Low mob spawn rates on low render distances

Calling this a duplicated issue is wrong as the pictures show that I was in Hard Mode and not Peaceful Mode. I wouldn't exactly consider this issue resolved even though I have improved mobs spawns. As I said before I've only gotten about 15-20 hostile mobs, but that is within a small radius of my character. Again, I want to point out this line in the Dev Console output that I provided: "22:40:07 INFO: Client> 22:40:07 Server thread/WARN: Can't keep up! Did the system time change, or is the server overloaded? Running 2102ms behind, skipping 42 tick(s)." An answer as to what exactly that is would be very helpful in understanding what exactly is going on as it seems extremely relevant.

Your system cannot keep up so the server skips ticks to keep up with realtime. Either another process is slowing down your server or your server simply doesn't have a powerful enough CPU.

This has no effect on mob spawning.

A server I'm playing on is experiencing the same issue: Hostile mobs spawning extremely rarely, server logs have "Can't keep up" message. The world was created in 1.7.2, and experienced no issues until the minute the 1.7.4 update was applied to the server. The server in question has at least 2GB RAM, and no users have render distance set greater than 8.

I agree with Matthew that this issue should be marked as unresolved, not duplicated.

I still have this issue too. Mobs spawn fine in 1.7.2 but not in 1.7.4. When I reinstall everything, they spawn again at first in 1.7.4, but no longer after moving to other chunks.

Reopened.

I seen the issue too in creative mode. If I exit to title and enter again, mobs spawn.

i too have this issue , anything i can do to help i will

I read once it had to do with the chuncks. Like lowering your it to 8. But on servers, I can confirm.

I have this issue too. In minecraft 1.7.4 mobs stopped from spawning after a few nights in my survival world but in 1.7.2 mobs spawn normally. I have to restart the game in order to mobs spawn again in 1.7.4

Please do not use caps. I removed your previous comments because of unnessecary insults on your part.
Remember: We're just moderating this tracker, and in order to do this, we also need to be strict on some parts. I, for my part, cannot reproduce this either. We'll pass this on to the developers, but as Dinnerbone is on Winter vacation and the rest of the team soon as well, don't expect any answers soon.

Maybe MC-42174 is the cause ?

I will have to check the Chicken Jockey theory, but from what I saw that wasn't the issue. One thing's for sure is that the spawn rates are very finicky and inconsistent. I'll have to look into this for sure though.

I had no ideea about MC-42174. However I can say that my case (which occured in creative mode) had no portals to nether yet. I just created the world, found a witch hut and created two platforms and I was observing the spawn rates. I was ofcourse disapointed until I realised that also other mobs are missing in the area. Exit to menu and loading the map again during night made all mobs spawn again.

I think this is a duplicate of MC-2536. With render distance below 8-10 (I can't remember exactly) spawning is like its been disabled. It's clear by the screenshots that the selected render distance is lower than that.

Do you guys have low resource pc's? I'm having this issue on my laptop in my main world, but not on superflat (which needs less resources).

Maybe and error in the code of 1.7.4 leads to a high resource requirement to spawn hostile mobs. (maybe that's why some can't recreate the issue since they have high spec machines). Just a theory

edit Mob respawning seems to return to normal for a little while after exiting and re-entering the world. But only in the area I was in. Very weird.

That actually makes a lot of sense. I am on a laptop and usually only run into one or two hostile mobs every night, but I watch people on YouTube with powerful computers and nothing seems to be going wrong for them. However, I tend to keep my render distance very low. I need to test this out.

I made some tests in creative mode and I noticed the following:
The world was a custom flat desert, no decoration, no villages, nu structures.
Rendering distance does not influence the spawn. I used both 2 and 16.
The mobs do not spawn until I place some block. I used cobble stones and torches.
The spawn area is larger around the first spawn location.
In new places (I mean further from the spawn point), if I place only one block, the area where mobs can spawn is quite low.
Usually the area is low enough to prevent the spawning of mobs until the player goes further away from this point.
If I create taller pillars (4-5 blocks) the area seems to increase. I am not sure if placing torches on the top of the pillar has an influence or not.
Flying between these pillars shows that the mobs spawn only around these places.
If I remove the previously placed blocks the spawn area remain when I walk between these locations.
I made these tests in 1.7.2 and 1.7.4 mostly without internet connection because I have a new firewall which gives me a couple of pop-ups when the game starts.
I was setting night using /time set 15000
I seen no strange messages in the development console trace.

I do not have similar problems in usual survival maps. Just in creative mode. However it is interesting that the game does not rely only on the block type to decide to spawn mobs but also on some kind of player activity on the map. And later if this activity is removed (placing and removing a block) the game still remember this information. For people who experience problems in survival mode, possibly this information (valid spawn areas) might be cleared (or not checked) and initialized correctly again when map is loaded.

One more note: in creative I tried first with a normal plain biome, with grass and 2 villages nearby. Lots of slimes spawned during day everywhere. The mob spawning seemed also ok at night time.
Therefore I disabled buildings, caves, dungeons and I noticed the problem as described above in ice plains first and then in desert.

