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WpW: Object Cache Support in LSCache

February 7th, 2018 by Lisa Clarke LSCache 29 Comments

Welcome to another installment of WordPress Wednesday!

Today’s topic is: Object Cache Support in LSCache

Disclaimer: The information contained in this post is accurate for LSCWP v4.5.0.1 [release log]. If you are using a newer version of the plugin, some details may have changed. Please refer to our documentation for the latest!

You asked for it, and we delivered. LiteSpeed Cache for WordPress supports Object Cache!

What is an Object Cache?

An object cache stores the results of expensive and/or frequent database queries in a way that makes them easy to retrieve, and eliminates the need for repeated access to the database. Object caching greatly reduces the time it takes to retrieve query results.

For example, WordPress stores your site’s options in the database. Site options include things like the site’s name and URL. Every time WP assembles a page for a visitor, it is necessary to access the database to read the site options. As you can imagine, these repeated queries for the same information represent wasted resources. With an object cache, you can query the database once, and save the results for a set period of time. During that time, whenever a page must be assembled, WordPress can get the site information from the object cache. Accessing object cache is a much less resource-intensive prospect than accessing a database.

Some queries are time-consuming, and other queries are repeated frequently. Both of these scenarios can be improved by storing the query results in object cache.

Note: If you have a site that is fully-cached by LSCWP, object cache won’t be invoked very often. Object cache is only necessary when WordPress is building a page through PHP. If PHP is not being called (and minimizing PHP usage is the goal with LSCache, after all) then there are no queries to process and therefore nothing to look up in object cache.

How to set up Object Cache Support

LSCWP doesn’t provide object caching directly. Rather, it supports your use of an external object cache such as Redis, Memcached or LiteSpeed’s drop-in Memcached replacement, LSMCD. Setting up object cache systems is outside of the scope of this tutorial, but you can find some useful information via the product links above or by visiting our documentation site.

So, assuming you are already using one of these object caching methods, you can set up LSCWP support in the Cache Settings tab.

Navigate to LiteSpeed Cache > Cache > Object. You will need to give LSCWP some parameters, including where your Redis, Memcached or LSMCD lives, which objects you’d like to have cached, and how long you want objects to remain in cache, among other things.

LSCache Object Cache Settings

Object Cache

This entire integration is disabled by default. Select ON to enable it and then configure it via the settings, as described below.

Status

This is an informational area to let you know the status of your external object cache. If you are getting errors here, please see How to Debug your Object Cache Setup.

Method

Choose Memcached if using Memcached or LSMCD. Choose Redis if using Redis.

Host and Port

These settings refer to the hostname (or IP address) and port number used by your object cache. The default values of localhost and 11211 should work fine for you, if your cache is set up via a TCP connection. If you are using a UNIX socket, Host should be set to /path/to/memcached.sock (substitute the actual path used for your installation) and Port should be set to 0.

Default Object Lifetime

Choose a TTL for items stored in the object cache. We recommend using a relatively short time in order to avoid stale results. Default is 360 seconds.

Username, Password, and Redis Database ID

These settings may or may not be applicable, depending on your object cache setup. If you have SASL installed, fill in the appropriate credentials. If you are using Redis, enter your database ID. These measures will prevent cross-contamination in situations where multiple sites share one object cache.

LSCache Object Cache Settings

Global Groups

This is a list of groups that you want to cache at the network level. By default:

users
userlogins
usermeta
user_meta
site-transient
site-options
site-lookup
blog-lookup
blog-details
rss
global-posts
blog-id-cache

Do Not Cache Groups

These are groups that you do not want to include in object cache. By default:

comment
counts
plugins

Persistent Connection

If enabled, the connection is kept alive in order to make Memcached faster. This is set to ON by default.

Cache WP Admin

If enabled, WordPress admin will be sped up, but at the risk of occasionally retrieving stale data from the object cache. This is set to ON by default.

Store Transients

When Cache WP Admin is set to OFF, transients have nowhere to go. Without transients, you don’t receive server status notices (such as XXXX has been completed successfully.). If you have disabled Cache WP Admin, then you can use Store Transients to get server notices. This is set to ON by default.

Why do You Need LSCache for This?

You may be wondering: what is the point of setting up object cache support in the LSCache plugin?

So here’s the thing: you can’t use object cache without telling WordPress how to handle it. You need a plugin for that. You can install a single-purpose object cache plugin, or you can let LSCache facilitate the relationship between your object cache and WordPress.

It comes down to this: would you rather install several plugins with many different interfaces to handle all of your optimization needs? Or would you rather have one optimization plugin that can handle it all? If you like the second option, then LSCache is your solution!

