Investigate potential memory leak associated with the use of deferred nodes.

[willow-ahrens]

Deferred nodes now hold copies of the actual inputs, for use in the galley scheduler. If we hold on to the program with deferred nodes, we may introduce a memory leak as the inputs cannot be garbage collected.

[wraith1995]

Does Julia have weak references? That would be the typical solution to this problem.

[willow-ahrens]

I think the main issue is that we still hold on to the program, and the inputs are now pasted into the program. The inputs currently remain reachable as the programs are keys in the compiled code cache.