How to flush the APC cache in Prestashop - caching

In the backoffice of Prestashop, there is no option to flush the cache (Advanced parameters - Performance), it is only possible to disable the cache.
Different types of cache and how to flush them
Smarty compile cache: Delete the subfolders under cache/smarty/compile
Smarty template cache: Delete the subfolders under cache/smarty/cache
Cache using Filesystem: Delete the subfolders under cache/cachefs
But how can I go about flushing the cache if I use APC Cache ?
A subsidiary question: Is it possible to set a global ttl ? By default, everything gets cached forever.

To flush the APC user cache, you have to install the administration interface for APC (apc.php). This file is bundled with the download for APC. Just copy it to a folder that is accessible from the web, the edit it to set a password.
After that, you can connect and flush the cache when needed. It is possible to flush the system cache and the user cache separately.

You could write a simple php function: add all cache dirs to array and check it:
foreach ($cacheDirs as $dir)
if (file_exists($dir))
$this->emptydir($dir);
Other way, use a free module to clean it: http://www.prestatoolbox.com/free-prestashop-modules/122-clear-the-cache-of-prestashop.html

Related

problem in clearing Laravel5.7 cache (memcached driver)

I have upgraded my application laravel version to 5.7 . cache driver is memcached. also i'm using docker compose with separate container for memcached, application, and webserver.
When I try cleaning cache it returns Failed to clear cache. Make sure you have the appropriate permissions.
when I change the cache driver to file it works well. Also, when I'm not running it in docker space it works well!
The problem is probably about flushing memcached. because when i try to clear it manually in my application it returns error 19 which stands for Memcached::RES_SOME_ERRORS! and I dont know what this means exactly!
p.s. and yes, I've created the data folder in storage/framework/cache directory with appropriate permissions.
Any suggestion?
I am assuming you are trying to set up a routine cronjob to clear the cache.
Try running the clear command while you're logged on in a wheel user account
sudo php artisan cache:clear
If it works, you may need to set up that cacheclear on an account with an appropriate access level for memory management tasks.
as I'm using docker i should define hosts as conatiner names.
so I defined MEMCACHED_HOST=memcached in .env file :-"
also i defined application dependency for memcached container.

How do I disable Symfony from writing _sess files to my /tmp directory

I am new to symfony and am responsible for a site that I didn't build. For some reason the site is on a live server but running in dev mode. - Im not sure why??
That aside - The website keeps writing _sess files to my /tmp directory. The contents of each _sess file is exactly the same. See below:
_symfony2|a:3:{s:10:"attributes";a:0:{}s:7:"flashes";a:0:{}s:6:"locale";s:2:"en";}
Do I really need all of these files? Can anyone suggest a way of disabling this feature?
Thanks in advance
The default session storage of Symfony2 writes the session information to file(s). The location these files are written to is determined by the config parameter framework.session.save_path. The default value for this is %kernel.cache.dir%/sessions. This means that in a default installation of symfony the session files would be written to the cache directory for the environment.
However, this can be a problem as the cache directory has to be cleared each time an app is deployed, thus logging all the users out. Therefore presumably your app has been configured (most likely in config.yml) to store the session files in /tmp.
As I understand it, sessions that have expired should be garbage-collected at some point. Symfony also has some config params that affect this - see the FrameworkBundle Configuration. I don't know how much traffic your website has but obviously you do need the session files for active sessions. If you think you have a lot of expired sessions you could try tweaking the gc config params.
Alternatively, if having the session files in /tmp is specifically the problem you could relocate them (by changing the value of the framework.session.save_path) or use PDOSessionHandler to store sessions in the database.
I have this problem with symfony 1.4.20 on a web site I inherited.
It is writing files to
/var/lib/php/sessions
every second, until the server runs out of iNodes.
I've tried changing settings in settings.yml. app.yml and PHP session variables.
Nothing sees to be working though, the only way I can stop it is to change the ownership of /var/lib/php/sessions to root and that prevents any session files being created.

How to clear OpenX-hosted cache?

well it is easy to set/clear OpenX cache by clearing openx/var/cache directory or by setting cache time by navigating to Configuration > Global Settings > Banner Delivery Settings and set cache time, BUT is it possible to clear cache for the openx-hosted version ??
you can't. You need to be admin... Wait 20 min or install openx on your server.

