppo_tf_policy import setup_config
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
+    Postprocessing
 from ray.rllib.models.modelv2 import ModelV2
 from ray.rllib.models.torch.torch_action_dist import TorchDistributionWrapper
 from ray.rllib.policy.policy import Policy
@@ -19,8 +18,8 @@ from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.policy.torch_policy import EntropyCoeffSchedule, \
     LearningRateSchedule
 from ray.rllib.utils.framework import try_import_torch
-from ray.rllib.utils.torch_ops import convert_to_torch_tensor, \
-    explained_variance, sequence_mask
+from ray.rllib.utils.torch_ops import apply_grad_clipping, \
+    convert_to_torch_tensor, explained_variance, sequence_mask
 from ray.rllib.utils.typing import TensorType, TrainerConfigDict
 
 torch, nn = try_import_torch()
@@ -279,7 +278,7 @@ PPOTorchPolicy = build_policy_class(
     loss_fn=ppo_surrogate_loss,
     stats_fn=kl_and_loss_stats,
     extra_action_out_fn=vf_preds_fetches,
-    postprocess_fn=postprocess_ppo_gae,
+    postprocess_fn=compute_gae_for_sample_batch,
     extra_grad_process_fn=apply_grad_clipping,
     before_init=setup_config,
     before_loss_init=setup_mixins,
diff --git a/rllib/agents/ppo/tests/test_ppo.py b/rllib/agents/ppo/tests/test_ppo.py
index cb304c57e..de0bc90f6 100644
--- a/rllib/agents/ppo/tests/test_ppo.py
+++ b/rllib/agents/ppo/tests/test_ppo.py
@@ -5,11 +5,12 @@ import unittest
 import ray
 from ray.rllib.agents.callbacks import DefaultCallbacks
 import ray.rllib.agents.ppo as ppo
-from ray.rllib.agents.ppo.ppo_tf_policy import postprocess_ppo_gae as \
-    postprocess_ppo_gae_tf, ppo_surrogate_loss as ppo_surrogate_loss_tf
-from ray.rllib.agents.ppo.ppo_torch_policy import postprocess_ppo_gae as \
-    postprocess_ppo_gae_torch, ppo_surrogate_loss as ppo_surrogate_loss_torch
-from ray.rllib.evaluation.postprocessing import Postprocessing
+from ray.rllib.agents.ppo.ppo_tf_policy import ppo_surrogate_loss as \
+    ppo_surrogate_loss_tf
+from ray.rllib.agents.ppo.ppo_torch_policy import ppo_surrogate_loss as \
+    ppo_surrogate_loss_torch
+from ray.rllib.evaluation.postprocessing import compute_gae_for_sample_batch, \
+    Postprocessing
 from ray.rllib.models.tf.tf_action_dist import Categorical
 from ray.rllib.models.torch.torch_modelv2 import TorchModelV2
 from ray.rllib.models.torch.torch_action_dist import TorchCategorical
@@ -212,11 +213,8 @@ class TestPPO(unittest.TestCase):
             # Check the variable is initially zero.
             init_std = get_value()
             assert init_std == 0.0, init_std
-
-            if fw in ["tf2", "tf", "tfe"]:
-                batch = postprocess_ppo_gae_tf(policy, FAKE_BATCH.copy())
-            else:
-                batch = postprocess_ppo_gae_torch(policy, FAKE_BATCH.copy())
+            batch = compute_gae_for_sample_batch(policy, FAKE_BATCH.copy())
+            if fw == "torch":
                 batch = policy._lazy_tensor_dict(batch)
             policy.learn_on_batch(batch)
 
@@ -255,11 +253,9 @@ class TestPPO(unittest.TestCase):
             # to train_batch dict.
             # A = [0.99^2 * 0.5 + 0.99 * -1.0 + 1.0, 0.99 * 0.5 - 1.0, 0.5] =
             # [0.50005, -0.505, 0.5]
-            if fw in ["tf2", "tf", "tfe"]:
-                train_batch = postprocess_ppo_gae_tf(policy, FAKE_BATCH.copy())
-            else:
-                train_batch = postprocess_ppo_gae_torch(
-                    policy, FAKE_BATCH.copy())
+            train_batch = compute_gae_for_sample_batch(policy,
+                                                       FAKE_BATCH.copy())
+            if fw == "torch":
                 train_batch = policy._lazy_tensor_dict(train_batch)
 
