Rails 2.2+ has this problem (testing on Rails HEAD)

So, in Rails 2.2+, there seems to be some memory problems with using config.log_level = :warn. Below I show the steps to reproduce this.

Creating project

compy:Rails Eddie$ rails logger_problem
      create  
      create  app/controllers
      create  app/helpers
      create  app/models
      create  app/views/layouts
      create  config/environments
      create  config/initializers
      create  config/locales
      create  db
      create  doc
      create  lib
      create  lib/tasks
      create  log
      create  public/images
      create  public/javascripts
      create  public/stylesheets
      create  script/performance
      create  script/process
      create  test/fixtures
      create  test/functional
      create  test/integration
      create  test/performance
      create  test/unit
      create  vendor
      create  vendor/plugins
      create  tmp/sessions
      create  tmp/sockets
      create  tmp/cache
      create  tmp/pids
      create  Rakefile
      create  README
      create  app/controllers/application.rb
      create  app/helpers/application_helper.rb
      create  test/test_helper.rb
      create  test/performance/browsing_test.rb
      create  config/database.yml
      create  config/routes.rb
      create  config/initializers/inflections.rb
      create  config/initializers/mime_types.rb
      create  config/initializers/new_rails_defaults.rb
      create  config/locales/en.yml
      create  config/boot.rb
      create  config/environment.rb
      create  config/environments/production.rb
      create  config/environments/development.rb
      create  config/environments/test.rb
      create  script/about
      create  script/console
      create  script/dbconsole
      create  script/destroy
      create  script/generate
      create  script/performance/benchmarker
      create  script/performance/profiler
      create  script/performance/request
      create  script/process/reaper
      create  script/process/spawner
      create  script/process/inspector
      create  script/runner
      create  script/server
      create  script/plugin
      create  public/dispatch.rb
      create  public/dispatch.cgi
      create  public/dispatch.fcgi
      create  public/404.html
      create  public/422.html
      create  public/500.html
      create  public/index.html
      create  public/favicon.ico
      create  public/robots.txt
      create  public/images/rails.png
      create  public/javascripts/prototype.js
      create  public/javascripts/effects.js
      create  public/javascripts/dragdrop.js
      create  public/javascripts/controls.js
      create  public/javascripts/application.js
      create  doc/README_FOR_APP
      create  log/server.log
      create  log/production.log
      create  log/development.log
      create  log/test.log
compy:Rails Eddie$ cd logger_problem/
compy:logger_problem Eddie$ cp -R ../test_project/vendor/rails vendor/
compy:logger_problem Eddie$ script/generate resource tasks
      exists  app/models/
      exists  app/controllers/
      exists  app/helpers/
      create  app/views/tasks
      exists  test/functional/
      exists  test/unit/
      create  test/unit/helpers/
  dependency  model
      exists    app/models/
      exists    test/unit/
      exists    test/fixtures/
      create    app/models/tasks.rb
      create    test/unit/tasks_test.rb
      create    test/fixtures/tasks.yml
      create    db/migrate
      create    db/migrate/20081210205128_create_tasks.rb
      create  app/controllers/tasks_controller.rb
      create  test/functional/tasks_controller_test.rb
      create  app/helpers/tasks_helper.rb
      create  test/unit/helpers/tasks_helper_test.rb
       route  map.resources :tasks
compy:logger_problem Eddie$ rake db:migrate
(in /Users/Eddie/Projects/Rails/logger_problem)
==  CreateTasks: migrating ====================================================
-- create_table(:tasks)
   -> 0.0041s
==  CreateTasks: migrated (0.0044s) ===========================================

Editing files

I added an index action, created index.html.erb, and set config.log_level = :warn

diff --git a/app/controllers/tasks_controller.rb b/app/controllers/tasks_controller.rb
index 1ad33d0..22407f0 100644
--- a/app/controllers/tasks_controller.rb
+++ b/app/controllers/tasks_controller.rb
@@ -1,2 +1,5 @@
 class TasksController < ApplicationController
+  def index
+    
+  end
 end
diff --git a/config/environments/production.rb b/config/environments/production.rb
index ec5b7bc..996f8eb 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -22,3 +22,5 @@ config.action_controller.perform_caching             = true

 # Disable delivery errors, bad email addresses will be ignored
 # config.action_mailer.raise_delivery_errors = false
+
+config.log_level = :warn

Starting Server

compy:logger_problem Eddie$ script/server -e production
=> Booting Mongrel
=> Rails 2.3.0 application starting on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server

Hitting it with httperf to simulate requests

compy:vendor Eddie$  ps -e -o vsz,pid,ppid,args | grep server
  104660 21431 21366 script/server -e production
compy:vendor Eddie$ httperf --server localhost --port 3000 --uri /tasks --num-conns 1000 > /dev/null 
compy:vendor Eddie$  ps -e -o vsz,pid,ppid,args | grep server
  126672 21431 21366 script/server -e production
compy:vendor Eddie$ httperf --server localhost --port 3000 --uri /tasks --num-conns 1000 > /dev/null 
compy:vendor Eddie$  ps -e -o vsz,pid,ppid,args | grep server
  147612 21431 21366 script/server -e production

As you should be able to see above, the memory usage (first column) grows quite a bit with each 1000 requests. Commenting out the config.log_level = :warn line stops this behavior.

If you need any more info I'd be happy to help.