Incorrectly set up APC for PHP?

Question

I decided to install APC to speed up the site that I work for. Sadly, I found out that it was already installed and enabled(The developer who first worked on the servers has moved on).

Then I decided to check the usage of it to see if it needs more memory allocated to it or not. This is when I discovered something weird. A simple file with this code:

<?php
    print_r(apc_cache_info());
?>

It would not work when served from apache. I get Error 320 (net::ERR_INVALID_RESPONSE): Unknown error. And there is nothing in the error log. From the cli on the server, it works fine. But it only says that my check_apc.php file is cached(name of the script that I was running).

So it looks like APC has not fully/correctly been set up. Any one know what the problem could be?

Contents of /etc/php.d/apc.ini:

; Enable apc extension module
extension = apc.so
; Options for the apc module
apc.enabled=1
apc.shm_segments=1
apc.optimization=0
apc.shm_size=32
apc.ttl=7200
apc.user_ttl=7200
apc.num_files_hint=1024
apc.mmap_file_mask=/tmp/apc.XXXXXX
apc.enable_cli=1
apc.cache_by_default=1

The server is running CentOS

Answer 1

Has anyone upgraded the version of php on the server since apc.so was created? It may be that apc.so was compiled against a different version of php.

If possible, try re-compiling apc.so against the current version of php. Or if you are using a package manager, try removing the apc package entirely and reinstall it.