difference between executing curl_close() once or frequently?

Question

When is it necessary to close curl connection and release resources consumed by it?

Why do I ask this question, well quite simply because I was told, that PHP garbage collector does all of this and sometimes there is no need to close DB connection or call the __destruct method to release resources.

Since, that moment I actually started to think about where do I need to call it then? At the moment I'm interested with that question since I writing a small library for curl and I'd like to understand when do I need to user curl_close() function.

Thank you all for discussion and explanation of it.

Be carefull on using this for changing data by curl (post, put etc), for it can reuse old data in the background, see my answer: https://stackoverflow.com/a/67266458/4699609 — flexJoly, Apr 26 '21 at 12:26

score 12 · Answer 1 · edited Jun 20 '20 at 09:12

Results for 100 times curl_exec (fetching url with cache avoiding):

Executing in every loop:

for ($i = 0; $i < 100; ++$i) {
    $c = curl_init();
    curl_setopt($c, CURLOPT_URL, "http://www.google.com/?rand=" . rand());
    curl_exec($c);
    curl_close($c);
}

8.5 seconds

Executing only once :

$c = curl_init();
for ($i = 0; $i < 100; ++$i) {
    curl_setopt($c, CURLOPT_URL, "http://www.google.com/?rand=" . rand());
    curl_exec($c);
}
curl_close($c);

5.3 seconds

Decision: get used to always use optimal code in your tasks. (source)

score 5 · Accepted Answer · answered Oct 03 '10 at 14:11

5

as far as i understand it. The GC only cleans up resources that are no longer used/referenced. as whenever the curl variable fall out of scope, it'll be cleaned up. But that might only happen after the script has finished, or whenever the session is destroyed (depending on scope).

But to be on the safe side, just follow common sense.. close it when its no longer needed.

answered Oct 03 '10 at 14:11

Oliver O'Neill

1,229
6
11

7

@Eugene - Don't you close your front door after going out? ;) – Christian Feb 04 '11 at 16:15
4

@Christian Sciberras Depends. – Eugene Feb 07 '11 at 14:01
2

@Christian Sciberras - Great comparison. – Karthik Malla Aug 06 '11 at 19:04
24

If I had a door that closes automatically when I leave, then no - I would not close them manually. – Robo Robok Mar 15 '15 at 10:22
@RoboRobok That's one hell of a door if it self-destructs your house; or should we say - 'a little housekeeping'. – Leo Nov 03 '16 at 21:30

score 1 · Answer 3 · edited Nov 24 '17 at 11:04

1

Depends. In my case since I was initializing curl instance in my custom CurlClient constructor

$this->ch = curl_init();

And then using same $curlClient object for multiple api calls, closing the instance

curl_close($this->ch);

would affect other API calls. Methods using the same object will not work, so I'm not closing it.

edited Nov 24 '17 at 11:04

RediOne1

10,389
6
25
46

answered Nov 24 '17 at 10:28

R Sun

1,353
14
17

difference between executing curl_close() once or frequently?

3 Answers3

Executing in every loop:

Executing only once :

Linked