Man pages matching name anyevent::processor::watcher in section 3pm:

AnyEvent::Processor::Watcher.3pm.en	debian 10 / libanyevent-processor-perl
AnyEvent::Processor::Watcher.3pm.en	debian 11 / libanyevent-processor-perl
AnyEvent::Processor::Watcher.3pm.en	debian 12 / libanyevent-processor-perl