Background (Skip this part if you want)
Feel free to skip over this part if you choose, it's just some background for those who want to better understand the problem
At the beginning of one action on my site, I kick off several asynchronous operations. The action returns before the operations are complete. This is what I want. However, the View that gets loaded by this action invokes several other actions in a different controller. Some of these actions rely on the results of the async calls from the first page, so I need to be able to wait on the async calls to finish from the other controller. I thought about just using Session to store the WaitHandles, but as WaitHandles aren't serializable, I obviously can't do that.
Short version:
I need to be able to store an async WaitHandle object somewhere from one controller, such that it can be reliably retrieved in a different controller. These WaitHandles also need to be user-specific, but I can handle that part. Just don't list an option that would make doing that impossible.