I do not want to test anymore but if somebody can try to reproduce this (successfully or not) would be cool 🙂

More tests with Creative mode, Generate Structures: OFF.
Seed - y=...
2;7,1,19x12;2; - y=21 ok
2;7,1,25x12;2; - y=27 ok
2;7,1,27x12;2; - y=29 ok
2;7,1,28x12;2; - y=30 ok
2;7,1,29x12;2; - y=31 not ok, make a 2 block pillar and mobs spawn around it
2;7,1,30x12;2; - y=32 not ok, place 1 block and mobs spawn around it
2;7,1,31x12;2; - y=33 ok
2;7,1,32x12;2; - y=34 ok

2;7,1,38x12;2; - y=40 ok

2;7,1,46x12;2; - y=48 not ok, place 1 block and mobs spawn around it

2;7,1,60x12;2; - y=62 ok
2;7,1,61x12;2; - y=63 not ok, make a 2 block pillar and mobs spawn around it
2;7,1,62x12;2; - y=64 not ok, place 1 block and mobs spawn around it
2;7,1,63x12;2; - y=65 ok
2;7,1,64x12;2; - y=66 ok

Machiel van Dorst could be that! that describes my situation. The mobs spawn againg for a little while after re-entering to the world.

Michiel van Dorst, I'ves got the same problem, so what could be the solution? Do you think that If i dedicate it more memory ram it could fix, or is not that?

I'm no developer so I'm not sure. Since it worked fine in 1.7.2 and earlier, I'd think there is a solution for this.

I have already tried that and doesn't work :'(

Sure they want to fix it. The holidays are barely over, just give them some time.

But the probem is not my map right?, I mean if they fix it, I will can use my map, and it will be fixed too or I will have to change my map? Idk if I should to work on it now..., by the way, Happy New Year! 🙂

@Victor
If the mobs spawn correctly for a while after you exit and reload the map, then the problem occurs at runtime.
In this case we can assume the fix will not force us to change the maps.

Thank you so much for your help 🙂

I've encountered the bug too after upgrading to 1.7.4, only in my case mobs have ceased to spawn completely. Mob spawner blocks are still functioning properly, but that's it. Restarting the server doesn't help, neither does switching to Peaceful and back. Log doesn't show any errors, aside from rare "Can't keep up" warning.
If I start new local world in 1.7.4 client, then I get small amount of monsters, but I can't get monsters to spawn on my server at all.

Server info:
$ java -version
java version "1.7.0_25"
OpenJDK Runtime Environment (IcedTea 2.3.10) (7u25-2.3.10-1ubuntu0.12.04.2)
OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)
$ uname -a
Linux VindicarServer 3.2.0-57-generic #87-Ubuntu SMP Tue Nov 12 21:35:10 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Did some more testing: found that if I run a multiplayer server and connect to it via localhost, the spawning is perfectly fine. It seems to me that the issue lies with the implementation of the server in single player (which is basically a local multiplayer right mods?)

I've tested on 4-8 chunks loading, since that's all my laptop can handle. Single player: issue is present, multiplayer: spawn rates are normal.

Hope this helps solving it.

Machiel van Dorst Is true! , i just test it !

I have this problem too, please help!. What Machiel van Dorst said is true.

So to summarize what we have found:

Spawn rates seem lowered significantly for mostly low/mid end machines. This may be why some of the mods/mojang have trouble reproducing the problem.
The issue wasn't present in 1.7.2, so our low/mid end machines can handle normal spawning just fine.
It's mostly not affected by how many chunks are set to load within video settings.
Can't keep up messages are related to the CPU, which sometimes can't keep up with game ticks. This has no effect on spawning, just freezes the game for a bit.
Seems to be only present in singleplayer from personal experience, if I run a server spawning is fine.

One more personal thought: maybe it's related to the 8 chunks + render fix implemented between 1.7.2 and 1.7.4?
edit: I said it wasn't affected by chunk loading but that doesn't seem entirely true. When I set it to 12, which my laptop can't handle at all, the FPS is obviously very low but mob spawning returns to normal! Hope this helps with a solution.

I agree, and am having exactly the same problems as all of the other commenters. I'll just switch back to 1.7.2 for now, because in that version, the mob spawning works just fine. The entity count in F3 goes from 16 Max to 80 between 1.7.4 and 1.7.2. Definitely a serious problem that should be fixed.

Experiencing this as well. Running a server, hardcore mode, difficulty 3. Polled the players and they've seen a total of 2 mobs in 4 game days. Somethings not right there...

Just FYI I suspect this goes back to at least 1.6.2 when zombie spawning was changed, as we had the same problem on our server, it's possible it's just more noticeable now. 1.7.x we started a new map and no issues since.

@Chris Comments such as that will be muted as you are not providing any information to further the resolution of this bug, only complaining.

We are volunteer moderators not developers, we cannot fix your problems. The comment above was to notify people that this issue may extend farther back than expected, allowing the devs to check other versions to determine where the issue came from.

@Talven81 I agree with you.

p.s. You must be a moderator. 🙂
http://www.design.caltech.edu/erik/Misc/balloon.html

Issue is still present for me in 14w02a and 14w02b in its current form.

Im running a 1.7.4 server and I personally noticed that there were very few mobs, not none, but just very few. Then a couple of people on the server talk about how little mobs there are spawning. So this is definitly an issue. Running survival on easy, vanilla 1.7.4 server, map ~2 weeks old.

After downloading 14w02c, I can confirm that this is still an issue for me. Anecdotally, I've noticed that I seem to get normal spawn rates when I am within my spawn chunks.

