[kovarex] [0.16.7] Multiple splitters can uncompress belts

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[kovarex] [0.16.7] Multiple splitters can uncompress belts

Post by jonatkins » Sun Dec 24, 2017 10:14 pm

Multiple splitters can uncompress belts.

When everything is flowing at maximum output speed, small gaps form in the output belts, and brief pauses occur on the input belts.

I couldn't reproduce it with a simple pair of belts and a single splitter, so needs to be more complex. Might be splitters directly feeding splitters?
factorio-16-splitter1.png
factorio-16-splitter1.png (981.29 KiB) Viewed 8104 times
factorio-16-splitter2.png
factorio-16-splitter2.png (905.15 KiB) Viewed 8104 times
factorio-16-splitter3.png
factorio-16-splitter3.png (270.51 KiB) Viewed 8104 times

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by Linnun » Mon Dec 25, 2017 5:59 pm

Can you reproduce this using only two rows of splitters? (Having only one splitter-to-splitter feed per lane)

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by PacifyerGrey » Mon Dec 25, 2017 9:29 pm

These belt issues are progressively depressing.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by JulianSkies » Tue Dec 26, 2017 3:09 am

Are you certain that this kind of mess of splitters is actually a balancer and doesn't have some weird issue wherein the output is slower than the input becuse certain portions of the input don't have sufficient output?

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by PacifyerGrey » Tue Dec 26, 2017 7:31 am

JulianSkies wrote:Are you certain that this kind of mess of splitters is actually a balancer and doesn't have some weird issue wherein the output is slower than the input becuse certain portions of the input don't have sufficient output?
Why should it be a balancer? It should not. This is not any useful contraption however splitters should not alter fully compressed flow in any way

This seams to be related to random decompression issues mentioned by AntiElitz
On the last picture I do see a gap on the rightmost belt right after first splitter. If there were no gaps on input this is really bad.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by hitzu » Tue Dec 26, 2017 12:45 pm

It's a limited throughput "balancer" and therefore it can produce gaps by design. For the sake of clear testing try to test it with just one row of splitters, and make another test with additional splitters on the sides instead of solo tile belts.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by Zavian » Tue Dec 26, 2017 1:06 pm

Hitzu why should that design limit throughput when it's being fed 6 full belts?

I do understand that it won't balance the belts if one of the belts is empty, but even then, provided none of the output lanes are backed up, it's output items per second should be exactly equal to it's input items per second. Yes in a balancer you do want to handle an output lane/belt being backed up, and this design doesn't do that, but that doesn't explain the stutters visible in the picture.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by Koub » Tue Dec 26, 2017 1:15 pm

I'm pretty sure all these, as pointed out by PacifyerGrey, are side effect issues of the hardcore belt optimizations the devs added in 0.16 to allow players to make always bigger factories without having to buy a supercalculator. Once the game-braking bugs will have been fixed, they will have some time to find-out how to solve these random belt compression losses, without having to sacrifice too much the performance optimizations. Until then, fly safe please be patient
Koub - Please consider English is not my native language.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by attila » Wed Dec 27, 2017 8:42 am

Linnun wrote:Can you reproduce this using only two rows of splitters? (Having only one splitter-to-splitter feed per lane)
This is the simplest setup I could reproduce the bug:
f_gaps2.png
f_gaps2.png (340.38 KiB) Viewed 7913 times
More gaps with more splitters:
f_gaps.png
f_gaps.png (524 KiB) Viewed 7913 times
More visible when it is moving...

Note: sometimes the gaps disappear after a while, sometimes not.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by golfmiketango » Wed Dec 27, 2017 9:44 am

Koub wrote:I'm pretty sure all these, as pointed out by PacifyerGrey, are side effect issues of the hardcore belt optimizations the devs added in 0.16 to allow players to make always bigger factories without having to buy a supercalculator. Once the game-braking bugs will have been fixed, they will have some time to find-out how to solve these random belt compression losses, without having to sacrifice too much the performance optimizations. Until then, fly safe please be patient
Probably this is true, however, it is notable that, from an end-user's vantage point, precisely the same type of bugs are observable in 0.15. From our perspective, the existing problem simply got worse in 0.16. In 0.15 this got tabled until 0.16. Now in 0.16, we find ourselves in effectively the same situation seeing as it has been announced that belted logistics require some retooling and have some pretty wacky bugs pertaining to compression and side-loading etc. Oh, well, life is hard. Perhaps we shouldn't have gotten ourselves crash-landed on an alien planet given that the laws of physics had yet to coalesce :) I guess there really is "no spoon" (oh, wait, sorry, I just dropped it under the table).

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by golfmiketango » Wed Dec 27, 2017 10:00 am

attila wrote:
Linnun wrote:Can you reproduce this using only two rows of splitters? (Having only one splitter-to-splitter feed per lane)
This is the simplest setup I could reproduce the bug:
f_gaps2.png
More gaps with more splitters:
f_gaps.png
More visible when it is moving...

