The former implementation had 5 threads permanently spinning fast
(10ms sleep) while waiting for a REST connection to process.
This causes higher load in general and it breaks systems where
"Turn on PowerShell Script Block Logging policy" is enabled,
because then each PS statement including Start-Sleep is logged -
resulting in 500 event log entries per second. It's a suggested
setting in some hardening guidelines.
We can easily replace the Queue with a BlockingCollection backed
by a ConcurrentQueue, which has the built-in feature to sleep until
there are new items. Now the REST API threads consumes zero CPU time
while waiting.
Feature: Rework IMC menu and extend feature set
Reworks the menu structure of the Icinga for Windows Management Console and makes it the default when running the command `icinga`.
For developers you can use `icinga -Shell` to receive the Icinga shell as before. In addition improves error handling of IMC, by caching all `Errors` and `Warnings` during action execution, printing them afterwards.
Fix: Icinga Managed User lookup time
Fixes the lookup time if a user is managed by Icinga for Windows or not in large Active Directory environments, by using \`Get\-LocalUser\` instead.
This Cmdlet is available starting with PowerShell 5.0 and later and only required in general for running Icinga for Windows in JEA context. As JEA is only supported starting with PowerShell 5.0 or later, this will not cause any problems.
In case the command is executed on an older system without the \`Get\-LocalUser\` Cmdlet available, Icinga for Windows will handle all users tested with the new implementation as \`not\` managed by Icinga for Windows.