             # Check Advantage values.
diff --git a/rllib/agents/sac/sac.py b/rllib/agents/sac/sac.py
index daf66f88a..5c476248c 100644
--- a/rllib/agents/sac/sac.py
+++ b/rllib/agents/sac/sac.py
@@ -73,8 +73,7 @@ DEFAULT_CONFIG = with_common_config({
     "timesteps_per_iteration": 100,
 
     # === Replay buffer ===
-    # Size of the replay buffer. Note that if async_updates is set, then
-    # each worker will have a replay buffer of this size.
+    # Size of the replay buffer (in time steps).
     "buffer_size": int(1e6),
     # If True prioritized replay buffer will be used.
     "prioritized_replay": False,
@@ -104,9 +103,7 @@ DEFAULT_CONFIG = with_common_config({
     # Update the replay buffer with this many samples at once. Note that this
     # setting applies per-worker if num_workers > 1.
     "rollout_fragment_length": 1,
-    # Size of a batched sampled from replay buffer for training. Note that
-    # if async_updates is set, then each worker returns gradients for a
-    # batch of this size.
+    # Size of a batched sampled from replay buffer for training.
     "train_batch_size": 256,
     # Update the target network every `target_network_update_freq` steps.
     "target_network_update_freq": 0,
diff --git a/rllib/agents/sac/sac_torch_policy.py b/rllib/agents/sac/sac_torch_policy.py
index 49bc65557..d000e1839 100644
--- a/rllib/agents/sac/sac_torch_policy.py
+++ b/rllib/agents/sac/sac_torch_policy.py
@@ -9,7 +9,6 @@ from typing import Dict, List, Optional, Tuple, Type, Union
 
 import ray
 import ray.experimental.tf_utils
-from ray.rllib.agents.a3c.a3c_torch_policy import apply_grad_clipping
 from ray.rllib.agents.sac.sac_tf_policy import build_sac_model, \
     postprocess_trajectory, validate_spaces
 from ray.rllib.agents.dqn.dqn_tf_policy import PRIO_WEIGHTS
@@ -23,7 +22,7 @@ from ray.rllib.models.torch.torch_action_dist import (
     TorchCategorical, TorchSquashedGaussian, TorchDiagGaussian, TorchBeta)
 from ray.rllib.utils.framework import try_import_torch
 from ray.rllib.utils.spaces.simplex import Simplex
-from ray.rllib.utils.torch_ops import huber_loss
+from ray.rllib.utils.torch_ops import apply_grad_clipping, huber_loss
 from ray.rllib.utils.typing import LocalOptimizer, TensorType, \
     TrainerConfigDict
 
diff --git a/rllib/contrib/maddpg/maddpg_policy.py b/rllib/contrib/maddpg/maddpg_policy.py
index 913c3f530..6615498ec 100644
--- a/rllib/contrib/maddpg/maddpg_policy.py
+++ b/rllib/contrib/maddpg/maddpg_policy.py
@@ -265,17 +265,11 @@ class MADDPGTFPolicy(MADDPGPostprocessing, TFPolicy):
 
     @override(TFPolicy)
     def gradients(self, optimizer, loss):
-        if self.config["grad_norm_clipping"] is not None:
-            self.gvs = {
-                k: minimize_and_clip(optimizer, self.losses[k], self.vars[k],
-                                     self.config["grad_norm_clipping"])
-                for k, optimizer in self.optimizers.items()
-            }
-        else:
-            self.gvs = {
-                k: optimizer.compute_gradients(self.losses[k], self.vars[k])
-                for k, optimizer in self.optimizers.items()
-            }
+        self.gvs = {
+            k: minimize_and_clip(optimizer, self.losses[k], self.vars[k],
+                                 self.config["grad_norm_clipping"])
+            for k, optimizer in self.optimizers.items()
+        }
         return self.gvs["critic"] + self.gvs["actor"]
 
