Runspace pools may cause memory leaks, at least in tested PowerShell v5, v6. PowerShell v2 does not have this issue.
The below scripts repeat a similar job infinitely in a loop. Run them and watch the printed application handle counts and memory sizes. Stop scripts manually by Ctrl+C or close their PowerShell consoles.
The script Test-LoopRunspacePool.ps1 uses runspace
pools for [PowerShell] sessions. It calls Close() for pools and shows the
leaks, i.e. handle and memory numbers constantly grow over time.
The script Test-LoopPowerShell.ps1 uses [PowerShell]
sessions without runspace pools. It does not show leaks, i.e. handles and memory
numbers stay within some reasonable range. Thus, avoiding runspace pools is one
way to work around the leaks.
Workaround
In many cases, calling Close() or Dispose() amount to the same thing but not with a RunspacePool. You need to call Dispose()
Thus, calling Dispose() instead of Close() for runspace pools solves the issue.
See Test-LoopRunspacePool.workaround.ps1.