In PR #7131 (https://github.com/apache/cloudstack/pull/7131) I have
proposed to normalize ACS's loggers, and more importantly, upgrade the
library log4j to log4j2 version 2.19.
Log4j2 has a lot of features that could offer benefits to ACS:
* Async Loggers - performance similar to logging switched off
* Custom log levels
* Automatically reload its configuration upon modification without
loosing log events during reconfigurations.
* Java 8-style lambda support for lazy logging (which enables methods
to be executed only when necessary, i.e.: the right log level)
* Log4j 2 is garbage-free (or at least low-garbage) since version 2.6
* Plugin Architecture - easy to extend by building custom components
* Log4j 2 API is separated from the Log4j 2 implementation.
* Log4j 2 API supports more than just logging Strings: CharSequences,
Objects and custom Messages. Messages allow support for interesting
and complex constructs to be passed through the logging system and
be efficiently manipulated. Users are free to create their own
Message types and write custom Layouts, Filters and Lookups to
manipulate them.
* Concurrency improvements: log4j2 uses java.util.concurrent libraries
to perform locking at the lowest level possible. Log4j-1.x has known
deadlock issues.
* Configuration via XML, JSON, YAML, properties configuration files or
programmatically.
In my personal experience using it in some other projects, log4j2 is
easier to work with in general, has better performance, and is an active
project with constant development, innovation, and security patches.
Moreover, it is under a well known and trusted open source organization.
The change proposed in PR #7131
(https://github.com/apache/cloudstack/pull/7131) has been tested and
validated in a lot of different scenarios by different people. We have
already tested the logging in the management server, usage, agents, and
system VMs; all of that using KVM and Vmware + Veeam. Most feature sets
were tested, create/delete/update VMs, disks, cresate snapshots, user
management and so on.
The proposal has been discussed since January, 2023 in the PR
(https://github.com/apache/cloudstack/pull/7131), but I have been
requested to bring it to the mailing list. I would love to hear your
opinions on it, also, any reviews to the PR would be welcome.