     @override(TFPolicy)
diff --git a/rllib/evaluation/postprocessing.py b/rllib/evaluation/postprocessing.py
index 0cb25d5c7..7d1801cf6 100644
--- a/rllib/evaluation/postprocessing.py
+++ b/rllib/evaluation/postprocessing.py
@@ -1,22 +1,12 @@
 import numpy as np
 import scipy.signal
+from typing import Dict, Optional
+
+from ray.rllib.evaluation.episode import MultiAgentEpisode
+from ray.rllib.policy.policy import Policy
 from ray.rllib.policy.sample_batch import SampleBatch
 from ray.rllib.utils.annotations import DeveloperAPI
-
-
-def discount_cumsum(x: np.ndarray, gamma: float) -> float:
-    """Calculates the discounted cumulative sum over a reward sequence `x`.
-
-    y[t] - discount*y[t+1] = x[t]
-    reversed(y)[t] - discount*reversed(y)[t-1] = reversed(x)[t]
-
-    Args:
-        gamma (float): The discount factor gamma.
-
-    Returns:
-        float: The discounted cumulative sum over the reward sequence `x`.
-    """
-    return scipy.signal.lfilter([1], [1, float(-gamma)], x[::-1], axis=0)[::-1]
+from ray.rllib.utils.typing import AgentID
 
 
 class Postprocessing:
@@ -89,3 +79,83 @@ def compute_advantages(rollout: SampleBatch,
         Postprocessing.ADVANTAGES].astype(np.float32)
 
     return rollout
+
+
+def compute_gae_for_sample_batch(
+        policy: Policy,
+        sample_batch: SampleBatch,
+        other_agent_batches: Optional[Dict[AgentID, SampleBatch]] = None,
+        episode: Optional[MultiAgentEpisode] = None) -> SampleBatch:
+    """Adds GAE (generalized advantage estimations) to a trajectory.
+
+    The trajectory contains only data from one episode and from one agent.
+    - If  `config.batch_mode=truncate_episodes` (default), sample_batch may
+    contain a truncated (at-the-end) episode, in case the
+    `config.rollout_fragment_length` was reached by the sampler.
+    - If `config.batch_mode=complete_episodes`, sample_batch will contain
+    exactly one episode (no matter how long).
+    New columns can be added to sample_batch and existing ones may be altered.
+
+    Args:
+        policy (Policy): The Policy used to generate the trajectory
+            (`sample_batch`)
+        sample_batch (SampleBatch): The SampleBatch to postprocess.
+        other_agent_batches (Optional[Dict[PolicyID, SampleBatch]]): Optional
+            dict of AgentIDs mapping to other agents' trajectory data (from the
+            same episode). NOTE: The other agents use the same policy.
+        episode (Optional[MultiAgentEpisode]): Optional multi-agent episode
+            object in which the agents operated.
+
+    Returns:
+        SampleBatch: The postprocessed, modified SampleBatch (or a new one).
+    """
+
+    # Trajectory is actually complete -> last r=0.0.
+    if sample_batch[SampleBatch.DONES][-1]:
+        last_r = 0.0
+    # Trajectory has been truncated -> last r=VF estimate of last obs.
+    else:
+        # Input dict is provided to us automatically via the Model's
+        # requirements. It's a single-timestep (last one in trajectory)
+        # input_dict.
+        if policy.config.get("_use_trajectory_view_api"):
+            # Create an input dict according to the Model's requirements.
+            input_dict = policy.model.get_input_dict(
+                sample_batch, index="last")
+            last_r = policy._value(**input_dict)
+        # TODO: (sven) Remove once trajectory view API is all-algo default.
+        else:
+            next_state = []
+            for i in range(policy.num_state_tensors()):
+                next_state.append(sample_batch["state_out_{}".format(i)][-1])
+            last_r = policy._value(sample_batch[SampleBatch.NEXT_OBS][-1],
+                                   sample_batch[SampleBatch.ACTIONS][-1],
+                                   sample_batch[SampleBatch.REWARDS][-1],
+                                   *next_state)
+
+    # Adds the policy logits, VF preds, and advantages to the batch,
+    # using GAE ("generalized advantage estimation") or not.
+    batch = compute_advantages(
+        sample_batch,
+        last_r,
+        policy.config["gamma"],
+        policy.config["lambda"],
+        use_gae=policy.config["use_gae"],
+        use_critic=policy.config.get("use_critic", True))
+
+    return batch
+
+
+def discount_cumsum(x: np.ndarray, gamma: float) -> float:
+    """Calculates the discounted cumulative sum over a reward sequence `x`.
+
+    y[t] - discount*y[t+1] = x[t]
+    reversed(y)[t] - discount*reversed(y)[t-1] = reversed(x)[t]
+
+    Args:
+        gamma (float): The discount factor gamma.
+
+    Returns:
+        float: The discounted cumulative sum over the reward sequence `x`.
+    """
+    return scipy.signal.lfilter([1], [1, float(-gamma)], x[::-1], axis=0)[::-1]
diff --git a/rllib/tuned_examples/sac/mspacman-sac.yaml b/rllib/tuned_examples/sac/mspacman-sac.yaml
index c47e384db..50883b114 100644
--- a/rllib/tuned_examples/sac/mspacman-sac.yaml
+++ b/rllib/tuned_examples/sac/mspacman-sac.yaml
@@ -14,11 +14,11 @@ mspacman-sac-tf:
         # state-preprocessor=Our default Atari Conv2D-net.
         use_state_preprocessor: true
         Q_model:
-            hidden_activation: relu
-            hidden_layer_sizes: [512]
+            fcnet_hiddens: [512]
+            fcnet_activation: relu
         policy_model:
-            hidden_activation: relu
-            hidden_layer_sizes: [512]
+            fcnet_hiddens: [512]
+            fcnet_activation: relu
         # Do hard syncs.
         # Soft-syncs seem to work less reliably for discrete action spaces.
         tau: 1.0
diff --git a/rllib/utils/tf_ops.py b/rllib/utils/tf_ops.py
index f74926aaa..5b75bc5e1 100644
--- a/rllib/utils/tf_ops.py
+++ b/rllib/utils/tf_ops.py
@@ -92,7 +92,7 @@ def minimize_and_clip(optimizer, objective, var_list, clip_val=10.0):
     variable is clipped to `clip_val`
     """
     # Accidentally passing values < 0.0 will break all gradients.
-    assert clip_val > 0.0, clip_val
+    assert clip_val is None or clip_val > 0.0, clip_val
 