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Have some of your own ideas for future WordPress Wednesday topics? Leave us a comment!

Don’t forget to meet us back here next week for the next installment. In the meantime, here are a few other things you can do:

Subscribe to the WordPress Wednesday RSS feed
Download LiteSpeed Cache for WordPress plugin
Learn more about the plugin on our website

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This content was last verified and updated in April of 2023. If you find an inaccuracy, please let us know! In the meantime, see our documentation site for the most up-to-date information.

Tags: object cache, wordpress, wordpress wednesday

Categories:LSCache

Comments

max November 18th, 2022
hi, is it reasonable to use both memcached and redis with LireSpeed Cache plugin? if yes then how? there is only Method swither – either Memcached or Reddis
BUT in Status field i see:
Memcached Extension: Enabled
Redis Extension: Enabled
Connection Test: Passed Learn More
Reply
- Lisa Clarke November 18th, 2022
  That status indicates that you have both PHP extensions, but you can’t actually use both at the same time. You should just pick one and stick with that.
  Reply
  - Rolf September 3rd, 2024
    So if you have the choice between Memcached and Redis, which one would you recommend? Which one is fastest for WP object caching with lscache? And what about socket if available? Is that faster than port or no difference?
    Any advise is much appreciated 🙂
    Reply
    Lisa Clarke September 4th, 2024
    Hi, Rolf. I asked the support team, and they said it only matters in extreme cases. If you’ve got tens of thousands of queries per second, redis is faster than memcached, and socket is faster than port. But under the load of a typical WP site, it shouldn’t make any difference. Hope this helps!
    Reply
Razeakhar April 12th, 2022
Great article.
I have this erroe ” You should use a persistent object cache ” and easily solve it.
Thanx again ❤️
Reply
Orlando Fernando Marconi December 17th, 2021
Hi!
Is there any place that I can better filter these groups and understand what each one does?
users
userlogins
useremail
userslugs
usermeta
user_meta
site-transient
site-options
site-lookup
site-details
blog-lookup
blog-details
blog-id-cache
rss
global-posts
global-cache-test
comment
counts
plugins
wc_session_id
The names look very obvious, but I wanted to read some documentation about it and other groups that I can add, or are there all?
Thanks for the support via commets
😉
Reply
- Lisa Clarke December 17th, 2021
  We use WordPress’s own Object Cache functions, and those groups are standard WP groups. I looked through the WordPress official docs, but couldn’t find any reference as to what they mean. Looking at the WP github code, we’re assuming that users, userlogins, email, slugs, metadata are for caching queries related to users. site- groups refer to individual sites, and blog- are for multisite setups. wc is for WooCommerce. Other than that, I’m afraid we don’t have any insight.
  Reply
  - Orlando Fernando Marconi December 19th, 2021
    No problem!
    This is already very useful!
    Thanks!
    Reply
Orlando Fernando Marconi December 15th, 2021
Hi!
If I’m using REDIS, can I completely disable MEMCACHED right?
How can I do this? What is the command?
Sometimes when I’m watching the TOP command, a Memcache process appears, I want to disable it.
Thanks!
Reply
- Lisa Clarke December 16th, 2021
  Yes, you can disable it. Here’s how:
  systemctl stop memcached systemctl disable memcached systemctl mask memcached
  Reply
Peter November 3rd, 2021
Is it okay if the default object lifetime of redis is increased? Let’s say to 1 hour?
Reply
- Lisa Clarke November 3rd, 2021
  I don’t see any reason why that, technically, can’t be done. But I can’t really say whether that is a good idea or not. It probably depends on the nature of your site, how often content changes, etc. I’d say this is more of a question for a redis forum.
  Reply
Morteza August 17th, 2021
how can i use object cache with redis cluster ?
Reply
- Lisa Clarke August 19th, 2021
  I’ve asked the team, and while we don’t have experience with redis cluster, we’re pretty sure setup in the LSCWP plugin should be the same as standalone redis.
  Reply
rakyatnesia June 26th, 2021
hi i using redis plugin and LScache , should i uninstal redis plugin when i turn on redis setting on LScache ?
Reply
- Lisa Clarke June 28th, 2021
  Yes. You can only use one object cache plugin at a time, so you can either use the redis plugin, or you can set up redis in LSCache, but not both.
  Reply
Ara Komputer September 19th, 2020
Hi Lisa
can you tell me how to obtain path to ” $address = ‘/path/to/memcached.sock’ ; // set the address here” or path to memcached.sock ?
In my Phpinfo information ,
memcached
memcached support enabled
Version 3.1.5
libmemcached version 1.0.18
SASL support yes
Session support yes
igbinary support no
json support no
msgpack support no
Reply
- Lisa Clarke September 19th, 2020
  Hi, Ara. That is the path that was configured when you set up Memcached. (More info)
