Should I close cURL or not?

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.