Also confirming for 14w02c.
I can safely walk around in survival at night on hard difficulty. Mob spawning should be high, but there are hardly any hostile mobs.

I have the same problem exactly. I opened a topic on the minecraft forum months ago, if someone wants to.comment.
I hope they can fix the problem in official release.

I have this issue in 1.7.4 on my multiplayer server running on Normal difficulty.
We can stay out all night and see only a few mobs (or none at all some nights).
If I download the world and play it on my local machine, I see mobs spawning almost instantly during night time (as expected).

This is a new world, created in 1.7.4.

(low mob rates is making it very hard to gather certain resources (slime balls, enderpearls etc)

Does your system have high specs? Like do you get 60+ FPS with high render distance and Fancy Graphics.

It's an i7 with 8Gig RAM and a Intel HD graphics card.
Playing single player, 60FPS is the highest I get - usually around 30-40 during play.
Yes, I play with Fancy graphics and smooth lighting.

I just get a new PC minecraft gets 100-80 FPS in fast graphics and 60-40 with fancy graphics

processor AMD A45300
Integrated Raedon HD 7480D
4 GB Ram

I still Have this issue, only few mobs spawn using 10 chunks of render distance.

i tested in ubuntu 12.04, ubuntu 13.10 and windows 7 latest java version

Can you try it with 12 (even if that lags). I recently found that when chunks are set to twelve, spawning does improve for me (even though my system can't handle it). So maybe it's related to rendered chunks after all.

Render distance: 16 chunks
Difficulty: Hard

At first the mob spawn improves, but if i go too far from where i spawn (spawn chunk, bed or where i exit and save the game) the mobs not spawn anymore. I only get 1 creeper. This happens only in 1.7.4

I attach the screenshot : 2014-01-18_13.46.48.png

EDIT: This happen in the 1.8 snapshots too ...
EDIT: squids and nether mobs also not spawn. Not seems to affect pigs, ocelots, sheeps, wolfs, horses, cows and chickens.
EDIT: Using gamerule doMobSpawning true and changing difficulties does not make mob spawn again. The mobs only spawn again by re-entering in the world .

Sorry for my bad english i'm from Mexico

Does anyone know if this is still an issue in the latest snapshot?

Yes it is still an issue. Did some more testing, and one of the crucial things about this bug is: the chunks were you start when loading your world seem to spawn mobs, the rest don't. Exiting and re-entering resets where mobs spawn it seems like.

Mods: let me know if I can test some more specific scenarios.

Some times enter in the nether an coming back to the overworld makes some mobs spawn again. I notice something strange: a zombie spawn and despawn before my eyes, i was close to the zombie, there is something really wrong since 1.7.4 update. Another thing is that the mobs pawners are not affected, i just found one, I really don't understand what is wrong, if there something i can do to help let me know.

Did some more testing: increasing the render distance definitely increases spawn rates back to normal IF the system can handle it. It doesn't work as well in the overworld for example, but it works in the end on a big flat platform away from the main island. My laptop can handle 60 FPS with 12 chunks rendered and enderman spawn like craze, with 8 chunks it's low again.

Now somebody should update the headline:
"It's mostly not affected by how many chunks are set to load within video settings. "
and add
" with 12 chunks rendered and enderman spawn like craze, with 8 chunks it's low again."

It would be nice to know if the developers found the root cause or they had no time to look at all.

I noticed that if I change the render distance, increasing it or decreasing it, the surroundings are being reinitialized like if I just reloaded the map.
Testing this bug must be observed carefully without switching often these settings.

For the Mods, bug is still present in 14w03b snapshot. Also for the summary, turns out that render distance set does affect the bug (8 vs 12 in my case). Let me know if I need to test anything for you.

Did some more testing, found a new surprising result. My laptop can run 8 chunks max without lagging to much. But, when I set render distance to 8 or below, the lower spawn rates occur. When I set it to 9 or higher, my game lags pretty bad but the spawn rates are normal.

Let me know if I need to test some things.

Can confirm what Machiel tested as this is what is happening on my SMP server. Low spawn rates are directly affected by render/view distance. A view distance of 10 on my SMP server and spawn rates are normal but the server lags like crazy/tick is through the roof. If I set it to 9, it's a compromise between lag and spawn rates. If I set it to 8 lag/tick virtually disappears... and so do hostile mobs.

Great, so now we know for sure how to recreate the problem: Set render distance to 8 or less.

I think I have the same issue on my server. I lowered the view distance to 6 by now, but it doesn't seem to affect it at all. In fact, I think mobs might not be despawning at least in certain areas like world spawn or possibly The End.

I disagree. Currently I have server render distance set to 10, and client render distance maxed out.
Still no hostile mobs spawning AT ALL.

That's odd. Difficulty set not non-peaceful and mob spawning on in settings? What are the specs of the server system?

Its an AMD Octacore with 2.4 GHz, 16 GB RAM (4 GB assigned to MC). I use Oracle Java SE 1.7.0_45b18. Also McMyAdmin. And there's about 1.5 TB harddisk space left.

