Php sdk 2.0 err_empty_response


I did a simple php script to get a document by key from the couchbase cluster.
When I simulate some concurrent connections (less 10 concurrent connections) on the php server I get a blank page with the following error from the web navigator :


We get the same issue when we do quickly some page refresh with the F5 key.

Is that a bug on PHP SDK 2.0 ?

CentOS 7 64bit
apache 2.4.6
PHP Version 5.4.16

Couchbase 3 beta2 on CentOS 6.5 (same issue with Couchbase 2.5.1)

the Script :

$myCluster = new CouchbaseCluster(‘’);
$myBucket = $myCluster->openBucket(‘mybucket’, ‘mypassword’);
$res = $myBucket->get(‘k1X78RU’);

Apache error :
oct. 02, 2014 4:11:17 PM org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFOS: I/O exception (org.apache.commons.httpclient.NoHttpResponseException) caught when processing request: The server x.x.x.x failed to respond

I do not believe that this is an issue with the SDK, however I will investigate and see if I can reproduce the problem, please feel free to open an issue on our issue tracker:
Cheers, Brett