How resource intensive is PHP's cURL? - php

Question

I am collecting market prices from different exchanges, the exchanges are set up for 1000's of requests a second however I am concerned that when my website is under heavy use this cURL function will be too resource intensive on my server.
Here is the cURL function, which gets results from between 2 and 4 exchanges (depending if an exchange timeouts):
function curl($exchange,$timeout) {
$a = curl_init();
curl_setopt($a, CURLOPT_TIMEOUT, $timeout);
curl_setopt($a, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($a,CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($a, CURLOPT_HTTPHEADER, array('Accept: application/json', 'Content-Type: application/json'));
curl_setopt($a, CURLOPT_URL, $exchange);
$result = curl_exec($a);
$httpCode = curl_getinfo($a, CURLINFO_HTTP_CODE);
if($httpCode == 200) {
return json_decode($result);
}
else {
return false;
}
curl_close($a);
}
I am using AJAX to load the script asynchronously since it takes a few seconds to complete. It is loaded on the homepage and I am anticipating ~15,000 unique hits a day.
Will I run into issues if cURL is called upon many times a second and if so is there a better alternative?

Answer 1

One option would be to implement a caching mechanism , this certainly will reduce the server's overhead . Frameworks like ZF , Symfony and Laravel have this mechanism build-in . For instance , in Laravel the implementation is simple as :
Cache::put('key', 'value', $minutes); .
// Retrieving the data
if (Cache::has('key'))
{
// ......
$value = Cache::get('key');
// .......
}
On what persisted layer the data will be cached (file , Memcached or Redis) is up to us . In Laravel its just a single configuration option (provided that our server has the aforementioned services installed) . We should also implement a "Queue" service to run the "time consuming" tasks in the background (Beanstalkd , Ironio , Amazon's SQS) . Combined with a cron-job , our Queue service could update / refresh the cached data .On a shared hosted environment the most obvious choice is to use "file" for caching and a cloud based Queue (Ironio has also a free tier) . Hope my comment gave you a starting point .

Answer 2

Instead of doing a cURL request for every visitor, set up a scheduled task with Cron (et al) to update a local cache in, say, a MySQL table every few minutes. Then you just have the overhead of reading your cache instead of having to make multiple cURL requests for every page load.
To answer the question in the title: not hugely intensive. You'll have to wait for the network of course, but I don't think cURL will be your bottleneck, especially if you're only requesting data to update a local cache.