"Failed to load Premain-Class manifest attribute" while trying to get the size of an object using java agent

Question

When i try to run a java program (java -javaagent:size.jar ObjectSizeTest) i get the following error:

Failed to load Premain-Class manifest attribute from D:\workspace\ObjectSizeTest\size.jar
Error occurred during initialization of VM
agent library failed to init: instrument

Here is ObjectSizeTest's code:

public class ObjectSizeTest {
    public static void main(String[] args) {
        String s = new String("sai");
        System.out.println(ObjectSizeFetcher.getObjectSize(s));
    }
}

MANIFEST.MF (for size.jar):

Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)

Premain-Class: ObjectSizeFetcher

and here is ObjectSizeFetcher's code:

import java.lang.instrument.Instrumentation;

public class ObjectSizeFetcher {
    private static Instrumentation instrumentation;

    public static void premain(String args, Instrumentation inst) {
        instrumentation = inst;
    }

    public static long getObjectSize(Object o) {
        return instrumentation.getObjectSize(o);
    }
}

You get the following error...and...? (You didn't ask a question.) — JasCav, Feb 15 '10 at 14:32
Can you post the Manifest file, I think your Premain-Class in the manifest file is not fully qualified or it is unable to find that class. — Teja Kantamneni, Feb 15 '10 at 14:34
I solved the issue. The manifest.mf file has a space before the Premain-Class which is not required — java_geek, Feb 16 '10 at 18:52
I had this with JaCoCo. The reason was that it's Maven jar has the jacocoagent.jar packed inside. So I needed to do dependency:unpack to a tmp dir and use from there. — Ondra Žižka, Jan 20 '12 at 15:51

score 10 · Answer 1 · answered Sep 01 '11 at 12:11

10

Make sure you have give full java path of the class containing the pre-main method. for example like this org.eclipse.anotherpckg.ObjectSizeFetcher. Secondly there must be a space before the name and carriage return at the end. for example

Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)
Premain-Class: org.eclipse.package.ObjectSizeFetcher

The last line is due to carriage return.

answered Sep 01 '11 at 12:11

user758867

121
1
5

3

It's not visible in this snippet, but new line at the end of file is indeed necessary. – Juraj Misur Oct 11 '14 at 15:56

score 6 · Answer 2 · answered Jun 04 '16 at 12:46

6

You should add in MANIFEST.MF:

Premain-Class: org.your.package.ObjectSizeFetcher + new line

insted

Premain-Class: ObjectSizeFetcher

answered Jun 04 '16 at 12:46

Max Gabderakhmanov

912
1
18
36

score 2 · Answer 3 · answered Feb 07 '14 at 09:56

2

It is an issue with the jar command itself. jar command must be used with cfm attributes, to include customized MANIFEST.MF, otherwise jar will create one file and insert its own contents which do not include the PreMain-Class attribute as we mention in customized manifest.mf file.

answered Feb 07 '14 at 09:56

maruthy

21
1

I'm logging in just to upvote this answer as `cfm` (especially the `m`) is exactly what solved my problem. The claim of having to use "new line" in the manifest file in other answers is pure wrong. – GJ. Mar 08 '23 at 03:08

score 0 · Answer 4 · answered May 15 '19 at 08:26

0

just run java size.jar ObjectSizeTest the problem is caused by java agent it has a tranformer class.

answered May 15 '19 at 08:26

jackson

16
3

"Failed to load Premain-Class manifest attribute" while trying to get the size of an object using java agent

4 Answers4

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