WarmRoast - a JVM CPU sampling tool to figure out why a MC server lags

I wrote a simple web-based JVM CPU sampling tool the other night called WarmRoast, which I find quicker to use and easier to explain than other profilers.

What it does: It tells you precisely what your server is doing, on average. If you expand out the nodes, you might find, for example, that EntitySheep consumes 24.56% of your server CPU. That might indicate, for example, that your friend has been secretly harboring a large sheep following deep under his "country home" for the past three months. While it is definitely a bit cryptic, poking around enough will let you become familiar with Minecraft's internals, at least to some degree.



Features

• Open source and easy to use!
• Adjustable sampling frequency.
• Supports loading MCP mappings for deobfuscating class and method names (for vanilla and other servers).
• Web-based — perform the profiling on a remote server and view the results in your browser.
  • Collapse and expand nodes to see details.
  • Easily view CPU usage per method at a glance.
  • Hover to highlight all child methods as a group.
  • See the percentage of CPU time for each method relative to its parent methods.
  • Maintains style and function with use of "File -> Save As" (in tested browsers).

Requires: Java 7 JDK and SSH/console/desktop access to your server.

Get WarmRoast

• Download/usage: https://github.com/sk89q/warmroast/blob/master/README.md
• Source code: https://github.com/sk89q/warmroast
• WarmRoast tutorial (basic)
• My guide on server performance

 

This looks brilliant! Nice work!

 

That's briliant! You keep on amazing me sk89q

 

sk89q

Have you ever made anything that isn't legendary!

This is awesome

 

Looks great!

 

Good job sk!

 

This would be great for me, but I'm confused on how I would use this if I have my server at a datacenter? This is an amazing idea and will definitely help me.

 

Too bad I'm on shared hosting. Would the license allow companies that sell shared hosting to make this available to their clients?

 

I'm trying to run this now but getting the following stack trace with oracle jvm 7:

Code:

Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/tools/attach/AttachNotSupportedException
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2451)
        at java.lang.Class.getMethod0(Class.java:2694)
        at java.lang.Class.getMethod(Class.java:1622)
        at sun.launcher.LauncherHelper.getMainMethod(LauncherHelper.java:494)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:486)
Caused by: java.lang.ClassNotFoundException: com.sun.tools.attach.AttachNotSupportedException
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        ... 6 more

any tips?

 

I would guess that you have installed the JRE, and not the JDK. The later one is needed for WarmRoast since it uses some tools provided with it.

 

that sounds about right. I did only have the JRE installed, but I've since also installed the jdk and having the same issue. I think at this point i'm launching it wrong, or possibly not indicating WHERE the jdk is to be found. though I'm really not sure.

solved, though probably not ideally, i was forced to run this with:

java -cp /path/to/tools.jar:warmroast.jar com.sk89q.warmroast.WarmRoast

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Thanks, everyone.

You need some way to run your own programs, which is commonly through SSH for Linux systems, or through command prompt via RDP for Windows.

Then follow the instructions here:
https://github.com/sk89q/warmroast/blob/master/README.md

Yes, it would allow for that.

 

Very useful, thanks for making this.

 

That looks very good I like your UI setup!

 

when i want to choose the VM i get this msg:

 

The tool itself looks very nice, but how is this any different from JVisualVm, which is built in the Oracle JDK

 

1. Run under the same user.
2. Use the Oracle JDK/JRE.

JVisualVM isn't usable over a web interface.

 

i have oracle java 1.7_25 JDK and JRE but when i do:

i get:

 

Code:

-Djava.library.path=/usr/lib/jvm/jdk1.7.0_25/bin

needs to be

Code:

-Djava.library.path=/usr/lib/jvm/jre/jdk1.7.0_25/bin

 

you mean "/usr/lib/jvm/jdk1.7.0_25/jre/bin"?

Code:

java -Djava.library.path=/usr/lib/jvm/jdk1.7.0_25/jre/bin -cp /usr/lib/jvm/jdk1.7.0_25/lib/tools.jar:warmroast.jar com.sk89q.warmroast.WarmRoast --thread "Server thread"

but igot the same error

Code:

Exception in thread "main" java.lang.UnsatisfiedLinkError: no attach in java.library.path
        at java.lang.ClassLoader.loadLibrary(Unknown Source)
        at java.lang.Runtime.loadLibrary0(Unknown Source)
        at java.lang.System.loadLibrary(Unknown Source)
        at sun.tools.attach.LinuxVirtualMachine.<clinit>(LinuxVirtualMachine.java:336)
        at sun.tools.attach.LinuxAttachProvider.attachVirtualMachine(LinuxAttachProvider.java:78)
        at com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:255)
        at com.sk89q.warmroast.WarmRoast.main(WarmRoast.java:282)

 

Does /usr/lib/jvm/jdk1.7.0_25/jre/bin exist? If so, what is in it?

 

http://abload.de/image.php?img=screenshotat2013-07-1yms6h.png

 

sk89q How would I define the path on Windows? It doesn't accept defining a drive letter

 

Excellent work with this, thank you!

 

Can we get a better usage guide please?

 

This is great!

 

It should let you define a drive letter. Make sure that you're splitting paths with ; and not : on Windows.

Where are you getting stuck at?

 

I've corrected that issue, however now I get the following error:

Could not find or load main class com.sk89q.warmroast.WarmRoast

I'm using the latest Java JDK 7 from Oracle site. Sorry

 

sk89q Step 3, maybe you can put an example up?

 

I get warmroast running, however, the website doesn't show any threads. I do have jdk, and it loads without errors, prompts me to pick the .jars that are running, or the "Server Thread". I pick any, and the website pulls up, with now thread information.