Java has gone full circle.

Java had green threads in 1997, removed them in 2000 and brought them back properly now as virtual threads.

I'm kinda glad they've sat out the async mania, with virtual threads/goroutines, the async stuff just feels like lipstick on a pig. Debugging, stacktrackes etc. are just jumbled.

In Rust debugging and stacktraces are perfectly fine because async/futures compile to a perfect state machine.

I don't think comparing 97's green threads to virtual threads ever made sense.

Like their purpose/implementation everything is just so different, they don't share anything at all.

Java didn't really "sit it out". It launched CompletableFutures, CompletionStages, Sources and Sinks, arguably even streams. All of those are standard library forms of async programming. People tried to make it catch on, but the experience of using it, The runtime wrapping all your errors in completion exceptions, destroying your callstacks, just made it completely useless.