abfielder

In reply to Bobert - The issue raised by Turbo Donkey seemed to specifically occur following the upgrade to 21.40 , nothing in the world seems excessive and the issue seems to have been introduced in 21.40+ rather than being a general I have "lag issue".

So we've just updated our server to 1.21  (from 1.20.2) and started getting lag spikes, once I figured out it was every 5 minutes I ran a spark trace to figure out it was the save that was causing issues. I've replicated the issue in vanilla and used the perf command to generate the logs - 2024-06-26_08_59_36-LTSWorld-1_21.zip

Something's taking too long! 'root.nextTickWait./save-all.execute save-all' took aprox 835.76711 ms
Something's taking too long! 'root.nextTickWait./save-all' took aprox 836.669464 ms
Something's taking too long! 'root.nextTickWait' took aprox 851.313009 ms
Something's taking too long! 'root' took aprox 857.481981 ms
 
I can share the world also but a) it's over 8gb zipped up, it's a long term save I don't want other's being able to download so I would need to find a way to share privately with the mojang team.

For now I've turned off auto save by doing /save-off and I've created a routine on the server to do a /save-all once every 15 minutes, we still get the lag spike but at least it's less regular.

Still happening in 1.20 and more noticeable especially as the new armour trims are encouraging people to go looking for shipwrecks.

Yep, same is happening too me. 

Ahh it's not the TP command that's the problem, I've just flown to the same location which is 2500, 3000 blocks out and it stops loading the new chunks as well.

The layouts are identical, the difference appear to be simply down to the fact the lower one has some of the new blocks and has part of it in the new dripstone cave and it's shifted by a few blocks.

I think the screenshots below arethe best way to demonstrate it. Both taken looking in exactly the same direction. I've put the commands below the pictures so you can see it easier. Both have have 4 tunnels facing towards you,

The bottom left tunnel on both has the cave spider spawner. The bottom right tunnels both have the "steps" coming down towards you, although the lower one has tuft.

The top two tunnels if you look at the block patterns on the ceiling (the blocks that stick out) they are identical. The third command should show you what I mean, the only difference is that 4 of the blocks in the pattern on the top tunnel are dirt.

/execute in minecraft:overworld run tp @s 215.16 34.07 397.59 -178.06 0.15

/execute in minecraft:overworld run tp @s 215.16 -35.30 397.59 -178.06 0.15

/execute in minecraft:overworld run tp @s 210.61 -39.78 357.07 -181.81 -90.00 (shows the block pattern in the left tunnels ceilings)

/execute in minecraft:overworld run tp @s 226.91 -40.15 369.30 -181.66 -90.00 (shows the block pattern in the right tunnels ceilings)

This seems to be the same issue I've reported #MC-228134 I will need to revert our server to vanilla to get the screenshots and videos of the issue occuring (we use fabric but the issue occurs on vanilla).

Besides screenshots and/or videos is there any other logging that would be useful? I'm comfortable using tools such as netmon/fiddler etc... if it would be useful.

We are getting this issue loads in our world in the nether. Invisible blocks all over the place, have to place another block and mine it. I sometimes end up getting coal or Redstone from these blocks. It also sometimes turns out to be an invisible pigmen that is then angered.

That's normal, you have to smelt them in the furnace.