As Dinnerbone tweeted, he changed the Hoppertimings in the latest Snapshot (https://twitter.com/Dinnerbone/status/307446745594478592).
After a short test I found out, that they now update every 9 gameticks (4.5 redstoneticks), instead of every 8 gameticks (4 redstoneticks), which makes it incredibly difficult to time hoppers.
For example if you want to get one item out of a hopper you now would have to depower it for exactly 4.5 redstoneticks wich is not really possible, or only possible with a pretty big circuit. You can't just depower it for 4 redstone because you would get 0 to 1 items and neither for 5, because you would get 1 to 2 items (It's unreliable).
Furthermore it doesn't make sense that a redstoneitem (like the hopper) updates every 4.5 ticks (wich is not an integer) instead of every 4 ticks (or another whole number)
After a look into the sourecode my assumption, that it's a bug got confirmed, because after every time, the hopper takes an item, it set's the cool-down to 8. The bug is that the algorithm checks if the cool-down is greater than zero. So eight ticks after the last update the cool-down will reach 0, but the hopper won't update until the next tick, wich makes it a total of 9 ticks in between 2 hopper updates instead of the wanted 8.
Comments
kumasasa
This is very important, IMO. I had a machine that halved (rounding down) the amount of a specific item put in into points. And it did so as fast as the hoppers could send out items. So input 64 coal in the coal specific machine and get 32 points to your specific scoreboard, yet now, the more realistic situation is: Put in 64 coal and get 36 points. This is highly concerning. It uses a clock that repeats every 8 Redstone Ticks (16 In-Game) which was perfect for the duration of a hopper sending out 2 items, but now, with a need for 9 (18), an odd number of Redstone ticks, it is rendered useless and not fixable within the space provided. I have tried decreasing the clock by a tick (which is doubled by the clock) which results in 28 points being given. This proved the need for an additional redstone tick (which is the result of two half ticks). So, not to drone on anymore, I believe this is an important issue to fix in the future.
Nathan Adams
Please do not mark unreleased versions as affected. You do not have access to this yet.