  If you have root access you can run the following command: ps -aux | grep memcached | grep -v grep
  If should output something like this:
  site_user 947 0.0 0.0 366536 3924 ? Ssl Sep04 8:28 /usr/bin/memcached -u site_user -p 11211 -m 64 -c 1024 -s /var/www/html/memcached.sock -a 0770
  If you don’t have root access, you will have to ask your hosting provider for help.
  Hope this helps!
  Reply
Gopal Thakur March 23rd, 2019
Dear Sir
I am using these plugins but suddenly the following problems have come up, how to correct it. I’m not able to open the WordPress admin dashboard.
“Can NOT find LSCWP path for object cache initialization in /home/merasharebazaar/public_html/wp-content/object-cache.php
Warning: Cannot modify header information – headers already sent by (output started at /home/merasharebazaar/public_html/wp-content/object-cache.php:36) in /home/merasharebazaar/public_html/wp-includes/pluggable.php on line 1251
Warning: Cannot modify header information – headers already sent by (output started at /home/merasharebazaar/public_html/wp-content/object-cache.php:36) in /home/merasharebazaar/public_html/wp-includes/pluggable.php on line 1254”
regards
Gopal
http://www.merasharebazaar.com
Reply
- Lisa Clarke March 25th, 2019
  Please create a ticket through our client area or by sending email to support@litespeedtech.com. Thanks!
  Reply
Ryan March 13th, 2019
Thank you for this tutorial. I managed to install redis and predis on my dedicated server ( CloudLinux 6, Litespeed Webserver Enterprise” while creating two instances as a start. I opt to utilize dedicated instance per cPanel account on the server to prevent cross contamination. The connectivity tests for both instances were successful. but I’m stuck at the the database ID and password i must specify on LS wordpress cache configuration page – I understand that the ID must be between 0 and 16 but is this limitation per cPanel account and so per Redis instance or is it on the whole server – as for the password was i supposed to specify it during Redis installation or on redis.config “that i am being able to find” before pasting it into LSWC. My apologies for these questions but i am new to Redis.
Reply
- Lisa Clarke March 14th, 2019
  Hi, Ryan. We see you already created a ticket about this. Shivam has responded to you there 🙂
  Reply
John Wuethrich October 26th, 2018
I cant get it to turn on or even show its tested. If i uninstall and reinstall plugin the connection test works for the first view but i have sockets enabled so the settings it tries arnt right. If i enter the right ones and hit save it reloads to totally blank fields where i had entered settings. Connection test “not available”.
nc -U /path/sockname.socket works so it apears to be an issue with the plugin, any suggestions? is it possibly something with openbase dir (along the lines of the server cant access the path?) Ive tried ln -s and moving it one step bellow doc root but that didnt seem to change anything.
Reply
- Lisa Clarke October 26th, 2018
  Hmmm, our support team will need to look a little more closely at your setup. Please create a ticket through our client area or by sending email to support@litespeedtech.com. Thanks!
  Reply
  - John Wuethrich October 26th, 2018
    im running olsws… does that change anything or is this something they would want to see anyway?
    its bizarr i got the memcached php test file working so now i know the socket is good and accessible via php but nothing on the advanced tab sticks around after hitting save. page refreshes and its blanked out. I guess i should set up logging and see if that tells me anything
    Thanks!
    Reply
zakki March 28th, 2018
Hi, I am using LS Cache version v2.1.1.1. I can’t found Object Cache in my advanced tab, only 2 option in there : Improve HTTP/HTTPS Compatibility and Instant Click. Where is Object Cache option location?
thanks
Reply
- Lisa Clarke March 28th, 2018
  Hi, Zakki. It sounds like you are on WordPress multisite? If so, you can find the Object Cache settings in the Advanced tab at the network level. It can’t be configured from within an individual site.
  Reply
Steve February 7th, 2018
Forgive the cache newbie question, but can you explain where the list of groups is coming from, and how do I know they are correct for my site?
Reply
- Lisa Clarke February 7th, 2018
  Our object cache implementation uses WordPress’ object cache interface and then stores the results with your Redis or Memcached backend.
  Without getting into a whole lot of technical details, I can tell you that WP itself comes up with the group list. This is one of those things where the default value is fine for 99% of the people who use it, and if you don’t know what it is, then you shouldn’t need to change it.
  In the event that you do want to know more technical details, you can take a look at this page of the WordPress Codex where they describe the elements of their object cache interface, including the purpose of groups. There is a link there to their source code, if you really want to dig into it.
  I hope that clears it up a little bit. If not, let me know!
  Reply