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implementing Object cache with APCu, Redis for wordpress memcached comparison

Update: I tried Redis on my previous server, it’s a little bit confused to go back. now I am trying APCu (because of its simplicity)
>> No need to communicate with another server.
>>NO TCP Connection (to PHP & MySQL)
>> ACpu stores in php shared memory (no separate memory allocation needed, this can cause memory -hog I need to increase PHP memory size and figure out how much MySQL using)

ACPU Installation

from repository
check your distribution version
lsb_release -a
Description: Ubuntu 18.04.1 LTS

step 1: 
sudo apt-get install php7.2-apcu -y
step 2:
nano /etc/php/7.2/mods-available/acpu.ini
add the following adjusting memory size
extension=apcu.so
apc.shm_size = “50M”
check php enabled modules by
php -m
restart
step 3:
service php7.2-fpm restart
step 4:
go to w3tc >>general settings>> object cache>> Apc/apcu.

Installing Redis from source

Latest version 4.0
http://download.redis.io/redis-stable.tar.gz
redis as server
Using Redis as an LRU cache
Installing from source & compile at the server
sudo apt-get update
sudo apt install build-essential
cd /tmp
wget http://download.redis.io/redis-stable.tar.gz
tar xzvf redis-stable.tar.gz &&  cd redis-stable
make && make install
cleaning temdirectory
cd..

working with redis configuration file

sudo mkdir /etc/redis &&  cp redis.conf /etc/redis/
sudo nano /etc/redis/redis.conf
maxmemory 128mb
maxmemory-policy allkeys-lru
supervised no (change)
supervised systemd
working directory
dir ./
change to
dir /var/lib/redis
Create Redis systemd Unit File
sudo nano /etc/systemd/system/redis.service
copy & paste the below code

[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always

[Install]
WantedBy=multi-user.target

save the file by CTRL+X and type and hit enter.

Creating User /group /directories and permissions

sudo adduser –system –group –no-create-home redis &&  mkdir /var/lib/redis && chown redis:redis /var/lib/redis && chmod 770 /var/lib/redis

start

sudo systemctl start redis

stop

sudo systemctl stop redis

restart

sudo systemctl restart redis

Enable Redis on every Bootup

sudo systemctl enable redis
testing:
netstat -lntp to know all listening ports
# redis-cli
127.0.0.1:6397>>ping
you will get pong
Redis configuring with PHP
install the Redis Object Cacheplugin.
why Redis among Memcached and php apcu?

php 7 install redis extension

apt-get install php-redis
check redis module or not by typing
php -m | grep redis
PHP Warning: Module ‘redis’ already loaded in Unknown on line 0
redis
supports PHP 7 then don’t go for manual installation.
memcached storage is low,
php acp dead and rebuild as APCu.  store cache in the PHP shared memory (memory-hog >>opcode cache memory, php process memory may unstable>> due to high memory allocated to a single php process when you increase over all php memory)
Installing from ubuntu repository
apt-get install redis
apt-get install php-redis
Quick & easy but not the latest version.

Enable Redis object cache in w3 Total cache

Performance (w3tc)>> General settings>> page cache>>

  1. Disc basic
  2. Disc enhance
  3. Php Apcu
  4. Redis  (it will available once you load redis PHP extension)
APcu vs Memcached vs Redis
APCu
Does not share the cache with other servers but is faster (maybe)
single machine.
nano /etc/php/7.0/mods-available/apcu.ini
extension=apcu.so
apc.shm_size = “40M”
nano /etc/php/7.0/mods-available/redis.ini
apc
don’t disable timestamps. it caches all unnecessary PHP file from /wp-includes and wp-admin/
don’t set large amount memory.
validate settings should be low.
Conclusion: i have tried both Apcus and Redis in the past. installed Memcached on the test server as of far i don’t remember about Memcached. its a tie between redis and Apcus. (both Memcached & redis are distributed but Apcu works only for local machine)
Reference:
https://guides.wp-bullet.com/install-redis-object-cache-for-wordpress-php-7-on-ubuntu-16-04/
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04

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