comment about race-condition

Author: ryanwinchester

lib/ecto/uuid.ex

@@ -285,6 +285,8 @@ defmodule Ecto.UUID do
   defp next_ascending(time_unit) when time_unit in [:millisecond, :nanosecond] do
     timestamp_ref =
       with nil <- :persistent_term.get({__MODULE__, time_unit}, nil) do
+        # There is a small chance of a race-condition with this
+        # lazy-initialization of the persistent_term.
         timestamp_ref = :atomics.new(1, signed: false)
         :ok = :persistent_term.put({__MODULE__, time_unit}, timestamp_ref)
         timestamp_ref