[MC-8631] Hopper Loop starts skipping Hoppers Created: 28/Jan/13  Updated: 03/May/15  Resolved: 03/Feb/13

Status: Resolved
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Snapshot 13w04a, Snapshot 13w05a
Fix Version/s: None

Type: Bug
Reporter: Dennis Müller Assignee: Unassigned
Resolution: Duplicate Votes: 1
Labels: hopper, redstone
Environment:

Windows 7 64Bit, Java 7.0.90.5 64Bit


Attachments: PNG File Setup 1.png     PNG File Setup 2.png     PNG File Setup 3.png     PNG File hopper_loop_bug_setup.png    
Issue Links:
Duplicate
duplicates MC-8457 Chest sometimes doesn't activate Reds... Reopened
CHK:
Confirmation Status: Confirmed
Game Mode: Creative

 Description   

I created a loop of 6 hoppers, all attached to the one next to them and put one item in this loop. Next to each hopper is a comparator to display where the item currently is.
A block with redstone on it is on top of each hopper to start and stop them giving the item around. (See screenshot for setup)

The goal was to create a simple and compact clock, which can be locked on one position by a lever.
This works for some time, but after a few uses, it starts randomly skipping hoppers until the item only gets swapped between two hoppers, even if they aren't next to each other.
Re-placing the hoppers will temporarily fix this.



 Comments   
Comment by malacvadasz [ 22/May/13 ]

I set up a lighthouse with two hopper circuits, and they behave unpredictably, skipping hoppers and sometimes going slower. Here are the pictures:
The setup: http://prntscr.com/163zzb
In action: http://prntscr.com/16406o
Two minutes later: http://prntscr.com/1640de
Please Mojang fix this bug.

Comment by Tails [ 03/Feb/13 ]

Duplicate of MC-8457.

Comment by GrygrFlzr [ 01/Feb/13 ]

Can finally replicate on 13w05a. Added to Affected Versions.

Comment by Kimitsu Desu [ 31/Jan/13 ]

On the other hand, a hopper and all his adjanced blocks count up to 7, so I can see what Mojang tried to do here, but, since it actually doesn't work, maybe it is a bug after all.
My formula for initial timer setting would be (x + y*2 + z*3) mod 7
What's their's?

Comment by Kimitsu Desu [ 31/Jan/13 ]

The underlying problem is per hoppers design, they have an internal timer that counts to 7 ticks and then moves the items. This timer's initial value is set based on hopper coordinates. If two adjanced hoppers happen to have this timer go off simultaniously, the order in which they are processed depends solely on their order in some hash. That means hopper A might put items in hopper B, and hopper B will put items in hopper C, all in 1 tick. The problem manifests itself, usually, after chunk reloading, because placing hoppers by hand adds more randomness to the timer counter. I'm not sure if redstone signal will reset these timers, I personally think it will not, but it's a possibility too.
The workaround here would be to use comparator output from a hopper, invert it, and lock the same hopper with it, to make sure that hoppers go off one at a time.

Comment by Mason Hughes [ 29/Jan/13 ]

I had a similar issue with a hopper feeding into a dropper that was being powered on and off via a pulsar and underneath that dropper was another hopper. Items skipped the dropper.

Comment by Dennis Müller [ 29/Jan/13 ]

Here are three screenshots of the exact setup I use.
The clocks serve as randomizers and feed into AND Gates to create a slot machine.
The error occurs in all 3 clocks after a few minutes of usage, both in single-player and LAN-mode.

Comment by GrygrFlzr [ 29/Jan/13 ]

Cannot replicate after toggling lever several times.
Please provide additional information, so we can better help with your problem. Was this a single player or multi-player/LAN game?

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