I use the following custom options (beside the 4GB) to start MC:
-Xmn512M -XX\:PermSize\=128m -XX\:MaxPermSize\=256m -XX\:+UseParallelGC -XX\:ParallelGCThreads\=8 -XX\:+CMSParallelRemarkEnabled -XX\:+DisableExplicitGC -XX\:MaxGCPauseMillis\=50 -XX\:SurvivorRatio\=16 -XX\:TargetSurvivorRatio\=90 -XX\:+UseFastAccessorMethods -XX\:+AggressiveOpts -XX\:+UseAdaptiveGCBoundary -XX\:-UseGCOverheadLimit -XX\:+UseBiasedLocking -XX\:MaxTenuringThreshold\=15 -XX\:UseSSE\=4 -Djline.teminal\=jline.UnsupportedTerminal

And yes, of course the difficulty setting is "Hard".

Server specs:
CPU: 4x Intel(R) Atom(TM) CPU D525 @ 1.80GHz
RAM: 4GB

System usage:
Cpu(s): 2.8%us, 0.1%sy, 0.0%ni, 97.0%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 4032564k total, 3694464k used, 338100k free, 132536k buffers
Swap: 4173820k total, 35744k used, 4138076k free, 2130056k cached

Java version "1.7.0_51"
OpenJDK Runtime Environment (IcedTea 2.4.4) (7u51-2.4.4-0ubuntu0.12.04.2)
OpenJDK 64-Bit Server VM (build 24.45-b08, mixed mode)

Game rules:
gamerule doMobSpawning
[Server thread/INFO]: doMobSpawning = on

--------------------- server.properties ---------------------
#Minecraft server properties
#Sat Jan 25 20:27:36 MSK 2014
generator-settings=
op-permission-level=4
allow-nether=true
level-name=world
enable-query=false
allow-flight=false
announce-player-achievements=true
server-port=25565
level-type=DEFAULT
enable-rcon=false
force-gamemode=false
level-seed=4586832350340175357
server-ip=
max-build-height=256
spawn-npcs=true
white-list=true
spawn-animals=true
texture-pack=resource-pack.zip
snooper-enabled=true
hardcore=false
online-mode=true
resource-pack=
pvp=true
difficulty=1
enable-command-block=false
server-name=Vindicar's Server
player-idle-timeout=0
gamemode=0
max-players=8
spawn-monsters=true
generate-structures=true
view-distance=10
spawn-protection=16
motd=Welcome to Vindicar's server
--------------------- server.properties EOF ---------------------

Of the few monsters that I see in 1.7.4, most seem to be spawning under trees or underground. Like the light level, monster spawning correlation is off. I'm trying to play hardcore, but not much point. I am playing around with the settings, but have not seen any significant difference.

Confirmed for 1.7.5 (of course!) :/

Sometime I play old versions. I loved the old terrain generation more, better boat control... and we had no such problems. But sometime I would like to have to have some of the new stuff too.

I experienced this problem in 1.7.4, using 2GB and then 4GB memory allocation. I have been running 1.7.5 without any command line switches and my spawn rates seem to be back to normal; my mob farms are operating at nominal production rates and I am getting mobbed in the Nether again.

So there may be a confluence of factors that result in low mob spawn rates. Initially I noticed that no mobs would ever spawn on the island I spawned on that is in the middle of an ocean. Even after spending several days leveling the island to be flat at sea level, and exploring and lighting some caves below, I never had a single mob spawn on the surface, and saw very few in the caves below. After finding this bug and doing further testing in creative mode, both on fast and slow machines, I can confirm that on the slower machines, there are fewer mob spawns, as indicated by the entity counter in the debug window. This persists even after flying very high to force underground mobs to despawn, and then dropping back down. In addition, even on the fast machine, a mob spawning on the surface of the island is very rare. A dup of this bug I found first thought that the spawns were inhibited by moonlight, so I tried building a roof of wood above the island in creative mode to see if that would make mobs spawn. Instead I got mobs spawning on the roof, rather than the island below. Based on this, it seems that besides the speed of the machine lowering spawns in general, they still have a heavy tendency to spawn in underground caves, and dislike spawning on uneven terrain.

The world seed I noticed this in where it can easily be reproduced in creative mode is -9084881734462559969, and this is all with 14w11b, My fast machine is a sandybridge ~3.2-4 GHz quad core with a radeon gpu, and the slow machine is a celeron with integrated intel graphics. The slow machine averages about 15 fps, and the fast machine averages about 35. The entity counts on the slow machine were typically in the ~30-45 range, peaking at about 75, and on the fast machine, they generally stuck to around 100.

confirmed in my mac, having the same problem in mc 1.7.5

Almost all dynamic events are performed in the tick update, for example:

• mob spawning and despawning
  See: http://optifog.blogspot.de/

If game ticks are skipped, it could lead to this behavior...

They say "The game has achieved sentience." Maybe this bug will fix itself soon.

maybe @unknown has found out in the comment of December 2013 what's better described in MC-55172 "Mobs do not spawn at the heights 16, 32, 48, 64, 80... (Multiples of 16)".
@Anyone still having this issue: Please try to recreate that issue with world heights of multiples of 16

I am running a 1.7.2 server and we're experiencing the exact same issue, so it is very much present in 1.7.2 as well. Monsters were spawning for a couple of hours, then suddenly stopped. I have not seen a monster in days now. Anything I can do to help? Or will Mojang care about 1.7.2 at all? No mods are out for later versions of Minecraft, and 1.8 won't be out for at least another 3 months. Can you guys not just make a small mod that will fix the issue? Like copying the spawn mechanics from 1.6.4? Please? We're getting desperate...

