Upon loading a world, redstone components update. The redstone may change based on an unloaded chunk, causeing it to turn off when it should be being powered by something in the unloaded chunk next to it. To reproduce: make a long line of Redstone with repeaters, power
one end, then stand at the other end and lower your render distance. Then reload the world. The redstone will turn off, then turn back on as you load the component powering it. This affects all redstone components that I am aware of, including pistons. It tends to break contraptions as one half may update while the other is unloaded, often sending redstone contraptions into a clock.
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No, it just has to not give them a block update. Then they won't change because they don't check if they are being powered, and there is even less lag upon loading a world. This bug does not occur in PC edition.
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Maybe a Duplicate of MCPE-13714
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Ah, I see. The root cause of the problem is that the powered state of redstone components (like repeaters and comparators) is not saved when they are unloaded, i.e. they completely forget the fact that they were powered before getting unloaded. When they are loaded again, all the components in that chunk receive redstone updates to recover their previous state... with a fatal delay that completely messes up any non-trivial redstone circuitries. So yes, this is indeed a partial duplicate of MCPE-13714 which is a general case of MCPE-13270 and MCPE-13413.
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Confirmed for 0.15 b1
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Can confirm it affects pistons in 0.15.1 beta 1. The flying machine in MCPE-15475 and MCPE-15476 goes one block forward when reloaded.
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Please respond and add the current version if you can reproduce this issue.
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Confirmed in 0.15.4, please reopen.
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The main issue (things breaking because they are partly unloaded while one part updates) would probably be fixed if MCPE-15779 (redstone not loading chunks) was fixed, but this "feature" doesn't really help anything and should be removed anyways.
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Confirmed for 0.15.6
SuperGeniusZeb
Isn't this a duplicate of (or at least related to) MCPE-13608?
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Yes
SuperGeniusZeb
Affects 0.15.90.8 (0.16.0 beta build 5). Again, shouldn't this issue be closed since it is a duplicate of MCPE-13608?
This is very likely to be an intended behavior, because in order to "fix" this, the game must load each and every chunk of the world upon reloading, and continue processing all those redstone components no matter how far you are away from them. I don't think this is feasible.