MC-1628Minecraft runs out of memory when you switch a lot between worlds
After switching between worlds like 25 times, minecraft runs out of memory
I created 2 new superflat worlds with the "Redstone Ready" template.
Each time i switch to another one of these, the game consumes 60 - 100 mb more ram!
What I expected to happen was...:
I expected to be able to switch between singleplayer worlds as much as i want
What actually happened was...:
Minecraft starts using more and more ram, making it crash because it's out of memory
Steps to Reproduce:
1. Leave current world
2. Join another world
3. Leave this world
4. Join another world
And so on like 25-35 times until minecraft crashes
Environment
Mac OS 10.8.2
Java 1.6
Linked Issues
Created Issue:
Minecraft runs out of memory when you switch a lot between worlds
After switching between worlds like 25 times, minecraft runs out of memory
What I expected to happen was...:
I expected to be able to switch between singleplayer worlds as much as i wantWhat actually happened was...:
Minecraft starts using more and more ram, making it crash because it's out of memorySteps to Reproduce:
1. Leave current world
2. Join another world
3. Leave this world
4. Join another world
And so on like 25-35 times until minecraft crashesEnvironment
Mac OS 10.8.2
Java 1.6
- Unresolved
- Open
- Public
- Unconfirmed
- Memory OSX
- 1.4.2
After switching between worlds like 25 times, minecraft runs out of memory
What I expected to happen was...:
I expected to be able to switch between singleplayer worlds as much as i wantWhat
actuallyhappenedwas...:
Minecraft starts using more and more ram, making it crash because it's out of memorySteps to Reproduce:
1. Leave current world
2. Join another world
3. Leave this world
4. Join another world
And so on like 25-35 times until minecraft crashesAfter switching between worlds like 25 times, minecraft runs out of memory
I created 2 new superflat worlds with the "Redstone Ready" template.
Each time i switch to another one of these, the game consumes 60 - 100 mb more ram!What I expected to happen was...:
I expected to be able to switch between singleplayer worlds as much as i wantWhat actually happened was...:
Minecraft starts using more and more ram, making it crash because it's out of memorySteps to Reproduce:
1. Leave current world
2. Join another world
3. Leave this world
4. Join another world
And so on like 25-35 times until minecraft crashes
relates to
is duplicated by
relates to
Is this still a concern in the current Minecraft version 1.6.2 / Launcher version 1.1.2 ? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
is duplicated by
We are unable to reproduce this issue in 1.6.2, please join the discussion in MC-1628 and provide additional information there.
When joining a world or server, memory gets allocated but never released. When rejoining the same world/server, new memory is used anyways. Sometimes the space used seems to jump back down a little but it does not cancel out the new allocation. The RAM needed by the game after a couple of restarts seems to exceed the number specified by "f3". This also seems to happen when rejoining the same server over and over again.
I was able to "reproduce" it many times (as in: over the past months I sometimes had to restart minecraft to keep it from using swap space 
)
Sounds like a memory leak. This could happen due to loading worlds and all assets not being unloaded when leaving.
It's crazy, I know, but Minecraft does suffer from memory leaks.
The best course of action you can take at present would be restarting the game after the 20th time you've switched maps. Or, assuming that you are trying to transfer something from Creative to Survival, take photos of whatever you've built so you don't have to swap the maps so much.
I frankly think this will be a tough one to solve, as this (plus the other memory leaks) have not been resolved for a while now.
Yeah for me it's not too big of a problem that i have to restart minecraft after some switching, but it should not be necessary. Also it are just normal flat sandstone worlds with nothing special in them
Even with limited block types, there can be memory leaks in other areas. All games suffer from memory leaks, the question is how severe is the leak. Minor leaks can usually be ignored while major leaks need to be fixed as it can become overbearing on the system. That was one of the reasons for pulling back on 1.4.1 and instead releasing 1.4.2.
To make this bug report more complete, I would recommend the following:
Some new information about this bug.
I created 2 new superflat worlds with the "Redstone Ready" template.
Each time i switch to another one of these, the game consumes 60 - 100 mb more ram!
This is more than i expected to be.
I've noticed this recently in my 1.4.6 SMP world, however the problem happens to me when switching between the Overworld and the Nether.
Even standing still my javaw.exe's memory steadily climbs, though eventually it will stop until walking around a bit. Going into and out of the nether in one trip usually increases my memory consumption enough the game gets really choppy.
Another thing to note is that the mod Mystcraft is also affected by this, this means i cannot switch between ages much, which is really annoying as my resources are in the overworld but i am doing work in an age. Please fix this memory leak Mojang!
Wow..... here a list of my increasing ram:
280 Mb start Minecraft
630 Mb World 1
800 Mb World 2
910 Mb World 3
1030 Mb World 4
1190 Mb World 5
1280 Mb World 6
1310 Mb World 7 => here my computer starts to lag and i got 4 Gb RAM
@Alper Yetis: From where do you read the numbers and which parameters do you use for the JVM ?
Keep in mind that JVM always allocates RAM until exhausted, then the garbage collection kicks in.
