The thing really needed is a "Collect with timeout" function. Something like "Garbage collect now, but abandon the job in a consistent state if X milliseconds have passed".
(Perhaps even some other event. Like "Do GC until a File IO operation finishes")
I think this is referred to as Incremental GC, and runtimes like Spidermonkey, V8 and Lua have it. I'm not sure whether there's any hope of getting it for .NET or whether Java has one though.
(Perhaps even some other event. Like "Do GC until a File IO operation finishes")