My feeling is that something was changed in the architecture of the software and in the new one happens a kind of deadlock or priority inversion on slow running or overloaded machines. I wonder if in 14w20 is still reproducible because they optimized the software. If somebody can reproduce, and if it does not mind about his world, type the command /kill @e[type=!Player] . This would kill everything. Then wait a few seconds and type the command again and see how many mobs die next time. You can also use /tp @e[type=!Player] x y z to gather all mobs into one place before killing them. This would give an indication if the spawning process resumes (or if it works at all) after the world is "cleaned".

this never hapend for me. but i still thick i can hapen

This happened to me, but it was very strange. I was playing in 1.7.4 for awhile, then eventually no mobs spawned. Strange part is, this happened for about the next ten in game nights, then went back to normal. It was strange, and I think it happened a second time, for a shorter duration.

So you say "It's mostly not affected by how many chunks are set to load within video settings." Does that mean you still have that same problem if your chunk loading distance is set to maximum? If so please only test this if your chunk loading distance is set to maximum, because if your chunk loading distance is too low, mobs will not be able to spawn, because either the chunks that are far enough away for mobs to spawn are not loaded, or mobs spawn in the outermost two chunks, which means they get stuck and you don't get to see any mobs spawn.

That summary is wrong. I wrote that summary a while ago and a mod put it on top. But we know now that mobs spawn normally when chunks are set to 9 or more, and barely when set to 8 or less.

Then this post should be corrected, because as it is now it says that what is causing the bug wouldn't actually be related in any way.
It should describe this bug properly, the actual bug is that a render distance of less than 9 blocks will affect mobspawing as they could only spawn in chunks that are not loaded, or in the two outermost chunks, which means they don't get any updates.
Also this can happen on servers if the chunk loading distance is set below 9 in the server.properties file.
So this means this does not have anything to do with how fast your computer is or anything.

Not the case for me. I play minecraft at 3-4 chunk render distance and see tons of mobs spawning every night and in caves.

I guess you are playing on a server then?

Nope. Single player. I play at 3 chunks most of the time, and they spawn as normal.

Well, only far below you then, right?

With servers, i found that if you set the view distance to 9 or higher, all is well, 8 or lower, low spawn rates. That translates into the 9+ vs 8- chunk setting in single player. The distance set by the client doesn't matter, since the server handles spawns.

Exactly, the issue is that the render distance also reduces the range in which the chunks are loaded around the player. And if the loaded chunk distance is less than 9 mobs cannot spawn properly.

I had this issue on my server (hosted externally) when the allocated RAM was low (512MB).
Increasing it to 1024MB appears to have resolved the issue for me.
Note that view-distance has always been set to 8 in the server.properties config.

Hmm weird. My (externally hosted) server had the issue with 2048 MB Ram and view distance on 7 or 8. Only upping it to 9 fixed it.

This is not related to RAM usage in any way. If you have a view distance of 8 and stand around, you'll soon see no mobs spawning anymore, because most mobs will not be able to despawn.

I only have a small number of players (8 in total, usually 3-4 max at one time), so this might be a factor.

This is not what this issue is about. The problem is that mobs cannot despawn and therefore block the mobcap if your viewdistance on the server in multiplayer or the renderdistance in singleplayer is below 9.

I don't think so, since the issue also occurs in single player. The issue seems to be: render distance (SP) or view distance (MP) set to 8 or less. Which is all some machines can handle, making it an issue.

That is why I said

viewdistance on the server in multiplayer or the renderdistance in singleplayer

The problem is that the renderdistance in singleplayer also sets the distance chunks are loaded in, like the viewdistance on servers does.

This is not what this issue is about. The problem is that mobs cannot despawn
and therefore block the mobcap if your viewdistance on the server in multiplayer
or the renderdistance in singleplayer is below 9.

Wrong. If the map cap were hit, then you would have a normal spawn amount. Just because they are on the other side of a wall so you can't see them does not mean there is anything wrong with the spawn rate. The issue here is that the map cap is never reached because the mobs aren't spawning in the first place. Also mobs will despawn anywhere over 2 chunks away anyhow.

I think you don't quite understand how the loaded chunks work. In the two outermost chunks mobs cannot despawn, because they do not receive any updates. Also if you don't have any chunks loaded that are far enough away for them to spawn they will simply not be able to spawn, which is the issue with that.

Is there to check if the mob cap was reached?
The only thing I figured out was to use /tp @e[type=!Player] x y z to gather all mobs into one place and /kill @e[type=!Player] to kill everything except player.
Make a backup copy of the save and use these commands to exclude or confirm the mob cap scenario.

When I seen this problem, the number of entities shown in the debug screen was small. Since 14w20 I could not anymore reproduce this bug. I also play less often.
And I play only single player.

When I noticed the bug, I also found out that restarting the game restores the spawn rate.
The only causes I could think about were:
1) deadlock or even more probable priority inversion in some threads. In this case changes from one snapshot to another regarding optimizations of mob spawn could impact the occurrence. This case explain also why this happens only for few players. And changing view distance would impact runtime and influence this problem.
2) the mob cap. I guess if you go further in the world, the mobs would start spawning in the new areas. Right? Are any chunks always loaded in single world where these mobs could accumulate? The spawn location chunk is always active?
3) a de-synchronization between the day/night cycle and the spawn algorithm. Having no access to any decompiled code, and because I used commands to chance or freeze the time, I also assumed things may be implemented in a complicated way...

