But that does not make the compiler thread safe. 'Unix way' to compilation: possibly parallel compile activities by running multiple compiler instances as prog

But that does not make the compiler thread safe. 'Unix way' to compilation: possibly parallel compile activities by running multiple compiler instances as programs 'ASDF way' to compilation: compile multiple files in a serialized fashion using one Lisp image for compilation To run multiple compile activities inside one Lisp image, one would require that something like the file compiler is thread safe and corresponding stuff implemented by the program in the compile-time environment is thread-safe, too.