Note: sometimes the gaps disappear after a while, sometimes not.
If you have enough steel plate or plastic around to test with those, it's a bit more visually apparent. Or sum up "read-hold" of nine contiguous segments of belt and compare to 64 works pretty good (this can give false positives for a tick or two but never three contiguous ticks). quyxkh has an ongoing effort to find an elegant combinatoric compression loss detector that uses less belt entities; looks like it's proving to be a fun challenge.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by CmdrKeen » Wed Dec 27, 2017 9:52 pm

1-2-belt.jpg
1-2-belt.jpg (162.92 KiB) Viewed 7849 times
EDIT: workaround: increase splitter speed (tested at *1.1), but causes another bug

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by golfmiketango » Wed Dec 27, 2017 11:10 pm

CmdrKeen wrote:
1-2-belt.jpg
EDIT: workaround: increase splitter speed (tested at *1.1), but causes another bug
Wait, you mean there is some way in lua to change the speed of the vanilla splitters? I guess that's not really surprising now that I think about it... how's that done?

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by Jackalope_Gaming » Thu Dec 28, 2017 5:51 pm

golfmiketango wrote:
CmdrKeen wrote:
1-2-belt.jpg
EDIT: workaround: increase splitter speed (tested at *1.1), but causes another bug
Wait, you mean there is some way in lua to change the speed of the vanilla splitters? I guess that's not really surprising now that I think about it... how's that done?
Belts have their own speeds in the game files. For the regular yellow belt the file to look at is Factorio/data/base/prototypes/entity/demo-entities.lua. For the rest of the belts the file to look at is Factorio/data/base/prototypes/entity/entities.lua. Regular yellow belts, undergrounds, and splitters are speed = 0.03125, red belts are speed = 0.0625, and blues are speed = 0.09375.

These don't line up with the 13.33, 26.66, or 40 numbers we usually think of though, but it's pretty clear blues are 3 times as fast as yellow and reds are 2 times as fast as yellow.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by kovarex » Thu Dec 28, 2017 6:04 pm

Jackalope wrote:
golfmiketango wrote:
CmdrKeen wrote:
1-2-belt.jpg
EDIT: workaround: increase splitter speed (tested at *1.1), but causes another bug
Wait, you mean there is some way in lua to change the speed of the vanilla splitters? I guess that's not really surprising now that I think about it... how's that done?
Belts have their own speeds in the game files. For the regular yellow belt the file to look at is Factorio/data/base/prototypes/entity/demo-entities.lua. For the rest of the belts the file to look at is Factorio/data/base/prototypes/entity/entities.lua. Regular yellow belts, undergrounds, and splitters are speed = 0.03125, red belts are speed = 0.0625, and blues are speed = 0.09375.

These don't line up with the 13.33, 26.66, or 40 numbers we usually think of though, but it's pretty clear blues are 3 times as fast as yellow and reds are 2 times as fast as yellow.
The speed in the lua file is meters (tiles) per second.
The reason while the numbers are multiplies of 0.03125 is because it is exactly 1 pixel per frame on normal resolution, so the movement looks fluid.

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by CmdrKeen » Fri Dec 29, 2017 7:52 pm

CmdrKeen wrote:EDIT: workaround: increase splitter speed (tested at *1.1), but causes another bug
It's not a workaround, actually. :/

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by kovarex » Thu Jan 04, 2018 6:09 pm

attila wrote:
Linnun wrote:Can you reproduce this using only two rows of splitters? (Having only one splitter-to-splitter feed per lane)
This is the simplest setup I could reproduce the bug:
f_gaps2.png
More gaps with more splitters:
f_gaps.png
More visible when it is moving...

Note: sometimes the gaps disappear after a while, sometimes not.
I'm trying to reproduce it, but without success, could you provide a save file please?

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Re: [kovarex] [0.16.7] Multiple splitters can uncompress belts

Post by CmdrKeen » Fri Jan 05, 2018 5:38 pm

Full reproduction steps using the saves below:
The save was made in .15 to test existing belt behavior on the bug. As expected, the belt will work as expected. (even under long times at game.speed = 100). Edit: when imported to .16, the belts display the same behavior as .15

- when the input flow is interrupted (such as pressing f to pick up items off the belt) it will trigger the behavior happening within moments of releasing the f key. The behavior will oscillate on and off every few seconds.
Attachments
bug-55645-15-instate.zip
in the bugged state
(1.49 MiB) Downloaded 20 times
bug-55645-15.zip
pre-bugged state
(1.41 MiB) Downloaded 25 times

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Re: [0.16.7] Multiple splitters can uncompress belts

Post by attila » Fri Jan 05, 2018 8:50 pm

kovarex wrote:
attila wrote:
Linnun wrote:Can you reproduce this using only two rows of splitters? (Having only one splitter-to-splitter feed per lane)
This is the simplest setup I could reproduce the bug:
The attachment f_gaps2.png is no longer available
More gaps with more splitters:
The attachment f_gaps.png is no longer available
More visible when it is moving...

Note: sometimes the gaps disappear after a while, sometimes not.
I'm trying to reproduce it, but without success, could you provide a save file please?
I've created the save with 0.16.15

The gaps are hard to notice on some zoom levels, try to zoom in/out
splitter_compression_bug.zip
(1.89 MiB) Downloaded 31 times

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Re: [kovarex] [0.16.7] Multiple splitters can uncompress belts

Post by kovarex » Wed Jan 10, 2018 12:22 am

Thanks for the save, it helped me to figure out what was causing it, this one was quite hard, but the more happy I was when I solved it :)
I used variant of it for the automated test that checks that splitters won't uncompress belts this way again.

TL;DR
Fixed for the next release.

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