NIOSingletons
SwiftNIO provided singleton resources for programs & libraries that don’t need full control over all operating system resources. This type holds sizing (how many loops/threads) suggestions.
enum NIOSingletons
Users who need very tight control about the exact threads and resources created may decide to set NIOSingletons.singletonsEnabledSuggestion = false
. All singleton-creating facilities should check this setting and if false
restrain from creating any global singleton resources. Please note that disabling the global singletons will lead to a crash if any code attempts to use any of the singletons.