The short answer.
The plugin is using internal wordpress functions which rely on curl.
Have a look at the wp-includes/class-http.php file. The request function line 1043 and the underlying code the timeout is set to 5 seconds. Therefore when curl does a request and it takes longer than 5 seconds you will get this issue.
A possible solution would be to override the wordpress defaults but Im not sure how to do that.
The long answer.
I did some debugging and was able to work out the following.
The problem on my development machine locally was that name-server lookups were taking forever. Im using centos 6.3 but generally Linux uses /etc/resolv.conf where nameservers can be specified. That was set to a nameserver that was slow in responding. The underlying bits of Curl use this name server lookup configuration.
I changed it to 8.8.8.8 which is googles dns servers and that solved the problem.
What you can do to debug curl locally is the following.
// create curl resource
$ch = curl_init();
// set url
curl_setopt($ch, CURLOPT_URL, "google.com");
//return the transfer as a string
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
// $output contains the output string
$output = curl_exec($ch);
//get the info of the last request
$info = curl_getinfo($ch);
print_r($info);
// close curl resource to free up system resources
curl_close($ch);
For me the output looked like this before I changed the nameserver. namelookup_time is the culprit.
[url] => https://google.com
[content_type] => text/html; charset=UTF-8
[http_code] => 301
[header_size] => 321
[request_size] => 49
[filetime] => -1
[ssl_verify_result] => 0
[redirect_count] => 0
[total_time] => 5.102859
[namelookup_time] => 5.0526
[connect_time] => 5.071828
[pretransfer_time] => 5.071922
[size_upload] => 0
[size_download] => 219
[speed_download] => 42
[speed_upload] => 0
[download_content_length] => 219
[upload_content_length] => 0
[starttransfer_time] => 5.102791
[redirect_time] => 0
[certinfo] => Array
(
)
[primary_ip] => 173.194.34.66
[redirect_url] => https://www.google.com/
after changing the nameserver the debugging info looked as follows
Array
(
[url] => https://google.com
[content_type] => text/html; charset=UTF-8
[http_code] => 301
[header_size] => 321
[request_size] => 49
[filetime] => -1
[ssl_verify_result] => 0
[redirect_count] => 0
[total_time] => 0.079125
[namelookup_time] => 0.02969
[connect_time] => 0.049101
[pretransfer_time] => 0.049123
[size_upload] => 0
[size_download] => 219
[speed_download] => 2767
[speed_upload] => 0
[download_content_length] => 219
[upload_content_length] => 0
[starttransfer_time] => 0.079049
[redirect_time] => 0
[certinfo] => Array
(
)
[primary_ip] => 173.194.34.128
[redirect_url] => https://www.google.com/
)
Have a look at the difference in the two outputs between namelookup_time it is significantly reduced in the second output.
Hope this helps someone.
