利用Gearman实现并发查询（Multi-Query）

来源：互联网发布：oop面向对象编程编辑：程序博客网时间：2024/06/05 04:05

这个例子是想从数据库查询出几个结果集，一般的做法是，一个接一个的发送查询，然后汇总结果进行输出。

下面我们利用Gearman的gearman_client_run_tasks实现并发的查询，gearman_client_run_tasks接口可以一次性的提交多个任务，然后在callback函数中异步的处理结果。

PHP的示例如下：

The client:

<?php$client = new GearmanClient();$client->addServer();// initialize the results of our 3 "query results" here$userInfo = $friends = $posts = null;// This sets up what gearman will callback to as tasks are returned to us.// The $context helps us know which function is being returned so we can // handle it correctly.$client->setCompleteCallback(function(GearmanTask $task, $context) use (&$userInfo, &$friends, &$posts) {    switch($context) {        case 'lookup_user':            $userInfo = $task->data();            break;        case 'baconate':            $friends = $task->data();            break;        case 'get_latest_posts_by':            $posts = $task->data();            break;    }});// Here we queue up multiple tasks to be execute in *as much* parallelism as gearmand can give us$client->addTask('lookup_user', 'joe@joe.com', 'lookup_user');$client->addTask('baconate', 'joe@joe.com', 'baconate');$client->addTask('get_latest_posts_by', 'joe@joe.com', 'get_latest_posts_by');echo "Fetching...\n";$start = microtime(true);$client->runTasks();$totaltime = number_format(microtime(true) - $start, 2);echo "Got user info in: $totaltime seconds:\n";var_dump($userInfo, $friends, $posts);

The worker:

<?php$worker = new GearmanWorker();$worker->addServer();$worker->addFunction('lookup_user', function(GearmanJob $job){    // normally you'd so some very safe type checking and query binding to a database here.    // ...and we're gonna fake that.    sleep(3);    return 'The user requested ('. $job->workload() .') is 7 feet tall and awesome';});$worker->addFunction('baconate', function(GearmanJob $job){    sleep(3);    return 'The user ('. $job->workload() .') is 1 degree away from Kevin Bacon';});$worker->addFunction('get_latest_posts_by', function(GearmanJob $job){    sleep(3);    return 'The user ('. $job->workload() .') has no posts, sorry!';});while ($worker->work());

运行结果：

Fetching...Got user info in: 9.00 seconds:string(59) "The user requested (joe@joe.com) is 7 feet tall and awesome"string(56) "The user (joe@joe.com) is 1 degree away from Kevin Bacon"string(43) "The user (joe@joe.com) has no posts, sorry!"</span>

发现还是用了9S时间，那是因为只有一个worker，它只能是顺序执行。

一起运行三个worker或更多，再来试试：

Fetching...Got user info in: 3.00 seconds:string(59) "The user requested (joe@joe.com) is 7 feet tall and awesome"string(56) "The user (joe@joe.com) is 1 degree away from Kevin Bacon"string(43) "The user (joe@joe.com) has no posts, sorry!"</span>

这只是一个并行执行的例子，实际应用中可以有更好的并发性能。

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