1 files changed, 5 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 0d850c7625..ccd2899489 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -1,5 +1,5 @@
 require 'thread'
-require 'concurrent'
+require 'concurrent/map'
 require 'monitor'
 
 module ActiveRecord
@@ -197,7 +197,7 @@ module ActiveRecord
 
             elapsed = Time.now - t0
             if elapsed >= timeout
-              msg = 'could not obtain a database connection within %0.3f seconds (waited %0.3f seconds)' %
+              msg = 'could not obtain a connection from the pool within %0.3f seconds (waited %0.3f seconds); all pooled connections were in use' %
                 [timeout, elapsed]
               raise ConnectionTimeoutError, msg
             end
@@ -960,12 +960,11 @@ module ActiveRecord
       def call(env)
         testing = env['rack.test']
 
-        response = @app.call(env)
-        response[2] = ::Rack::BodyProxy.new(response[2]) do
+        status, headers, body = @app.call(env)
+        proxy = ::Rack::BodyProxy.new(body) do
           ActiveRecord::Base.clear_active_connections! unless testing
         end
-
-        response
+        [status, headers, proxy]
       rescue Exception
         ActiveRecord::Base.clear_active_connections! unless testing
         raise