[RLlib] MetricsLogger cleanup throughput logic.

rllib/utils/metrics/metrics_logger.py

@@ -30,8 +30,8 @@ class MetricsLogger:
     - Reducing these collected values using a user specified reduction method (for
     example "min" or "mean") and other settings controlling the reduction and internal
     data, such as sliding windows or EMA coefficients.
-    - Resetting the logged values after a `reduce()` call in order to make space for
-    new values to be logged.
+    - Optionally clearing all logged values after a `reduce()` call to make space for
+    new data.
 
     .. testcode::
 
@@ -335,7 +335,8 @@ def log_value(
                 object under the logged key then keeps track of the time passed
                 between two consecutive calls to `reduce()` and update its throughput
                 estimate. The current throughput estimate of a key can be obtained
-                through: `MetricsLogger.peek([some key], throughput=True)`.
+                through: peeked_value, throuthput_per_sec =
+                <MetricsLogger>.peek([key], throughput=True).
         """
         # No reduction (continue appending to list) AND no window.
         # -> We'll force-reset our values upon `reduce()`.
@@ -701,14 +702,9 @@ def log_time(
         window: Optional[Union[int, float]] = None,
         ema_coeff: Optional[float] = None,
         clear_on_reduce: bool = False,
-        key_for_throughput: Optional[Union[str, Tuple[str, ...]]] = None,
-        key_for_unit_count: Optional[Union[str, Tuple[str, ...]]] = None,
     ) -> Stats:
         """Measures and logs a time delta value under `key` when used with a with-block.
 
-        Additionally, measures and logs the throughput for the timed code, iff
-        `key_for_throughput` and `key_for_unit_count` are provided.
-
         .. testcode::
 
             import time
@@ -769,32 +765,13 @@ def log_time(
             clear_on_reduce = True
 
         if not self._key_in_stats(key):
-            measure_throughput = None
-            if key_for_unit_count is not None:
-                measure_throughput = True
-                key_for_throughput = key_for_throughput or (key + "_throughput_per_s")
-
             self._set_key(
                 key,
                 Stats(
                     reduce=reduce,
                     window=window,
                     ema_coeff=ema_coeff,
                     clear_on_reduce=clear_on_reduce,
-                    on_exit=(
-                        lambda time_delta_s, kt=key_for_throughput, ku=key_for_unit_count, r=reduce, w=window, e=ema_coeff, c=clear_on_reduce: (  # noqa
-                            self.log_value(
-                                kt,
-                                value=self.peek(ku) / time_delta_s,
-                                reduce=r,
-                                window=w,
-                                ema_coeff=e,
-                                clear_on_reduce=c,
-                            )
-                        )
-                    )
-                    if measure_throughput
-                    else None,
                 ),
             )
 
@@ -933,7 +910,9 @@ def _reduce(path, stats):
 
         try:
             with self._threading_lock:
-                assert not self.tensor_mode
+                assert (
+                    not self.tensor_mode
+                ), "Can't reduce if `self.tensor_mode` is True!"
                 reduced = copy.deepcopy(
                     tree.map_structure_with_path(_reduce, stats_to_return)
                 )
@@ -1048,7 +1027,8 @@ def set_value(
                 object under the logged key then keeps track of the time passed
                 between two consecutive calls to `reduce()` and update its throughput
                 estimate. The current throughput estimate of a key can be obtained
-                through: `MetricsLogger.peek([some key], throughput=True)`.
+                through: peeked_value, throuthput_per_sec =
+                <MetricsLogger>.peek([key], throughput=True).
         """
         # Key already in self -> Erase internal values list with [`value`].
         if self._key_in_stats(key):

rllib/utils/metrics/stats.py

@@ -175,13 +175,15 @@ def __init__(
                 to True is useful for cases, in which the internal values list would
                 otherwise grow indefinitely, for example if reduce is None and there
                 is no `window` provided.
-            with_throughput: Whether to track a throughput estimate together with this
+            throughput: If True, track a throughput estimate together with this
                 Stats. This is only supported for `reduce=sum` and
                 `clear_on_reduce=False` metrics (aka. "lifetime counts"). The `Stats`
                 then keeps track of the time passed between two consecutive calls to
                 `reduce()` and update its throughput estimate. The current throughput
                 estimate of a key can be obtained through:
-                `Stats.peek([some key], throughput=True)`.
+                `peeked_val, throughput_per_sec = Stats.peek([key], throughput=True)`.
+                If a float, track throughput and also set current throughput estimate
+                to the given value.
         """
         # Thus far, we only support mean, max, min, and sum.
         if reduce not in [None, "mean", "min", "max", "sum"]:
@@ -318,9 +320,10 @@ class for details on the reduction logic applied to the values list, based on
             # Take the delta between the new (upcoming) reduced value and the most
             # recently reduced value (one `reduce()` call ago).
             delta_sum = reduced - self._hist[-1]
-            assert delta_sum >= 0
             time_now = time.perf_counter()
-            if self._throughput_last_time == -1:
+            # `delta_sum` may be < 0.0 if user overrides a metric through
+            # `.set_value()`.
+            if self._throughput_last_time == -1 or delta_sum < 0.0:
                 self._throughput = np.nan
             else:
                 delta_time = time_now - self._throughput_last_time