If we eliminate case 2), and assuming case 3) is very unlikely (a modder can give us a sure answer) then only looking into the source code during runtime can we find the problem.

Don't forget MC-55172 "Mobs do not spawn at the heights 16, 32, 48, 64, 80... (Multiples of 16)".

That has a different cause and I avoided to insist on that one. That is reproducible each time and is a simple bug to fix but at the same time does not worth the effort. It was nevertheless interesting that the spawning area remained active/valid even after I removed the blocks. Anyway, people trying to figure out an exact setting which triggers this behavior is not very useful. Minecraft has a huge number of players and still only a few complain... so is not about settings.

The "priority inversion" which I mentioned is for the developers if they read this. If you have the power to make them aware of this hypothesis would be nice. Nobody else can investigate this except those who reverse engineer the code to make the the Forge...

You are right, Kumasasa, that test made me think that some blocks have in RAM an associated attribute which marks them as "valid for spawn".
This I would mark as 4)
It could be that due to optimizations, the game do not search each time where/which blocks are valid but instead it uses a kind of lookup table. So if the user changes some area, that area is updated and inserted or removed from the table based on block type, how much space is above them...
If suddenly the area where mobs are supposed to spawn are eliminated from this check, the game behaves as if everything is covered with half blocks until the world is reloaded.
Again this is something to be investigated internally, looking into debug traces.

Message for mods:

Maybe remove the point about it not being affected by how many chunks are set to load (view distance in smp), since it seems to be the major parameter for the bug.

I just want to point out that I've been seeing this in 12w25b

I only recall seeing this since bug they added the feature that made the game 'more difficult' the longer you spend in an area. There was never a satisfactory answer for how the spawn algorithm was changed with this feature, but it is entirely possible this problem with spawn rates may be related. Just a thought.

uhh i have no idea why I'm putting a comment. What are we talking about people

Jack, I think they're talking about bugs.

I have exact same problem in 1.7.10 - Running my small server for me and friends on older laptop with core2duo and same problem - almost no hostile mobs, Its really severe problem becouse not even that the game is too easy but also mob traps dont spawn any mobs,

I am having this exact problem in 14w21b when I lower the render distance. I have a zombie pigman farm that was producing a steady stream of them regardless of render distance, then suddenly something changed and I no longer get a single spawn on a 44x44 platform with the distance set to 8. My system has an i5 overclocked to 4.1 GHz, minecraft is using about 500 MB of ram (I set the max to 6GB) and I am getting 120 FPS so I doubt that the computer not keeping up with the ticks is the problem. If I increase the render distance to 16, my FPS drops to about 40, and the problem goes away.

Not sure if it's the same problem but on our server we had the problem that no hostile mobs were spawning (since 1.7.4, normal spawning before that) except by mob spawners. In server.properties difficulty was 2 and spawn-monsters was true.
Eventually we found out that in the level.dat under Gamerules there was an entry doMobSpawning which was for some reason set to false. Changing that solved our problem.

The mobs don't/hardly spawn if the render distends is low.

I suspect that this happens because there is a mob cap.
cap = 70 * chunks_loaded / 256
There is also a rule that says mobs hostile mobs cant exist outside a radius of 120 block of all players.

Lets say there are 4 × 4 = 16 chunks loaded by 1 player. (very low render distends) Then the mob cap would be 4. These 4 mobs would spawn somewhere and will probably never be found.

Now lets say there are 16 × 16 = 256 chunks loaded by 1 player. (high render distends) Then the mob cap would be 70. How ever the rule that all mobs must be in a 120 block radius means that all of the 70 mobs will be relatively close. Making it seem like even more mobs have spawned.

What I suggest is to make the mobcap player dependent instead of chunk dependent. And just calculate how much of the 120 block radius overlaps with other players so you don’t get to many mobs to spawn if multiple players are in the same location.

Further more I believe that mobs can spawn in any of the 256 loaded chunks but only ~70% is within the loaded the 120 block radius. (when the player is at y=32 in a plains biome) But with the new 32 chuck render distends that will only be ~17% of the 280 mobs that are within the 120 block radius. So a lot of the mobs that have spawned will despawn immediately. Which creates a lot of server side lag as it will try to spawn so many mobs every game tick. How ever if mobs would attempt to spawn based of the location of a random player within the 120 block radius that would also reduce the sever load.

I hope this bug gets fix before 1.8.

Is this still an issue in 14w34d since the maybe related MC-55172 was fixed ?

I believe that MC-2536 is related/duplicate. I have almost no mobs spawning if my render distance is set to 8 or less. And also if I set the render distance to 10-15 and go to my mob farm (y=220 above a deep ocean) the entity counter goes nuts! The counter goes from 100 to 400 entities and back 10 times per second. it looks like multiple thousands of mobs are spawned and despawned each second. The mob spawning algorithm needs some rewriting. Edit: yes same behaviour in 14w34d.

I think this still happen in 14w34d.

I'm going to play a few more hours, but I'm almost sure the problem still persists.