Magento - Magento Cache

I am using memcache.
I want to understand what is stored in Magento cache and how?
Do magento stores cache variable with website scope or store scope?
I have googled and greped the code but couldnt conclude anything,
Please if someone can direct me to correct links and path
Thanks & Regards,
Saurabh
If you go to the Cache Management section of the admin area you can see what it caches (configuration, layout configuration, block html output, translations, eav types, etc). I am no expert on Magento's caching mechanisms but here are a few random tidbits that might be helpful (maybe). (Also note that I am only familiar with Magento 1.3.x, not 1.4.x so things could have changed).
The caching is actually stored in the var/cache directory. There are a ton of directories in there (mage--0, mage--1, mage--2) and each directory has the cache files. Do a ls var/cache/mage*/* to see all the files.
Configuration - This source for the configuration is varied. Your app/etc/local.xml, and all of the config.xml files (that are in each module's etc dir) are combined together to make one big configuration object. Then Magento reads from the core_config_data table to update the configuration object. Then the configuration is written to a cache file so that next time a request is made it doesn't need to open a ton of config files and hit the database. Somehow this info gets stored in a bunch of files under var/cache. For some insight do a ls var/cache/mage*/*CONF*.
Layout - This is a lot like the configuration... there are a bunch of xml files in the app/design/frontendOrAdminhtml/yournamespace/layout/ directory and all these are merged into one layout configuration object, then cached in the cache directory.
Block HTML - The actual html generated by a block is cached. Each block is able to decide how long it is going to be cached.
Lastly, to (not really) answer your question about if the cache is per website or store, I can't really say since I haven't had the need to setup a multi-website/multi-store shop yet. It looks like there may be some store/website-specific files, but I can't see that they are really organized in a logical way. For example, in one of my instances I see a var/cache/mage--f/mage---LAYOUT_FRONTEND_STORE0_DEFAULT_BLANK_SEO file and a var/cache/mage--f/mage---LAYOUT_FRONTEND_STORE1_DEFAULT_BLANK_SEO... but then again, I only have one store configured and those two files have the same contents. Good luck with that!
You could also use some of the very great memcached analysis and reporting tools available
http://code.google.com/p/memcached/wiki/Tools
The best solution I have come up with is to use a two level cache.
Consult app/etc/local.xml.additional to see how to put memcached server nodes in there. Note that within the <servers> tag you will have to have tags like <server1> and <server2> encapsulating each memcached node's settings.
<cache>
<backend>memcached</backend>
<slow_backend>database</slow_backend>
</cache>
In this way all cache is shared.
To clear it the way I do it is to:
1. shut down apache
2. connect to mysql and connect to the magento db and run truncate core_cache; truncate core_cache_tag.
3. I then bounce the memcached nodes.
4. I restart apache but I keep it out of the load balancer until I have hit it at least once to generate the APC opcode cache. Otherwise the load can shot up through the roof.
This all seems extreme but I have found it works for me. Clearing cache using the backend is REALLY slow. I have around 100k entries in the core_cache table and close to 1 million entries in core_cache_tag. If I don't do it this way sometimes I get strange behavior.
Your Memcache configuration in ./app/etc/local/xml will dictate what Memcache is actually caching.
If you are only using a the single-level cache (without ), then Magento will store its cache (in its entirety) in Memcache.
HOWEVER without the slow_backend defined - it is caching content, without cache_tags - ie. without the ability to differentiate cache items
Eg. configuration, block, layouts, translations etc.
So, without the defined, you cannot refresh caches individually, in-fact, you'll almost always have to rely on "Flush Cache Storage" to actually see updates take effect.
We wrote a nice article here which covers your very issue - http://www.sonassi.com/knowledge-base/magento-knowledge-base/what-is-memcache-actually-caching-in-magento/
Memcached is a distributed memory caching system. It speeds up websites having large dynamic databases by storing database objects in Dynamic Memory to reduce the pressure on a server whenever an external data source requests a read. A Memcached layer reduces the number of times database requests are made.
The caching is actually stored in the var/cache directory. There are a ton of directories in there (mage--0, mage--1, mage--2) and each directory has the cache files. Do a ls var/cache/mage*/* to see all the files.
Configure Memcache Magento 2
Magento 2 also supports Memcached for caching objects but it isn’t enabled by default. You need to make simple changes to the $Magento2Root/app/etc/env.php file to enable it.
In env.php, you will see a large number of PHP arrays with different settings and configurations. Open the file in your favorite code editor and locate the following code:
array (
session' =>
'save' => 'files',
),
Modify this chunk as:
'session' =>
array (
'save' => 'memcached',
'save_path' => '<memcache ip or host>:<memcache port>'
),
Note that the default value for memcache ip is 127.0.0.1:11211. Similarly, the default value for memcache port is 11211.
For complete manual please look into it:
https://www.cloudways.com/blog/magento-2-memcached/
https://devdocs.magento.com/guides/v2.4/config-guide/memcache/memcache_magento.html

When is OpenAFS cache cleared?

Let's say I have a bunch of users who all access the same set of files, that have permission system:anyuser. User1 logs in and accesses some files, and then logs out. When User2 logs in and tries to access the same files, will the cache serve the files, or will it be cleared between users?
The cache should serve the files (in the example above).
How long a file will persist in the OpenAFS cache manager depends on how the client is configured, variables include the configured size of the cache, whether or not the memcache feature is enabled, and how "busy" the client is.
If OpenAFS memcache (cache chunks stored in RAM) is enabled, then the cache is cleared upon reboot. With the more traditional disk cache, the cache can persist across reboots. Aside from that key difference files persist in the cache following the same basic rules. The cache is a fixed size stack, recently accessed files stay in the cache and older files are purged as needed when newer files are requested.
More details are available in the OpenAFS wiki:
http://wiki.openafs.org/

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