For Perl, Mojolicious seems to be the most popular nowadays:

• Mojolicious docs
• Mojo::IOLoop (Minimalistic event loop) by Sebastian Riedel
• Mojolicious by Sebastian Riedel
• Mojolicious::Lite by Sebastian Riedel
• Minion Job queue by Sebastian Riedel is also worth a look - as noted by Corion below (update)

• Re: IO::Socket tutorial by haukex (2020) - compares select, IO::Select, POE, Mojolicious
• Re: IO::Socket tutorial by haukex (2020) - a complete example with Mojo::IOLoop and Mojo::IOLoop::Stream::Role::LineBuffer

• Re: IO::Socket simple server by haukex (2023) - Mojo::IOLoop can be used independently of the Mojolicious framework to write TCP servers
• Re: Using AnyEvent to create a TLS server by haukex (2023)
• Re: Socket buffer errors by haukex (2023) - mentions many different ways he's written a Web server before settling on Mojolicious
• haukex's scratchpad - see "My Mojolicious posts" section