This problem is still in the game. I changed my render distance to a higher value and my entity count tripled. While on a 3 chunck render distance and on Hard mode I went caving and there was 9 entities in total and I had none spawning in the caves.

Just did a little test: observed the spawn rates on 7 render distance and the entity count stayed around 40. Render distance up to 9 and in a minute was back up to 80.

Not sure if this is the same issue but similar. Very low spawn rates. I started my world in Beta 1.1? and since about 1.7 something the spawns have not compared to the ones I see online for farms or play. I directly copied an enderman farm and have been getting less than half the rates stated by highly reputable youtubers. Today I edited in a pigman farm from another save and the rates were non existent. To test I went to the 1.8 world that the farm was copied from and the spawns were in the hundreds. My beta world has been updated to 1.8. I don't have a weak pc. 7-8GB allocated, AMD 6-core 3.3 GHz, 64 bit java, Win 7 home premium. SSP, in the new 1.8 world, I am getting cant keep up warnings in the log but I am getting good spawns and am not breaking below 65 fps. (personal cap). In the updated old world there were no warnings saying I couldn't keep up. hope this helps.

As of 10/09/2014 in 1.8 single player survival on a machine with mid-range hardware, I am having the same problem. At night, you can walk through a plains biome (with LARGE BIOMES set) and almost never see a single enemy. I need string from spiders, for instance, and I am on day 11 and have seen only about 5 mobs at night total. This is really causing trouble. The game is approaching unplayable because I cannot get the resources I need from mobs. When night fell, I walked 300 blocks through a plains biome and literally saw 1 zombie, that's it. Has there been any update about when this will be addressed? Thanks so much! -Matthew

@Matthew: check you are on hard difficulty and then press F3 to see how many mobs are around you and be sure you have a rendering distance 8 or grater than 8.
Then type:
/tp @e[type=Zombie] ~ ~ ~
It will show you the coordinates of each zombie.

Is this still a concern in the current Minecraft version 1.8.1 Prerelease 3 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

I can still turn down my render distance below 10, so yes this problem still exists.

That does not answer my question.

Why not? That is the reason this problem exists.

The spawning algorithm as described on http://minecraft.gamepedia.com/Spawn had small changes between 1.6.4 and later versions, tweaks or bug fixes.
The part "In single player mode, the chunk count is 17×17 = 289" was not changed.

I made some tests on 1.6.4, 1.7.2, 1.7.4 and 1.8.1 pre3 on render distance 2 or tiny.
Since 1.7.4 the render distance will limit the MultiplayerChunkCache to 49 (7x7). Before used to be 225 (15x15) or greater.
As a consequence, since 1.7.4, on render distance 2, the maximum allowed mob cap is much lower.

The bug which I noticed initially was about mobs not spawning at all:
I prepared in creative mode a platform, for a witch farm, and after awhile I noticed that mobs stopped spawning not only on the platform but everywhere.
Later in several survival worlds, mobs were not spawning during night or the number was very low.
The spawning rate was not restored by changing the render distance.
It was restored by exit and loading the map again. I was watching the almost empty desert from a top of a mountain and after reload it was filled with mobs.
This bug I think was fixed.

I am also still experiencing this bug on 1.8.1 pre -3 but it seems that the spawns sort of "warm up" by that I mean that the entity count increases by one or two every few minutes up to a max of about 18 render distance is set to 16 chunks and holding about 50 fps

Have you tested that in a normal world and just checked your entity count in the F3 screen?

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...

@Jill S: " especially for mob traps built at high altitudes" ? If altitude is low, what happens?

" I seem to remember a server setting for this"
See http://minecraft.gamepedia.com/Spawn#Mob_spawning

In multiplayer, if the server.properties file has "view-distance=9" or below, mob spawning is severely reduced (or they de-spawn too quickly), and may result in the player encountering no mobs at all. Set the view distance to 10 or higher to ensure mobs spawn correctly.

I have the same problem. All the maps i've created in single player have low spawn rates of hostile mobs since 1.7.2... Please help :c

It would be nice if you attach screenshots with F3 info.

Everyone having problems rember the one most important rule: Never ever turn the render distance below 10! This will cause this problem for sure. I can't guarantee that it doesn't happen on 10 and above (but that would be a different issue), but it will definitely happen below 10!

Ioan Vira ok, I will post my computer characteristics and some screenshots with the problem. I hope that be usefull for you and usefull to fix the bug; and Code Raider, well, I play with 6 chunks of distance, I will change it to 10 and I tell you such. Thanks everybody. ^^

@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.

If you want to do any test on this issue, please do so on render distance 10 or above, otherwise the test will not show anything about a potential other issue unrelated to the render distance problem.
Also do not use MCEdit for tests with mobspawning, I already had problems with it messing up stuff with the mobspawning. I don't exactly know what the problem with that is (That's most likely a MCEdit problem though).

@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.

Without using MCEdit as well? (Just use some world presets.)

I find the MCEdit hint interesting.
@Jill S : On the MCEdit modified platform, where the altitude is 238, can you please try placing some blocks in the area where you expect mobs to spawn? Just to see if the game behavior changes after you modified the chunk manually.
And another thing you can try is to increase the altitude gradually to see where the problem starts to occur. Maybe you notice something interesting during these experiments.
Add some screenshots too 🙂

@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.

@Jill S : mob spawners ignore the maximum mob cap.

