Qiang Xue
12 years ago
29 changed files with 223 additions and 10 deletions
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Performance Tuning |
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================== |
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Application performance consists of two parts. First is the framework performance |
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and the second is the application itself. Yii has a pretty low performance impact |
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on your application out of the box and can be fine-tuned further for production |
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environment. As for the application, we'll provide some of the best practices |
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along with examples on how to apply them to Yii. |
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Preparing framework for production |
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---------------------------------- |
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### Disabling Debug Mode |
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First thing you should do before deploying your application to production environment |
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is to disable debug mode. A Yii application runs in debug mode if the constant |
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`YII_DEBUG` is defined as `true` in `index.php` so to disable debug the following |
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should be in your `index.php`: |
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```php |
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defined('YII_DEBUG') or define('YII_DEBUG', false); |
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``` |
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Debug mode is very useful during development stage, but it would impact performance |
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because some components cause extra burden in debug mode. For example, the message |
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logger may record additional debug information for every message being logged. |
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### Enabling PHP opcode cache |
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Enabling the PHP opcode cache improves any PHP application performance and lowers |
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memory usage significantly. Yii is no exception. It was tested with |
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[APC PHP extension](http://php.net/manual/en/book.apc.php) that caches |
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and optimizes PHP intermediate code and avoids the time spent in parsing PHP |
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scripts for every incoming request. |
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### Turning on ActiveRecord database schema caching |
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If the application is using Active Record, we should turn on the schema caching |
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to save the time of parsing database schema. This can be done by setting the |
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`Connection::enableSchemaCache` property to be `true` via application configuration |
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`protected/config/main.php`: |
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```php |
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return array( |
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// ... |
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'components' => array( |
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// ... |
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'db' => array( |
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'class' => 'yii\db\Connection', |
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'dsn' => 'mysql:host=localhost;dbname=mydatabase', |
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'username' => 'root', |
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'password' => '', |
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'enableSchemaCache' => true, |
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// Duration of schema cache. |
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// 'schemaCacheDuration' => 3600, |
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// Name of the cache component used. Default is 'cache'. |
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//'schemaCache' => 'cache', |
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), |
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'cache' => array( |
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'class' => 'yii\caching\FileCache', |
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), |
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), |
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); |
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``` |
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Note that `cache` application component should be configured. |
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### Combining and Minimizing Assets |
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TBD |
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### Using better storage for sessions |
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By default PHP uses files to handle sessions. It is OK for development and |
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small projects but when it comes to handling concurrent requests it's better to |
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switch to another storage such as database. You can do so by configuring your |
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application via `protected/config/main.php`: |
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```php |
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return array( |
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// ... |
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'components' => array( |
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'session' => array( |
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'class' => 'yii\web\DbSession', |
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// Set the following if want to use DB component other than |
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// default 'db'. |
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// 'db' => 'mydb', |
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// To override default session table set the following |
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// 'sessionTable' => 'my_session', |
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), |
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), |
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); |
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``` |
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You can use `CacheSession` to store sessions using cache. Note that some |
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cache storages such as memcached has no guaranteee that session data will not |
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be lost leading to unexpected logouts. |
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Improving application |
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--------------------- |
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### Using Serverside Caching Techniques |
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As described in the Caching section, Yii provides several caching solutions that |
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may improve the performance of a Web application significantly. If the generation |
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of some data takes long time, we can use the data caching approach to reduce the |
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data generation frequency; If a portion of page remains relatively static, we |
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can use the fragment caching approach to reduce its rendering frequency; |
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If a whole page remains relative static, we can use the page caching approach to |
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save the rendering cost for the whole page. |
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### Leveraging HTTP to save procesing time and bandwidth |
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TBD |
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### Database Optimization |
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Fetching data from database is often the main performance bottleneck in |
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a Web application. Although using caching may alleviate the performance hit, |
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it does not fully solve the problem. When the database contains enormous data |
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and the cached data is invalid, fetching the latest data could be prohibitively |
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expensive without proper database and query design. |
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Design index wisely in a database. Indexing can make SELECT queries much faster, |
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but it may slow down INSERT, UPDATE or DELETE queries. |
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For complex queries, it is recommended to create a database view for it instead |
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of issuing the queries inside the PHP code and asking DBMS to parse them repetitively. |
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Do not overuse Active Record. Although Active Record is good at modelling data |
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in an OOP fashion, it actually degrades performance due to the fact that it needs |
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to create one or several objects to represent each row of query result. For data |
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intensive applications, using DAO or database APIs at lower level could be |
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a better choice. |
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Last but not least, use LIMIT in your SELECT queries. This avoids fetching |
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overwhelming data from database and exhausting the memory allocated to PHP. |
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### Using asArray |
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A good way to save memory and processing time on read-only pages is to use |
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ActiveRecord's `asArray` method. |
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```php |
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class PostController extends Controller |
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{ |
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public function actionIndex() |
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{ |
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$posts = Post::find()->orderBy('id DESC')->limit(100)->asArray()->all(); |
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echo $this->render('index', array( |
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'posts' => $posts, |
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)); |
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} |
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} |
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``` |
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In the view you should access fields of each invidual record from `$posts` as array: |
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```php |
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foreach($posts as $post) { |
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echo $post['title']."<br>"; |
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} |
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``` |
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Note that you can use array notation even if `asArray` wasn't specified and you're |
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working with AR objects. |
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### Processing data in background |
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In order to respond to user requests faster you can process heavy parts of the |
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request later if there's no need for immediate response. |
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- Cron jobs + console. |
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- queues + handlers. |
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TBD |
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