Randomly, a Phalcon 2.0 application returns empty response. After retrying, without changing any code or input, I get a response.
I have two subdomains on the same physical machine. The first subdomain is a frontend API, and the second is a backend API. The frontend calls the backend over HTTP (not HTTPS) using CURL. Approximately 2/3 of the calls come back empty. When I retry 2 or 3 times, I get a response. The problem is less pronounced when I access the backend directly, and more pronounced when I access the frontend and it in turn calls the backend before responding. Depending on which of the two subdomans failed, I get either an empty response from the frontend, or an error "Empty reply from server" when the internal call to the backend service comes back empty.
Cache-Control header set to no-cache, and curl option CURLOPTFRESHCONNECT set to true don't have any effect.
Apache error log shows the following when the error occurs:
[core:notice] [pid 7062] AH00052: child pid 7070 exit signal Segmentation fault (11)
7070 is the process of the currently executing request.
On several occasions, I also noticed the index.php being executed twice back-to-back.
My application works fine with Phalcon 1.3.4.
My configuration: Apache 2.4 and PHP 5.5.9 on Linux Mint 64-bit running in a VMWare virtual machine with 4 GB of memory and 4 CPU cores.
Thank you for your help.
UPDATE: I don't believe it is any of these already reported issues:
If I retry, it would eventually work without me changing any code, settings, or input.