first write: T
after first write: queue size 1
second write: T
after second write: queue size 2
before completion: completed 0
complete first: queue size 2, delay elapsed F
finish first: T
after completion: queue size 1
set limit 2: T
set limit 0: T
before expiration: queue size 1, completed 1
complete second: queue size 1, delay elapsed T
file done: queue size 0, completed 2
done: queue size 0