As stated on wiki, game tries to spawn mobs 20 times per second.
http://minecraft.gamepedia.com/Spawn#Mob_spawning

"If the pack location is suitable, [...]"

But the game will not calculate for each chunk 20 times per second the altitude. It somehow knows the altitude where it should test for suitable locations. Possibly the altitude is calculated

• at chunk load (here MCEdit I guess may disturb things)

• and should be adjusted during the day-night cycle or light update

If mobs spawn fine on a new survival mode map, you can assume you have found no bug.

Add screenshots with F3 info to show the mob count as proof.
Else developers will not believe you.

If anyone knows how the game find the altitude, please share some info 🙂

I think this bug as originally described vanished in
https://mojang.com/2014/05/minecraft-snapshot-14w20a/

A new bug should be opened for other occurrences.

I literally just doublechecked that post, and it doesn't say anything regarding this bug report...

In my opinion, this is one of the most important bugs in Minecraft. It affects gameply directly. Minecraft 1.7.4 was released almost a year ago... But the problem still persist. Maybe we have to open a new bug report.

@Sonic You are correct. They just made some changes in that release which seem related to spawn : "Update: Snapshot 14w20b has been released to fix mobs not spawning naturally." I think they unintentionally fixed this bug or made it harder to reproduce.

@People: The original description is "When I updated to the new 1.7.4 version of Minecraft It seemed normal. At first I had reasonable spawn rates, but for some reason after a night or two in game I got 5 mobs at most.".
The problem was not occurring fast and was not easy to reproduce. You had to play the game for awhile and maybe it was happening, maybe not.

@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.

That doesn't mean it's not an MCEdit problem. It would be interesting if it wasn't though, as they "fixed" the lc value problem for mobspawning in 1.8.

@Jill S Try Y33. I guess the spawning will be low.
I will stop following this issue. Good luck.

@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.

This is quite literally, the only bug keeping me from playing minecraft. I don't have much of a creative kind of mind so I like the survival aspect the most in minecraft. But when there are no mobs spawning, there's no point in playing survival. I really want this bug to get fixed.

@Jill S That is exactly why I said do not use MCEdit. It messes up spawning!

@Shi-Ron Morman Make sure you are playing with at least render distance 10 at all times.

@Shi-Ron Morman I totally agree with you. I don't mind if beds have a worng texture, or if there is a shadow bug. This kind of bugs don't affect gameplay at all. But this issue...

Still an issue in 1.8.1.

I feel like someone accidentally switched the spawn rate between hostile mobs and squid.
Because is it just me or a squid spawning like crazy?

Yeah, still a problem in 1.8.1, no mob systems work for me and caving is just way too easy.

I don't know if this help, bit I've been trying a long with the mob spawning and I saw ome strange behavior on mob. Like mob spawing when I'm at height 1000. The way I test this is, First set to Peaceful, /tp @p ~ ~1000 ~ , set to Easy/Normal/Hard mode and then /tp @e Player.
That could be the answer to the lack of hostile mob, mobs counting to the mob cap further 1000 blocks away?
I don't think this behavior it's normal at all and it's pretty sad that I can't even make any mob farm because this issue I hope they can fix it as soonest possible.

An update to my previous comment. This only happened when the render distance is 9 or less in 10 or more the mobs have a normal spawning.

I can confirm what Keneth said, I have been having similar problems on my HP Envy 6. I tried turning the view distance to 10 like you suggested and that also made spawns normal, however it causes a fair amount of strain from having the blocks loaded.

Does anyone know of any 1.8 mods which counter this bug? Mods which increase mob spawning?

You could always just have some command blocks spawning a few extra mobs.

@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. 🙂

Thanks for the advice guys, much appreciated 🙂

This should be renamed to something like: "Low mob spawn rates on low render distances"

Done.

I appear to have this problem with 7 chunks render distance, and I just got a powerful computer. It doesn't seem to happen all nights, but I've noticed a lower spawn rate of mobs per night as usual.

This is affecting realms servers as I have a sky mob spawner which currently generates nothing, this makes using realms rather difficult currently.

This urgently needs a fix in Realms to increase the render distance on the server.

Same problem in minecraft_server 1.8 with Linux (none) 3.2.0-4-686-pae #1 SMP Debian 3.2.65-1+deb7u1 i686
and Java :
OpenJDK Runtime Environment (IcedTea6 1.13.6) (6b34-1.13.6-1~deb7u1)
OpenJDK Server VM (build 23.25-b01, mixed mode)
the render distance is set to seven, and the heights don't change anything for spawn.

Still waiting for this to get fixed 😞 Under 10 render distance hostile mob RARELY spawns at night/ mob spawn underground.
Below 10 render distance most mob-spawn farming gets broken
And some people can't decrease more fps to set their render distance 10 and above.

This affects all Realms servers as well, things like "sky spawners" do not work because of this.

Confirming this problem still exists in 1.8.9.
I have a sky spawner with a spawning pad at level 190 and no mobs would appear while in Realms, but when I loaded the map up in single player the mobs appeared.

Here too, still having this bug in 1.8.9. I was building a sky spawner on my Realms server at Y=180 above the ocean and no mobs spawn, even though some annoyed me while building it. When I relog into the world sometimes 4 or 5 mobs spawn inside the spawner, but no more. When I built the spawner in a flat creative single player world, it worked like a charm.