Merge pull request #24897 from maclover7/jm-fix-24844

Followup to #24844

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -909,6 +909,8 @@ def remove_connection(spec_name)
       # to optimise for.
       def retrieve_connection_pool(spec_name)
         owner_to_pool.fetch(spec_name) do
+          # Check if a connection was previously established in an ancestor process,
+          # which may have been forked.
           if ancestor_pool = pool_from_any_process_for(spec_name)
             # A connection was established in an ancestor process that must have
             # subsequently forked. We can't reuse the connection, but we can copy

activerecord/lib/active_record/connection_handling.rb

@@ -45,7 +45,7 @@ module ConnectionHandling
     # The exceptions AdapterNotSpecified, AdapterNotFound and +ArgumentError+
     # may be returned on an error.
     def establish_connection(spec = nil)
-      raise RuntimeError, "Anonymous class is not allowed." unless name
+      raise "Anonymous class is not allowed." unless name
 
       spec     ||= DEFAULT_ENV.call.to_sym
       resolver =   ConnectionAdapters::ConnectionSpecification::Resolver.new configurations
@@ -93,8 +93,7 @@ def connection
 
     attr_writer :connection_specification_name
 
-    # Return the specification id from this class otherwise look it up
-    # in the parent.
+    # Return the specification name from the current class or its parent.
     def connection_specification_name
       unless defined?(@connection_specification_name)
         @connection_specification_name = self == Base ? "primary" : superclass.connection_specification_name