Squash memory leak when calling flush with an empty buffer

[#1552 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

activesupport/lib/active_support/buffered_logger.rb

@@ -96,9 +96,12 @@ def flush
       @guard.synchronize do
         unless buffer.empty?
           old_buffer = buffer
-          clear_buffer
           @log.write(old_buffer.join)
         end
+
+        # Important to do this even if buffer was empty or else @buffer will
+        # accumulate empty arrays for each request where nothing was logged.
+        clear_buffer
       end
     end
 

activesupport/test/buffered_logger_test.rb

@@ -137,4 +137,10 @@ def test_logger_should_maintain_separate_buffers_for_each_thread
     assert @output.string.include?("a\nb\nc\n")
     assert @output.string.include?("x\ny\nz\n")
   end
+
+  def test_flush_should_remove_empty_buffers
+    @logger.send :buffer
+    @logger.expects :clear_buffer
+    @logger.flush
+  end
 end