I can confirm low spawn rates, especially for mob traps built at high altitudes. For me, it's very easy to reproduce in any world. Simply pillar up and build a little platform, and wait 24 tiles away. Mobs spawn eventually, but really slowly, not nearly as much as in earlier versions.
I've tried:
Changing the render distance from 8 to 10 and even 16. (Which my PC can't really handle.)
Allocating more memory to Minecraft.
Running Minecraft from a fresh game directory.
Checking difficulty and doMobSpawning setting.
Running my map through the multiplayer Minecraft server, and joining on localhost.
Nothing seems to help, except downgrading to 1.7.2. When running 1.7.2, the same map will spawn hostile mobs with high speed right away!
It's an odd bug, because I follow Youtubers that play on 1.8.0 and the 1.8.1 pre-releases, without any issues with their mob traps. The only difference I could think of is that I have a lower-end PC, and perhaps less chunks are truly loaded, and therefore less mobs can spawn? Any difference made to spawn rules since 1.7.2 could be the culprit though.
Are there any other settings I could apply to crank up mob spawning in the meantime? I seem to remember a server setting for this, but maybe I'm thinking of Bukkit...
@Ioan Vira: I repeated the test, and used MCEdit to create a copy of my spawn platform in the same X/Z location, but at Y level 5. I filled the 300x300 block area around the platform with air, to prevent mobs spawning elsewhere. Spawn at Y level 5 is normal! When I return to my original platform (at Y level 238), spawn remains very, very slow.
Something to note: my view distance was set at 8 chunks for this test. I already established that changing the view distance has no effect at my original platform. The client used for this test was 1.8.1-pre4.
@Ioan Vira: If I construct both platforms in MCEdit (one on Y 5, and one on Y 238), the lower spawns normally and the higher spawns slowly. This suggests it's not an MCEdit issue.
@Ioan Vira: You are right! Spawn is low at Y 33 as well.
edit:
For ease, I made my platform a square of upside down stone slabs. Fresh out of MCEdit, nothing spawns on top. If I however use a /fill command in-game to turn it into cobblestone, then back into slabs, spawn is fixed.
Commands I used to refill the platform:
/fill ~-32 ~-1 ~-32 ~32 ~-1 ~32 minecraft:cobblestone
/fill ~-32 ~-1 ~-32 ~32 ~-1 ~32 minecraft:stone_slab 11
Perhaps my issue is MCEdit related after all? Still, an MCEdited platform on Y 5 is fine, and Y 238 is fine when using 1.7.2, but broken in 1.8.1-pre4.
@JamestheDouglas I put spawners down in my world, before re-doing the MCEdit builds with commands and turning up the render distance whenever I want high spawn rates (which works!). Lots of workarounds to try.
I can confirm low spawn rates, especially for mob traps built at high altitudes. For me, it's very easy to reproduce in any world. Simply pillar up and build a little platform, and wait 24 tiles away. Mobs spawn eventually, but really slowly, not nearly as much as in earlier versions.
I've tried:
Nothing seems to help, except downgrading to 1.7.2. When running 1.7.2, the same map will spawn hostile mobs with high speed right away!
It's an odd bug, because I follow Youtubers that play on 1.8.0 and the 1.8.1 pre-releases, without any issues with their mob traps. The only difference I could think of is that I have a lower-end PC, and perhaps less chunks are truly loaded, and therefore less mobs can spawn? Any difference made to spawn rules since 1.7.2 could be the culprit though.
Are there any other settings I could apply to crank up mob spawning in the meantime? I seem to remember a server setting for this, but maybe I'm thinking of Bukkit...
@Ioan Vira: I repeated the test, and used MCEdit to create a copy of my spawn platform in the same X/Z location, but at Y level 5. I filled the 300x300 block area around the platform with air, to prevent mobs spawning elsewhere. Spawn at Y level 5 is normal! When I return to my original platform (at Y level 238), spawn remains very, very slow.
Something to note: my view distance was set at 8 chunks for this test. I already established that changing the view distance has no effect at my original platform. The client used for this test was 1.8.1-pre4.
@Code Raider: I repeated the test with view distance 10, same results. At Y 5 my platform spawns normally, at Y 238 it spawns very slowly.
@Ioan Vira: Blocks place just fine on the higher platform. In fact, if I place a mob spawner for zombie pigmen, it spawns just fine.
@Ioan Vira: If I construct both platforms in MCEdit (one on Y 5, and one on Y 238), the lower spawns normally and the higher spawns slowly. This suggests it's not an MCEdit issue.
@Ioan Vira: You are right! Spawn is low at Y 33 as well.
edit:
For ease, I made my platform a square of upside down stone slabs. Fresh out of MCEdit, nothing spawns on top. If I however use a /fill command in-game to turn it into cobblestone, then back into slabs, spawn is fixed.
Commands I used to refill the platform:
/fill ~-32 ~-1 ~-32 ~32 ~-1 ~32 minecraft:cobblestone
/fill ~-32 ~-1 ~-32 ~32 ~-1 ~32 minecraft:stone_slab 11
Perhaps my issue is MCEdit related after all? Still, an MCEdited platform on Y 5 is fine, and Y 238 is fine when using 1.7.2, but broken in 1.8.1-pre4.
@JamestheDouglas I put spawners down in my world, before re-doing the MCEdit builds with commands and turning up the render distance whenever I want high spawn rates (which works!). Lots of workarounds to try.