I've been running Minecraft on Ubuntu for a couple days but I am often encountering the same problem. I started playing from the browser but after about 15 minutes it would freeze or lag so bad that I could not continue. I then learned to launch it from command line and continued to have the same problem. With the command line still open it gave me this warning:

"WARNING: Can't keep up! Did the system time change, or is the server overloaded?"

Figuring it may be a memory allocation issue, as was mentioned in another question, I tried the launch script provided in the answers there, which was

java -Xmx2096M -Xms1048M -cp minecraft.jar net.minecraft.LauncherFrame

This did not solve my problem, the warning is still occurring and I even had a little more trouble getting it to open with this one.This computer has run Minecraft before, when it had Windows, so I think the machine itself is powerful enough to do it. Oh, and I'm running Open JDK 7 for java.

Suggestions on how I can get this up and running for longer than 15 minutes?

  • Just to know, have you tries running minecraft with just the java in front of it. I mean right click the minecraft.jar file and open it with openjre. – Luis Alvarado Dec 3 '12 at 20:17

Try using Oracle instead of JDK?

In console,

sudo apt-get purge openjdk*

removes openjdk

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

installs oracle

  • For the 1+ year testing Minecraft with both (OpenJDK and Oracle JDK) I have not found a single difference between them when using Minecraft. Minecraft runs perfect in both so I have never understood the need to purge the open version for the close one when trying to fix Minecraft. If you could give me an example because like I said, Minecraft 1.2.x up to the latest and no problem has arise from using openjdk. Most problems are the gl libraries that need downloading/overwrite, Hardware not enough or a Minecraft option inside the game. – Luis Alvarado Dec 3 '12 at 20:15
  • Okay I'll trust your word over mine on that. However, as a last resort it could be worth a shot. – Henry Gibson Dec 3 '12 at 20:38
  • Yeah, I am not saying not to install, what I am saying is to give OpenJDK at least a chance. The thing is, since the main devs of Minecraft have maybe tried Oracle only (Or maybe tried OpenJDK in a bad moment) then they normally recommend Java, hence the amount of Oracle recommendations I see here for Minecraft. There were some issues that only happened with OpenJDK but not with Oracle, but since 12.04 (And even with an update in 11.10), users can play Minecraft, even the 1.4.5 with OpenJDK. So don't worry about my rant, but it is more a worry about bad publicity OpenJDK is getting. – Luis Alvarado Dec 3 '12 at 20:54

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