Nothing inherent, no. Hastings discusses this is the talk: short version is that having a GIL gets python a fairly simple, straightforward implementation (also

Nothing inherent, no. Hastings discusses this is the talk: short version is that having a GIL gets python a fairly simple, straightforward implementation (also for extension authors); not having it requires a lot of work to achieve comparable performance. This is why so many interpreted languages use a GIL (like Ruby). No language requires it, it just makes the language much easier to develop and extend. Implementations like Jython that don't have one, don't because the hard work to not have one is already done in the VM. It only took him about a week to remove the GIL (and the talk includes the steps); all this work is making a GIL-less python work as well as one with a GIL.