> The earliest JVMs weren't really thread safe at all but machines were single core so it didn't matter, you could just cooperatively multi-task. In the 90s we

> The earliest JVMs weren't really thread safe at all but machines were single core so it didn't matter, you could just cooperatively multi-task. In the 90s we didn't have multiple cores but we had multiple CPUs. I started using java in '96 on a 2 CPU SPARC and the lack of real thread support was limiting. When green threads was dropped in favor of real (OS) thread support there was much rejoicing. I worked primarily in server performance back in those days. > Virtual threads are M:N threading. Solaris had M:N threads early on but it also was dropped.