How to Install CyberPanel with Redis and Memcached

Learn how to manually install CyberPanel on Ubuntu with a Redis and Memcached backend.

Code snippets and more at https://tonyteaches.tech/install-cyberpanel-ubuntu/

Check out my vlog channel @Tony Florida

#cyberpanel #redis #memcached

Music: Milos by Eveningland https://youtu.be/xVzOFBggR3o

#cyberpanel #redis #ubuntu

Redis Transactions & Long-Running Lua Scripts

Redis offers two mechanisms for handling transactions – MULTI/EXEC based transactions and Lua scripts evaluation. Redis Lua scripting is the recommended approach and is fairly popular in usage.

Our Redis™ customers who have Lua scripts deployed often report this error – “BUSY Redis is busy running a script. You can only call SCRIPT KILL or SHUTDOWN NOSAVE”. In this post, we will explain the Redis transactional property of scripts, what this error is about, and why we must be extra careful about it on Sentinel-managed systems that can failover.

Transactional Nature of Redis Lua Scripts

Redis “transactions” aren’t really transactions as understood conventionally – in case of errors, there is no rollback of writes made by the script.

“Atomicity” of Redis scripts is guaranteed in the following manner:

Once a script begins executing, all other commands/scripts are blocked until the script completes. So, other clients either see the changes made by the script or they don’t. This is because they can only execute either before the script or after the script.
However, Redis doesn’t do rollbacks, so on an error within a script, any changes already made by the script will be retained and future commands/scripts will see those partial changes.
Since all other clients are blocked while the script executes, it is critical that the script is well-behaved and finishes in time.

The ‘lua-time-limit’ Value

It is highly recommended that the script complete within a time limit. Redis enforces this in a weak manner with the ‘lua-time-limit’ value. This is the maximum allowed time (in ms) that the script is allowed to run. The default value is 5 seconds. This is a really long time for CPU-bound activity (scripts have limited access and can’t run commands that access the disk).

However, the script is not killed when it executes beyond this time. Redis starts accepting client commands again, but responds to them with a BUSY error.

If you must kill the script at this point, there are two options available:

SCRIPT KILL command can be used to stop a script that hasn’t yet done any writes.
If the script has already performed writes to the server and must still be killed, use the SHUTDOWN NOSAVE to shutdown the server completely.

It is usually better to just wait for the script to complete its operation. The complete information on methods to kill the script execution and related behavior are available in the documentation.

#cloud #database #developer #high availability #howto #redis #scalegrid #lua-time-limit #redis diagram #redis master #redis scripts #redis sentinel #redis servers #redis transactions #sentinel-managed #server failures

Ruth Nabimanya

1621219080

Redis vs. Memcached: 2021 Comparison

Redis stands for REmote DIctionary Server, created in 2009 by Salvatore Sanfilippo. Memcached, on the other hand, was created in 2003 by Brad Fitzpatrick. Both Redis and Memcached are:

NoSQL in-memory data structures
Written in C
Open source
Used to speed up applications
Support sub-millisecond latency

In 2014, Salvatore wrote an excellent StackOverflow post on when it makes more sense to use Memcached than Redis. In this post, we provide a current and detailed comparison between Redis and Memcached so that you can make an informed choice about their use in your application.

#redis #dba #database administration #memcached #database administrator #redis alternative #database comparison #redis news

Scottie Mills

1626800100

How to Install CyberPanel with Redis and Memcached

Learn how to manually install CyberPanel on Ubuntu with a Redis and Memcached backend.

Code snippets and more at https://tonyteaches.tech/install-cyberpanel-ubuntu/

Check out my vlog channel @Tony Florida

#cyberpanel #redis #memcached

Music: Milos by Eveningland https://youtu.be/xVzOFBggR3o

#cyberpanel #redis #ubuntu

Chet Lubowitz

1595855400

How to install PgAdmin 4 on CentOS 8

pgAdmin is the leading graphical Open Source management, development and administration tool for PostgreSQL. pgAdmin4 is a rewrite of the popular pgAdmin3 management tool for the PostgreSQL database.

In this tutorial, we are going to show you how to install pgAdmin4 in Server Mode as a web application using httpd and Wsgi module on CentOS 8.

Install pgAdmin4 on CentOS 8

**01-**To install pgAdmin4 on CentOS 8 we need to add an external repository, so execute the following command:

$ sudo rpm -i https://ftp.postgresql.org/pub/pgadmin/pgadmin4/yum/pgadmin4-redhat-repo-1-1.noarch.rpm

02- After we add the pgAdmin4 repository, let’s use the below command to install pgAdmin4 as server mode:

$ sudo dnf install pgadmin4-web

03- Before proceeding with the configuration of pgAdmin4, we need to install policycoreutils tool:

$ dnf install policycoreutils-python-utils

04- Once we done installing pgAdmin4, we need to configure the pgAdmin4 by setting up the initial pgAdmin user account

#databases #linux #ubuntu #install pgadmin4 #install pgadmin4 centos #pgadmin #pgadmin 4 install #pgadmin 4 install centos #pgadmin4 #pgadmin4 install centos

Brain Crist

1595372400

How to Install Android Studio on Ubuntu 20.04

1./ Install Android Studio Using APT

Method 1./ Install Android Studio Using APT

1- We need to add official repository to the sources list. Therefore, type the below command to add the Android Studio repository:

$ sudo add-apt-repository ppa:maarten-fonville/android-studio

02- Now let’s install Android studio and all the software dependencies as below.

$ sudo apt update
$ sudo apt install android-studio

Method 2./ Install Android Studio Using snap

We can install using the snap tool. So, use the below command to install Android Studio:

$ sudo snap install android-studio --classic

2./ Starting Android Studio

01- You can start Android Studio either by typing the command android-studio in your terminal or by clicking on the Android Studio icon (Activities -> Android Studio).