Sorry, I got it incorrectly since it was obvious to me that curl_exec
works fine in parallel in separate requests.
It seems that the testing method you use got the problem. If you start a
session (or auto starts) all the requests are in the same session.
Session data is locked to prevent concurrent writes only one script may
operate on a session at any time
So until the session_write_close is called , no output will be given.
check the script without starting the session or call
session_write_close() before the curl_exec call .

Waruna

On 3/16/2011 1:28 PM, Kuberan Marimuthu wrote:
> Hi Waruna,
>
> His scenario is different. When more than one request is made to a PHP
> script that makes a curl_exec, will the HTTP request happen concurrently ?
>
> regards,
> Kuberan Marimuthu
> On 16-Mar-2011, at 1:20 PM, Waruna Geekiyanage wrote:
>
>> 1. Initialize curl. (|curl_init|
>> <http://us3.php.net/manual/en/function.curl-init.php>, or
>> |curl_multi_init|
>> <http://www.php.net/manual/en/function.curl-multi-init.php>)
>> 2. Do thing(s). (in multiple |curl_exec|
>> <http://us2.php.net/manual/en/function.curl-exec.php> calls if
>> needed, or |curl_multi_exec|
>> <http://www.php.net/manual/en/function.curl-multi-exec.php>)
>> 3. Close curl. (|curl_close|
>> <http://www.php.net/manual/en/function.curl-close.php> or
>> |curl_multi_close|
>> <http://www.php.net/manual/en/function.curl-multi-close.php>)
>>
>> http://www.php.net/manual/en/function.curl-multi-init.php
>>
>>
>> On 3/16/2011 1:05 PM, Kuberan Marimuthu wrote:
>>> Can somebody throw some light on this. Is it true that php-curl binding does not scale for more than one request at a time ?? I am really curious
>>>
>>> On 16-Mar-2011, at 6:12 AM, John Lange wrote:
>>>
>>>> I have some code (written in PHP) that checks on the status of a
>>>> "server" but I need this code to scale up to hundreds of parallel
>>>> checks.
>>>>
>>>> For example, you call the script like this:
>>>>
>>>> http://mytest.com/checkserver.php?ip=10.11.12.13
>>>>
>>>> where the ip=X.X.X.X is different every time depending on which server
>>>> you are checking.
>>>>
>>>> And the PHP for checkserver.php looks something like this:
>>>>
>>>> <?php
>>>>
>>>> $ch = curl_init();
>>>> curl_setopt($ch, CURLOPT_URL,"http://".$ip."/status.html");
>>>> curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
>>>> $output = curl_exec($ch);
>>>> curl_close($ch);
>>>>
>>>> ?>
>>>>
>>>> To my way of thinking, this should scale easily. Lets say 200 people
>>>> hit the page at the same time all passing different "ip=" values, this
>>>> should check all 200 different IPs in parallel and return results.
>>>>
>>>> It doesn't. I wrote this little bash script to test it (yes I'm using
>>>> command line curl to test php-curl, please don't be confused by that):
>>>>
>>>> ---
>>>> #!/bin/bash
>>>>
>>>> IPS="10.18.136.20
>>>> 10.18.136.21
>>>> 10.18.136.22
>>>> ... ( a hundred more IPs)"
>>>>
>>>> for IP in $IPS ; do
>>>> curl -shttp://mytest.com/checkserver.php?ip=$IP &
>>>> done
>>>> ---
>>>>
>>>> All the curl commands launch into the background as you expect and I
>>>> see all the apache child threads startup, but the results return only
>>>> one by one. It's like each php-curl somehow blocks all the others.
>>>>
>>>> I can't for the life of me figure out how this can be possible. Each
>>>> apache thread should run it's PHP in a separate thread and return in
>>>> parallel.
>>>>
>>>> The only thing I can think of is that php is tracking all the requests
>>>> as being part of the same session and imposing some limit on the
>>>> outbound curl requests? But there is no global configuration for
>>>> php-curl so how would you overcome this?
>>>>
>>>> Just thought someone might have had to do something similar in the
>>>> past and run into this.
>>>>
>>>> By the way, it's not an OS limit or anything like that because if I
>>>> bypass php if I go direct with command line curl like this:
>>>>
>>>> for IP in $IPS ; do
>>>> curl -shttp://".$IP"/status.html&
>>>> done
>>>>
>>>> It works just exactly as you'd expect, all results return in parallel
>>>> so it's got to be a problem with either PHP or apache.
>>>>
>>>> --
>>>> John Lange
>>>> www.johnlange.ca
>>>> _______________________________________________
>>>> http://cool.haxx.se/cgi-bin/mailman/listinfo/curl-and-php
>>> _______________________________________________
>>> http://cool.haxx.se/cgi-bin/mailman/listinfo/curl-and-php
>>
>>
>> --
>>
>> Thank You,
>> Waruna Geekiyanage
>>
>> M: +94 71 4168164
>> E: waruna.ns_at_gmail.com <mailto:warunans_at_gmail.com>
>> MSN: warunans_at_hotmail.com
>> GTalk: waruna.ns
>> ICQ: 225184383
>> Yahoo: warunans
>> Skype: warunans
>>
>> _______________________________________________
>> http://cool.haxx.se/cgi-bin/mailman/listinfo/curl-and-php
>

-- 
Thank You,
Waruna Geekiyanage
M: +94 71 4168164
E: waruna.ns_at_gmail.com <mailto:warunans_at_gmail.com>
MSN: warunans_at_hotmail.com
GTalk: waruna.ns
ICQ: 225184383
Yahoo: warunans
Skype: warunans

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Received on 2011-03-16