Bukkit

Pastebin link to your Config (I will ignore your ticket if it doesn't contain this:
http://pastebin.com/Aadu1DYV

What steps will reproduce the problem?
1. Place a mobspawner.
2. Let the mobs (spiders) follow/attack you.
3. Mobs dissapears randomly.

What is the expected output? What do you see instead?
No mob dissapearing while there are people close to the mobspawner.

What version of the product are you using?
2.9.0 of ClearLagg and the latest version of Spigot.

Do you have an error log of what happened?
No.

Please provide any additional information below.

When I have this option on true: "remove-mobs-on-chunk-unload" the in my case, spiders are dissapearing while we are standing with 2 near the mobspawner.

If I turn that option to false, the mobs don't dissapear when we are near the mobspawner.

If the mob-spawner chunk is unloaded, the mobs that came from the mob-spawner will be removed.

Is that possibly your problem?

@bob7l: Go

That's how it should be. But we are just standing/walking and attacking the spiders when they randomly dissapear. Chunks don't unload when people are in, do they?

@Sikatsuu: Go

Then it's possible an invalid ChunkUnloadEvent is being fired. That could be caused by spigot, or a plugin.

@bob7l: Go

I can't imagine any of my plugins are using that event. So it does work for you? Are you using spigot or bukkit?

@Sikatsuu: Go

Yeah it works fine for my test servers. It's also possible the chunk-hash key isn't unique enough, in that case i need to implement an extra check.

I'll release another dev build in about 5 hours when i'm free with this fix applied.

@bob7l: Go

I didn't notice this on 1.8 and I didn't change any plugins except for updating. Will test that devbuild, thanks!

Yep, I have same issue. When updated from 1.8 to 1.9 then this happened to me. Seems spigot causes it :/