In our recent project we were concerned
about performance of our web services. We were rebuilding the system and old
system was really good in performance which was a challenge for us.
Initially when we started building system
and selected Drupal as CMS + Framework for our system we considered performance
issue as well. Our main concern was that Drupal’s bootstrap takes too much time
and it calls many irrelevant functions. After deployment of Alpha release we
load tested system using JMeter and monitored system performance using several
server monitoring tools (Monit, Munin, Apache Logs, and New Relic). We found
that our system was taking up to 10 sec for simple web service functions.
After first cycle of optimization we
found issues in Ultimate Cron related community module. It was calling Drupal’s
cron every minute and was taking too many resources. We simply uninstalled
Ultimate Cron and decided to use crontab. We optimized our custom code as
well.
Performance improved but was still not
satisfactory. New Relic reports showed that issue was in how Drupal handles a
request. It was calling many extra functions for web services and was
generating useless http requests. We observed that these extra requests and
function calls are taking up to 90 % of time.
At this point we were very disappointed
by Drupal however our research revealed that web services are not implemented
properly.
We used the delivery callback property of
menu entry to specify the function to be used to render the results of
our page callback. The default delivery callback is drupal_deliver_html_page. The page handler for the AJAX callback page
at system/ajax uses ajax_deliver
to return a JSON data.
This allows to properly separate the page
logic (i.e. getting to data to output) from the rendering (i.e. formatting the
data).
This improved our performance and now our
system servers a web/ajax service/request in 200 - 300 milliseconds. Following
is code example of proper implementation of web services...
/**
/**
* Web/Ajax service/request menu
*/
$menu_items['menu-URL'] = array(
'title' => 'Service Title',
'type' => MENU_CALLBACK,
'delivery callback' => 'ajax_deliver',
'page callback' => 'test_function',
'access callback' => true,
);
/**
* test function
*/function test_function() {
//function logic and code
echo json_encode(array('response' => $response)); //JSON result
drupal_exit(); //This is required to avoid junk data in response
}
*/
$menu_items['menu-URL'] = array(
'title' => 'Service Title',
'type' => MENU_CALLBACK,
'delivery callback' => 'ajax_deliver',
'page callback' => 'test_function',
'access callback' => true,
);
/**
* test function
*/function test_function() {
//function logic and code
echo json_encode(array('response' => $response)); //JSON result
drupal_exit(); //This is required to avoid junk data in response
}
