Should I close cURL or not? - php

Question

I have a function that calls 3 different APIs using cURL multiple times. Each API's result is passed to the next API called in nested loops, so cURL is currently opened and closed over 500 times.
Should I leave cURL open for the entire function or is it OK to open and close it so many times in one function?

Answer 1

There's a performance increase to reusing the same handle. See: Reusing the same curl handle. Big performance increase?
If you don't need the requests to be synchronous, consider using the curl_multi_* functions (e.g. curl_multi_init, curl_multi_exec, etc.) which also provide a big performance boost.
UPDATE:
I tried benching curl with using a new handle for each request and using the same handle with the following code:
ob_start(); //Trying to avoid setting as many curl options as possible
$start_time = microtime(true);
for ($i = 0; $i < 100; ++$i) {
$rand = rand();
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.google.com/?rand=" . $rand);
curl_exec($ch);
curl_close($ch);
}
$end_time = microtime(true);
ob_end_clean();
echo 'Curl without handle reuse: ' . ($end_time - $start_time) . '<br>';
ob_start(); //Trying to avoid setting as many curl options as possible
$start_time = microtime(true);
$ch = curl_init();
for ($i = 0; $i < 100; ++$i) {
$rand = rand();
curl_setopt($ch, CURLOPT_URL, "http://www.google.com/?rand=" . $rand);
curl_exec($ch);
}
curl_close($ch);
$end_time = microtime(true);
ob_end_clean();
echo 'Curl with handle reuse: ' . ($end_time - $start_time) . '<br>';
and got the following results:
Curl without handle reuse: 8.5690529346466
Curl with handle reuse: 5.3703031539917
So reusing the same handle actually provides a substantial performance increase when connecting to the same server multiple times. I tried connecting to different servers:
$url_arr = array(
'http://www.google.com/',
'http://www.bing.com/',
'http://www.yahoo.com/',
'http://www.slashdot.org/',
'http://www.stackoverflow.com/',
'http://github.com/',
'http://www.harvard.edu/',
'http://www.gamefaqs.com/',
'http://www.mangaupdates.com/',
'http://www.cnn.com/'
);
ob_start(); //Trying to avoid setting as many curl options as possible
$start_time = microtime(true);
foreach ($url_arr as $url) {
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_exec($ch);
curl_close($ch);
}
$end_time = microtime(true);
ob_end_clean();
echo 'Curl without handle reuse: ' . ($end_time - $start_time) . '<br>';
ob_start(); //Trying to avoid setting as many curl options as possible
$start_time = microtime(true);
$ch = curl_init();
foreach ($url_arr as $url) {
curl_setopt($ch, CURLOPT_URL, $url);
curl_exec($ch);
}
curl_close($ch);
$end_time = microtime(true);
ob_end_clean();
echo 'Curl with handle reuse: ' . ($end_time - $start_time) . '<br>';
And got the following result:
Curl without handle reuse: 3.7672290802002
Curl with handle reuse: 3.0146431922913
Still quite a substantial performance increase.