     if tf.executing_eagerly():
         tape = optimizer.tape
@@ -102,10 +102,8 @@ def minimize_and_clip(optimizer, objective, var_list, clip_val=10.0):
         grads_and_vars = optimizer.compute_gradients(
             objective, var_list=var_list)
 
-    for i, (grad, var) in enumerate(grads_and_vars):
-        if grad is not None:
-            grads_and_vars[i] = (tf.clip_by_norm(grad, clip_val), var)
-    return grads_and_vars
+    return [(tf.clip_by_norm(g, clip_val) if clip_val is not None else g, v)
+            for (g, v) in grads_and_vars if g is not None]
 
 
 def make_tf_callable(session_or_none, dynamic_shape=False):
diff --git a/rllib/utils/torch_ops.py b/rllib/utils/torch_ops.py
index ce6c86a16..487b8c246 100644
--- a/rllib/utils/torch_ops.py
+++ b/rllib/utils/torch_ops.py
@@ -14,6 +14,30 @@ FLOAT_MIN = -3.4e38
 FLOAT_MAX = 3.4e38
 
 
+def apply_grad_clipping(policy, optimizer, loss):
+    """Applies gradient clipping to already computed grads inside `optimizer`.
+
+    Args:
+        policy (TorchPolicy): The TorchPolicy, which calculated `loss`.
+        optimizer (torch.optim.Optimizer): A local torch optimizer object.
+        loss (torch.Tensor): The torch loss tensor.
+    """
+    info = {}
+    if policy.config["grad_clip"]:
+        for param_group in optimizer.param_groups:
+            # Make sure we only pass params with grad != None into torch
+            # clip_grad_norm_. Would fail otherwise.
+            params = list(
+                filter(lambda p: p.grad is not None, param_group["params"]))
+            if params:
+                grad_gnorm = nn.utils.clip_grad_norm_(
+                    params, policy.config["grad_clip"])
+                if isinstance(grad_gnorm, torch.Tensor):
+                    grad_gnorm = grad_gnorm.cpu().numpy()
+                info["grad_gnorm"] = grad_gnorm
+    return info
+
+
 def atanh(x):
     return 0.5 * torch.log((1 + x) / (1 - x))