[freshhawk]

I'm pretty sure that the alts! block is absolutely necessary otherwise you will deadlock after 10 files (your channel buffer size) because nothing else is taking from upload-chan or signing-chan.

Wouldn't a pipeline be a better solution to this? Taking and throwing away the values from a channel just to trigger a transducer that puts the value in another channel as a side effect is a strange way to do things.

Also a simple println test will show that the transducer function is triggered when you put on the channel rather than when you take.