I use always the default ( -Xms512m -Xmx1024m) and never run in memory issues, even when heavily switching worlds (single and multiplayer)
I was able to get win7 throw its own out of memory warnings simply due to minecraft 1.4.7 idling long enough on the background
(And I have 6G of RAM, normally idling at around 1.9GB used) Though that sounds more like a memory leak in the JVM itself (or some native code somewhere), not in Java code, as, like mentioned, Java itself does have its own allocation limit (and I have it at that safe 1GB, too).
(Edit
But with repeated world switching I could not get as fast leaking (at least not with 1.4.7); memory usage did slowly creep up, though, from about 700MB (JVM + java heap) to around 1.6GB after about 15 switches or reloads of the same world. First large growth, but in the end typically only 20-30MB per switch. Definitely not good anyway.
@[Mod] Kumasasa i read the numbers from the task manager (processes => javaw.exe) ... Normaly i also do not have problems with running out Memory, but these days i worked on a adventure map and had to copy my original world often to test new features but after 7-8 new world tests minecraft run out of Memory
Started minecraft with
leaving it running overnight, switched a lot of worlds (15 times, some single player, some multiplayer), memory for java.exe is now (according to taskmanager) oscillating around 1 GB .
Debug screen says
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
On 1.5 it still seems to be like I described for 1.4.7; starts around 700-800MB (total 'commit' reported by win7 tools), but quickly ramps upto around 1.7GB (with 1GB heap). After that, it seems go up and down a bit, but apparently very slowly up, average maybe 5-10MB per world load at most. At least I can not get it to leak so badly as described in the description, and I run out of new worlds to load. Thus, not an issue for me.
(Java's heap seemed to working just fine, not even getting past 600MB at any time.)
(I didn't check switching specifically between two superflats, though, but various flat worlds seemed to be easier on memory anyway.)
This could be Mac (or perhaps even Mac LWJGL, or hardware drivers) specific issue, not reproducible on windows 7.
I tested this again yesterday. The ram gain between world switches is smaller than it was before, but this is still an issue in the current version (1.5)
But if all these additional resources are unneccesary, then the garbagecollector should get rid of them. Right?
As long as the memory doesn't go over some limits, the GC won't kick in.
But: Did 1.5 run out of memory (with a crash) or did you just observe an increase in memory usage ? If the latter, that ticket can be resolved.
Another question: Do you use texture packs ? If yes, this issue may be related to
MC-11439It did crash with that nice out of memory screen. I threw away the report, will try to reproduce it today and i will post the report here.
Also, i am not using any texturepack. Just vanilla.
try doing it slower so you can switch more times
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
If so, please force a crash by pressing F3 + C for 10 seconds while ingame short before the memory is exausted and attach the crash report here.
No answer, assuming fixed in 1.6.2.
I tested today with 1.6.2 and there is everything allright with the RAM now
Ok. Fine.
RAM upon 1.6.2 startup: 240640k
After creating a world and leaving after 5 mins: 511228k - Slight Lag
Creation of a second world and leaving after 5 mins: 755,224k - Major Lag
Creation of a third world and leaving after 5 mins: 1063,384k - Unplayable Lag
Creation of a fourth world and leaving after 5 mins: 1370028k - The memory limit is default, 1024MB
CPU usage upon startup: 20-50% (1.3Ghz dual core, javaw.exe usage)
In-game: 70-95%
Old Usage using the 1.5.2 and lower launcher w/ 1.5.2: 10% on menu, 40% in-game
Evidently the memory leak isn't fixed in 1.6.2
Uploaded a forced crash
Callum Watson, Please don't use early access versions of Java.
Cannot confirm.
Did the same (created 5 worlds, exited each after 5-15 minutes)
Created 5 Worlds, see screenshots.
javaw.exe RAM usage at the end: 1076 M
Callum, were those memory usage numbers observed in an operating system tool, or in the client itself? If former, it is normal (I can easily reach 1.7G usage with java's max parameter set for 1G). If latter, there would be a bug in the JVM itself (not obeying the max parameter). (The maximum parameter specifies the java's maximum internal 'heap' size, not the maximum RAM the JVM can request from the operating system.)
Coming to think of it, as you have such a humble CPU (by modern standards), what is your system's total RAM amount?
Also note that there is currently a bug that puts weaker CPU's to knees (and dual-core 1.3GHz would be counted as weak in this context), related to zombie's pathing (
MC-17630)... Combine that with the increased need for garbage collection once the heap starts getting full (like during your 4th world), and bad performance can be expected. A good test to try would be run the game on peaceful difficult (no zombies to wreck the CPU...)Contrary to Kumasasa's request, I installed the latest development version of java, java 8, and found all the performance problems vanish. The cpu is still fairly high but the RAM stays low, and my fps stuck to vsync even whilst loading worlds.
I have the same problem. I changed 10 or 12 times between different worlds and Minecraft crashed.
Mac OS X 10.7.5. Java 1.6. Minecraft 1.6.2.
@Dídac Garcia: