From 396d599e24cbfa15c62b20fab8cc02cdba046ce3 Mon Sep 17 00:00:00 2001 From: Pratik Naik Date: Thu, 6 Nov 2008 01:10:30 +0530 Subject: Update guides from docrails --- .../guides/html/debugging_rails_applications.html | 192 +++++++++++++++++---- 1 file changed, 158 insertions(+), 34 deletions(-) (limited to 'railties/doc/guides/html/debugging_rails_applications.html') diff --git a/railties/doc/guides/html/debugging_rails_applications.html b/railties/doc/guides/html/debugging_rails_applications.html index bf1e442d59..95f5b39e4c 100644 --- a/railties/doc/guides/html/debugging_rails_applications.html +++ b/railties/doc/guides/html/debugging_rails_applications.html @@ -208,6 +208,8 @@ ul#navMain {
  • inspect
    • +
  • Debugging Javascript
    • +
  • @@ -253,6 +255,19 @@ ul#navMain {
  • + Debugging Memory Leaks + +
    • +
  • + Plugins for Debugging +
    • +
  • References
  • @@ -325,10 +340,7 @@ http://www.gnu.org/software/src-highlite -->

    You'll see something like this:

    -
    +
    --- !ruby/object:Post
 attributes:
   updated_at: 2008-09-05 22:55:47
@@ -340,8 +352,8 @@ attributes:
 attributes_cache: {}
 
 
-Title: Rails debugging guide
-
    +Title: Rails debugging guide +

    1.2. to_yaml

    Displaying an instance variable, or any other object or method, in yaml format can be achieved this way:

    @@ -358,10 +370,7 @@ http://www.gnu.org/software/src-highlite -->

    The to_yaml method converts the method to YAML format leaving it more readable, and then the simple_format helper is used to render each line as in the console. This is how debug method does its magic.

    As a result of this, you will have something like this in your view:

    -
    +
    --- !ruby/object:Post
 attributes:
 updated_at: 2008-09-05 22:55:47
@@ -372,8 +381,8 @@ id: "1"
 created_at: 2008-09-05 22:55:47
 attributes_cache: {}
 
-Title: Rails debugging guide
-
    +Title: Rails debugging guide +

    1.3. inspect

    Another useful method for displaying object values is inspect, especially when working with arrays or hashes. This will print the object value as a string. For example:

    @@ -389,14 +398,37 @@ http://www.gnu.org/software/src-highlite -->

    Will be rendered as follows:

    +
    +
    [1, 2, 3, 4, 5]
+
+Title: Rails debugging guide
    +
    +

    1.4. Debugging Javascript

    +

    Rails has built-in support to debug RJS, to active it, set ActionView::Base.debug_rjs to true, this will specify whether RJS responses should be wrapped in a try/catch block that alert()s the caught exception (and then re-raises it).

    +

    To enable it, add the following in the Rails::Initializer do |config| block inside environment.rb:

    +
    -
    [1, 2, 3, 4, 5]
-
-Title: Rails debugging guide
+
    config.action_view[:debug_rjs] = true
+
    +

    Or, at any time, setting ActionView::Base.debug_rjs to true:

    +
    +
    +
    ActionView::Base.debug_rjs = true
    +
    + + + +
    +Tip +For more information on debugging javascript refer to Firebug, the popular debugger for Firefox.
    +

    2. The Logger

    @@ -488,11 +520,8 @@ http://www.gnu.org/software/src-highlite -->

    Here's an example of the log generated by this method:

    -
    -
    Processing PostsController#create (for 127.0.0.1 at 2008-09-08 11:52:54) [POST]
+
    
+
    Processing PostsController#create (for 127.0.0.1 at 2008-09-08 11:52:54) [POST]
   Session ID: BAh7BzoMY3NyZl9pZCIlMDY5MWU1M2I1ZDRjODBlMzkyMWI1OTg2NWQyNzViZjYiCmZsYXNoSUM6J0FjdGl
 vbkNvbnRyb2xsZXI6OkZsYXNoOjpGbGFzaEhhc2h7AAY6CkB1c2VkewA=--b18cd92fba90eacf8137e5f6b3b06c4d724596a4
   Parameters: {"commit"=>"Create", "post"=>{"title"=>"Debugging Rails",
@@ -506,8 +535,8 @@ Post should be valid: true
  'I''m learning how to print in logs!!!', 'f', '2008-09-08 14:52:54')
 The post was saved and now is the user is going to be redirected...
 Redirected to #<Post:0x20af760>
-Completed in 0.01224 (81 reqs/sec) | DB: 0.00044 (3%) | 302 Found [http://localhost/posts]
-
    +Completed in 0.01224 (81 reqs/sec) | DB: 0.00044 (3%) | 302 Found [http://localhost/posts] +

    Adding extra logging like this makes it easy to search for unexpected or unusual behavior in your logs. If you add extra logging, be sure to make sensible use of log levels, to avoid filling your production logs with useless trivia.

    3. Debugging with ruby-debug

    @@ -540,12 +569,9 @@ http://www.gnu.org/software/src-highlite -->

    If you see the message in the console or logs:

    -
    -
    ***** Debugger requested, but was not available: Start server with --debugger to enable *****
-
    +
    +
    ***** Debugger requested, but was not available: Start server with --debugger to enable *****
    +

    Make sure you have started your web server with the option —debugger:

    @posts = Post.find(:all)
 (rdb:7)
    -

    Now it's time to play and dig into your application. A good place to start is by asking the debugger for help… so type: help (You didn't see that coming, right?)

    +

    Now it's time to explore and dig into your application. A good place to start is by asking the debugger for help… so type: help (You didn't see that coming, right?)

    (rdb:7) help
@@ -969,16 +995,104 @@ No breakpoints.

    Here's a good start for an .rdebugrc:

    +
    +
    set autolist
+set forcestep
+set listsize 25
    +
    +
    +

    4. Debugging Memory Leaks

    +
    +

    A Ruby application (on Rails or not), can leak memory - either in the Ruby code or at the C code level.

    +

    In this section, you will learn how to find and fix such leaks by using Bleak House and Valgrind debugging tools.

    +

    4.1. BleakHouse

    +

    BleakHouse is a library for finding memory leaks.

    +

    If a Ruby object does not go out of scope, the Ruby Garbage Collector won't sweep it since it is referenced somewhere. Leaks like this can grow slowly and your application will consume more and more memory, gradually affecting the overall system performance. This tool will help you find leaks on the Ruby heap.

    +

    To install it run:

    +
    +
    +
    sudo gem install bleak_house
    +
    +

    Then setup you application for profiling. Then add the following at the bottom of config/environment.rb:

    +
    -
    set autolist
-set forcestep
-set listsize 25
+
    require 'bleak_house' if ENV['BLEAK_HOUSE']
    +

    Start a server instance with BleakHouse integration:

    +
    +
    +
    RAILS_ENV=production BLEAK_HOUSE=1 ruby-bleak-house ./script/server
    +
    +

    Make sure to run a couple hundred requests to get better data samples, then press CTRL-C. The server will stop and Bleak House will produce a dumpfile in /tmp:

    +
    +
    +
    ** BleakHouse: working...
+** BleakHouse: complete
+** Bleakhouse: run 'bleak /tmp/bleak.5979.0.dump' to analyze.
    +
    +

    To analyze it, just run the listed command. The top 20 leakiest lines will be listed:

    +
    +
    +
      191691 total objects
+  Final heap size 191691 filled, 220961 free
+  Displaying top 20 most common line/class pairs
+  89513 __null__:__null__:__node__
+  41438 __null__:__null__:String
+  2348 /opt/local//lib/ruby/site_ruby/1.8/rubygems/specification.rb:557:Array
+  1508 /opt/local//lib/ruby/gems/1.8/specifications/gettext-1.90.0.gemspec:14:String
+  1021 /opt/local//lib/ruby/gems/1.8/specifications/heel-0.2.0.gemspec:14:String
+   951 /opt/local//lib/ruby/site_ruby/1.8/rubygems/version.rb:111:String
+   935 /opt/local//lib/ruby/site_ruby/1.8/rubygems/specification.rb:557:String
+   834 /opt/local//lib/ruby/site_ruby/1.8/rubygems/version.rb:146:Array
+  ...
    +
    +

    This way you can find where your application is leaking memory and fix it.

    +

    If BleakHouse doesn't report any heap growth but you still have memory growth, you might have a broken C extension, or real leak in the interpreter. In that case, try using Valgrind to investigate further.

    +

    4.2. Valgrind

    +

    Valgrind is a Linux-only application for detecting C-based memory leaks and race conditions.

    +

    There are Valgrind tools that can automatically detect many memory management and threading bugs, and profile your programs in detail. For example, a C extension in the interpreter calls malloc() but is doesn't properly call free(), this memory won't be available until the app terminates.

    +

    For further information on how to install Valgrind and use with Ruby, refer to Valgrind and Ruby by Evan Weaver.

    -

    4. References

    +

    5. Plugins for Debugging

    +
    +

    There are some Rails plugins to help you to find errors and debug your application. Here is a list of useful plugins for debugging:

    +
      +
    • +

      +Footnotes: Every Rails page has footnotes that link give request information and link back to your source via TextMate. +

      +
      • +
    • +

      +Query Trace: Adds query origin tracing to your logs. +

      +
      • +
    • +

      +Query Stats: A Rails plugin to track database queries. +

      +
      • +
    • +

      +Query Reviewer: This rails plugin not only runs "EXPLAIN" before each of your select queries in development, but provides a small DIV in the rendered output of each page with the summary of warnings for each query that it analyzed. +

      +
      • +
    • +

      +Exception Notifier: Provides a mailer object and a default set of templates for sending email notifications when errors occur in a Rails application. +

      +
      • +
    • +

      +Exception Logger: Logs your Rails exceptions in the database and provides a funky web interface to manage them. +

      +
      • +
    +
    +

    6. References

    -

    5. Changelog

    +

    7. Changelog

    Lighthouse ticket

    • +November 3, 2008: Accepted for publication. Added RJS, memory leaks and plugins chapters by Emilio Tagua +

      +
      • +
    • +

      October 19, 2008: Copy editing pass by Mike Gunderloy

      • -- cgit v1.2.3