No http response for some get request occasionally

I’m going to deploy the current slim api to a new web server(centos6.5 apache 2.2.15, php5.3.3). I can not get http response occasionally while I access the same url more times, such as However, it work well on old web server.
Finally, I compare the php.ini and turn off xCache. The problem can not happen any more.
I wonder the reason, Thank a lot!

While I don’t know the underlying reason for your issue, I would suggest you upgrade to a more recent (5.6.x, or at least the most recent 5.3.x version) of PHP … version 5.3 is quite old and since you say that it works well on an older web server, it might just be an issue with your 5.3.3 version.

the version of centos, apache, php is the same on the old environment and the new one. Thanks