Switch to Garbage Collection

[ecton]

In thinking of how to make Muse truly safe from malicious code, reference cycles will always be a problem for causing memory leaks.

The only real solution is going to be to adopt a garbage collector. There are some great crates out there, but sadly many are very opinionated about what is and isn't supportable or safe.

We either need a mechanism for concurrent garbage collection or we will need an easy way to convert values from one garbage collector to another to allow passing values between different Vms.