Yeah, this is a real problem. The PG gem, for example, uses some global variables.

IMHO the only way to do it is to add incremental parallelism which leaves the GIL in place. Racket has already shown a solid path here.

Guilds would have a major performance problem: can't allocate objects without GIL. It's also a tricky mental model and requires invasive changes to existing Ruby code to handle frozen objects.

Places don't share a heap so they don't need the GIL to allocate objects and have independent GC rather than global GC. It's a model which fits better with existing Ruby code. The GVL can be relaxed while executing Ruby and grabbed by native methods.

WDYT?