It seems randomly every 10 minutes or more the cache seems to reset. I think I am using it wrong. I am using APC to cache a 3 MegaByte HTML response. About 50 of them at any given time. As far as I understand using mmap_file_mask will use files instead of memory, so it won't hog up my memory but I still think it runs out of memory and resets itself.
It is a VPS with 1 GB of memory, normally when running free it shows between 512MB and 750 MB used (this is with my current 256 MB SHM size). Should I increase my SHM size from 256 to something higher?
Should I use APC for doing this or is it better to store the responses in files and just use that instead?
My APC INI is as follows:
extension = apc.so
apc.enabled = 1
apc.shm_segments = 1
apc.shm_size = 256
apc.optimization = 0
apc.num_files_hint = 10000
apc.ttl = 0
apc.user_ttl = 0
apc.gc_ttl = 0
apc.cache_by_default = 1
apc.filters = ""
apc.mmap_file_mask = "/tmp/apc.XXXXXX"
apc.slam_defense = 0
apc.file_update_protection = 2
apc.enable_cli = 0
apc.max_file_size = 10M
apc.stat = 1
apc.write_lock = 1
apc.report_autofilter = 0
apc.include_once_override = 0
apc.localcache = 0
apc.localcache.size = 512
apc.coredump_unmap = 0
apc.stat_ctime = 0
Edit: I updated the memory to 512 MB and it lasted for a few hours, and then I went to bed. When I woke up all the cache's were gone. Seems it could be a memory issue? I might just rely on files or MySQL, debugging APC isn't worth the milliseconds of time saved on page load.
Here is the info as asked:
[num_slots] => 8192
[ttl] => 0
[num_hits] => 490
[num_misses] => 390
[num_inserts] => 13663
[expunges] => 0
[start_time] => 1355644615
[mem_size] => 5271328
[num_entries] => 204
[file_upload_progress] => 1
[memory_type] => mmap
[locking_type] => pthread mutex
[cache_list] => Array
And then it just displays the array of the caches, nothing really useful for debugging any issues I think. Nothing stands out pre-cache clearing. Not much changes from pre and post random cache clearer. No idea of the issue, 512 MB of memory should be enough for 3 MB x 50 entries. Even then, I don't even want it to use memory. I want it to use files.
Edit 2:
As requested, here is the APC code I use:
<?php
$unique_options = "query_options_that_are_unique_to_1_of_the_50_caches";
$refresh_interval = 60*15;
$refresh_triggered = (isset($_REQUEST['refresh']));
// Try to get the APC Cache, if fails, then it was never created
if ($cache_array = apc_fetch(md5($unique_options))) {
// I got the cache, using its creation_time, see if its refreshable
$seconds_since_last_refresh = (time() - $cache_array['creation_time']);
$can_refresh = ($seconds_since_last_refresh >= $refresh_interval);
} else {
// Apparently this has never had a cache created, so create it
apc_store(md5($unique_options), array('data'=> get_json($unique_options), 'creation_time'=>time()), 0);
$cache_array = apc_fetch(md5($unique_options));
$refresh_triggered = false;
}
// If the cache already existed, and the user is attempting to refresh the cache, and they are allowed to refresh it, then refresh it.
if($refresh_triggered) {
if($can_refresh) {
apc_store(md5($unique_options), array('data'=> get_json($unique_options), 'creation_time'=>time()), 0);
$cache_array = apc_fetch(md5($unique_options));
} else {
echo "You can only refresh every 15 minutes<br><br>";
}
}
$current_url = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] && !in_array(strtolower($_SERVER['HTTPS']),array('off','no'))) ? 'https' : 'http' . '://'.$_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$url_parts = parse_url($current_url);
$url_without_query = $url_parts['scheme'] . '://' . $url_parts['host'] . $url_parts['path'];
foreach($_GET as $key => $value) {
if($key != "refresh")
$query .= "$key=$value&";
}
echo "Data was last refreshed " . ($seconds_since_last_refresh) . "seconds ago (<a href='$url_without_query?{$query}refresh'>Refresh Now</a>)<br><br>";
$data = $cache_array['data'];
// Now process the the information that was cached
// ...
?>
