Having Memcache and Memcached installed and enabled at the same time

joomlamemcachememcachedphp-memcachedphpbb

Can I use both Memcache and Memcached php extensions on the same server at the same time? Just to be clear so you dont misunderstand what I mean by this question, here is my scenario: I have both Joomla and phpbb for my website. Joomla provides support for both memcached and memcache where as phpbb only provides support for memcache. So I am planning to do this:

1) Install memcached server: apt-get install memcached

2) Install php-memcache to use for phpbb: apt-get install php5-memcache

3) Install php-memcached to use for Joomla: apt-get install php5-memcached

My questions are:

Is it okay to have both memcache and memcached extensions installed
and enabled where each of these are used by different php applications at the same time? Would
this conflict in any ways?
When I set the memory limit for the memcached server to 512M in
/etc/memcached.conf, does it mean that this memory limit is going
to be shared between both memcache and memcached extension? This
shouldnt be a problem if say memcache uses more memory than
memcached or vice versa? Do they both play nice to each other?
In the scenario like this, should I try to give preference to only 1
php extension (like either memcache only in my case) to keep things simple
without conflicts between the two or it shouldnt matter. What I mean
is, if you say it is okay to use both (for Q1), then out of
professional practice, even if both can be used at the same time,
should I still try to use the same php extension for both Joomla and
phpbb if possible to minimize headaches? Would that make difference in any ways?

Best Answer

@Alin Andrei posted the right answer for this question. I am quoting him here since the answer is hidden in the comments. The credit goes to him:

1. memcache and memcached are two separate extensions that do not depend on each other so yes you can have them both installed. 

2. if both extensions use the same memcached server, then yes the memory is shared between them, you can keys from both extensions but only the size of 512 

3. if you can use the same extension on both apps then use only one to simplify the complexity you have. You could both of them as well, i dont think it will increase in size if you use both of them

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Linux PHP Memcached – Memcache vs Memcached: Key Differences Explained

The short answer: Either one is what you are looking for, but my first choice would be memcache (the first one you listed), purely based on its correct use of nomenclature.

Now here's how I came to that conclusion:

Here is a quick backgrounder in naming conventions (for those unfamiliar), which explains the frustration by the question asker: For many *nix applications, the piece that does the backend work is called a "daemon" (think "service" in Windows-land), while the interface or client application is what you use to control or access the daemon. The daemon is most often named the same as the client, with the letter "d" appended to it. For example "imap" would be a client that connects to the "imapd" daemon.

This naming convention is clearly being adhered to by memcache when you read the introduction to the memcache module (notice the distinction between memcache and memcached in this excerpt):

Memcache module provides handy procedural and object oriented interface to memcached, highly effective caching daemon, which was especially designed to decrease database load in dynamic web applications.

The Memcache module also provides a session handler (memcache).

More information about memcached can be found at » http://www.danga.com/memcached/.

The frustration here is caused by the author of the PHP extension which was badly named memcached, since it shares the same name as the actual daemon called memcached. Notice also that in the introduction to memcached (the php module), it makes mention of libmemcached, which is the shared library (or API) that is used by the module to access the memcached daemon:

memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

This extension uses libmemcached library to provide API for communicating with memcached servers. It also provides a session handler (memcached).

Information about libmemcached can be found at » http://tangent.org/552/libmemcached.html.

In summary, both are functionally the same, but they simply have different authors, and the one is simply named more appropriately than the other.

Ubuntu – Setting up memcached/memcache with Php on Ubuntu 10.10

Memcached is the name of the Memcache daemon.

Using Memcache with PHP you are able to store PHP sessions in memory rather than in separate files on disk. This results in many times faster session management. This is especially useful when you've set up a load balancer and a few web app servers behind it but you plan to share sessions for each of your servers. You can run memcache on one of your servers or a separate server and make all your servers cache to the one running Memcache.

To get started:

sudo apt-get install memcached

Go through the config file in /etc/memcached/memcached.conf and see if the defaults are good for you.

Now install php's memcache client

sudo apt-get install php5-memcache

When asked, enable session handler support. Also, add

extension=memcache.so

and

session.save_handler = memcache
session.save_path = "tcp://10.0.0.1:11211"

to your php.ini (probably in /etc/php5/apache2/php.ini). Change the ip to your memcache server address or to 127.0.0.1 if you run it locally.

Start the service with

/etc/init.d/memcached start

Before installing anything, you really should read up on what the package does otherwise you will not be able to get the most out of it.

Best Answer

Related Solutions

Linux PHP Memcached – Memcache vs Memcached: Key Differences Explained

Ubuntu – Setting up memcached/memcache with Php on Ubuntu 10.10

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