Stack map does not match the one at exception handler about btrace

[DamianSheldon]

The source code of the BTraceTest class:

package com.github.damiansheldon.jvm.chapter4;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class BTraceTest {

	public static void main(String[] args) throws Exception {
		BTraceTest test = new BTraceTest();
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for (int i = 0; i < 10; i++) {
			br.readLine();
			
			int a = (int)Math.round(Math.random() * 1000);
			int b = (int)Math.round(Math.random() * 1000);
			
			System.out.println(test.add(a, b));
		}
	}

	public int add(int a, int b) {
		return a + b;
	}
}

The source code of the trace script:

import org.openjdk.btrace.core.annotations.*;
import static org.openjdk.btrace.core.BTraceUtils.*;

@BTrace
public class TracingAddMethod {
    @OnMethod(
        clazz="com.github.damiansheldon.jvm.chapter4.BTraceTest",
        method="add",
        location=@Location(Kind.RETURN)
        )
    public static void func(
        @Self com.github.damiansheldon.jvm.chapter4.BTraceTest instance,
        int a,
        int b,
        @Return int result
        ) {
            println("stacktrace...");
            jstack();
            println(strcat("arg a:", str(a)));
            println(strcat("arg b:", str(b)));
            println(strcat("result:", str(result)));
          }
}

There are also three warnings output at console, full log as follow:

Java HotSpot(TM) 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended
btrace WARNING: BTrace bootstrap classpath resource [ /Users/meiliang/Library/Application%20Support/VisualVM/2.1.3/modules/ext/btrace-boot.jar] does not exist
btrace WARNING: BTrace system classpath resource [/Users/meiliang/.sdkman/candidates/java/17.0.3-oracle/lib/tools.jar] does not exist.
r
[BTRACE] Failed to link probe handler: org/openjdk/btrace/runtime/auxiliary/TracingAddMethod.$btrace$org$openjdk$btrace$runtime$auxiliary$TracingAddMethod$func
java.lang.VerifyError: Stack map does not match the one at exception handler 61
Exception Details:
  Location:
    com/github/damiansheldon/jvm/chapter4/BTraceTest+0x0000000800d18800.func(Lcom/github/damiansheldon/jvm/chapter4/BTraceTest;III)V @61: getstatic
  Reason:
    Type 'com/github/damiansheldon/jvm/chapter4/BTraceTest' (current frame, locals[0]) is not assignable to 'com/github/damiansheldon/jvm/chapter4/BTraceTest+0x0000000800d18800' (stack map, locals[0])
  Current Frame:
    bci: @10
    flags: { }
    locals: { 'com/github/damiansheldon/jvm/chapter4/BTraceTest', integer, integer, integer }
    stack: { 'java/lang/Throwable' }
  Stackmap Frame:
    bci: @61
    flags: { }
    locals: { 'com/github/damiansheldon/jvm/chapter4/BTraceTest+0x0000000800d18800', integer, integer, integer }
    stack: { 'java/lang/Throwable' }
  Bytecode:
    0000000: b200 1ab8 0020 9a00 04b1 1222 b800 28b8
    0000010: 002c 122e 1bb8 0032 b800 36b8 0028 1238
    0000020: 1cb8 0032 b800 36b8 0028 123a 1db8 0032
    0000030: b800 36b8 0028 b200 1ab6 003f b1b2 001a
    0000040: 5a5f b600 43b2 001a b600 3fb1          
  Exception Handler Table:
    bci [10, 61] => handler: 61
  Stackmap Table:
    same_frame(@10)
    full_frame(@61,{Object[#2],Integer,Integer,Integer},{Object[#20]})

421

[jbachorik]

Hi, thanks for reporting this!
Would it be possible to share the source code of the BTraceTest class?

TBH, the type descriptor com/github/damiansheldon/jvm/chapter4/BTraceTest+0x0000000800cd4800 looks rather unusual and it would be good to know what is producing such type descriptors.

[jbachorik]

Unfortunately, even this reproducer does not reproduce for me. I tried BTrace 2.2.2 as well as trunk build they all work fine.

Here is my env, for comparison. The only difference I see is that I am using JDK 17.0.3.1 whereas you are using 17.0.3 - but AFAICT from the JDK release notes this difference should not affect anything.

> sw_vers 
ProductName:    macOS
ProductVersion: 12.4
BuildVersion:   21F79

> java -version
java version "17.0.3.1" 2022-04-22 LTS
Java(TM) SE Runtime Environment (build 17.0.3.1+2-LTS-6)
Java HotSpot(TM) 64-Bit Server VM (build 17.0.3.1+2-LTS-6, mixed mode, sharing)

Could you run this command on the trunk build of BTrace and attach here the file you should find at /tmp/btrace_test/com_github_damiansheldon_jvm_chapter4_BTraceTest.class? That should contain the bytecode of the handler class which is giving you this error.

java -javaagent:btrace-agent.jar=dumpClasses=true,dumpDir=/tmp/btrace_test,debug=true,script=TracingAddMethod.class com.github.damiansheldon.jvm.chapter4.BTraceTest

[DamianSheldon]

It very strange, I now can successfully trace with command: java -cp bin -javaagent:/Users/meiliang/Downloads/btrace-v2.2.2/libs/btrace-agent.jar=dumpClasses=true,dumpDir=/tmp/btrace_test,debug=true,script=bin/TracingAddMethod.class com.github.damiansheldon.jvm.chapter4.BTraceTest or btrace -cp bin <pid> bin/TracingAddMethod.class。

But BTrace plugin in VisualVM can still reproduce this issue.

VisualVM's version is : 2.1.3 (Build 220330); platform 20220209-2172674416。

I Start it with command: /Applications/VisualVM.app/Contents/MacOS/visualvm --jdkhome /Users/meiliang/.sdkman/candidates/java/17.0.3-oracle/。

BTrace plugin's version is:

Version: 2.1.0 Source: org-openjdk-btrace-visualvm.nbm

Here is the
com_github_damiansheldon_jvm_chapter4_BTraceTest.class.zip

[jbachorik]

Well, in VisualVM is still version 2.1.0 which is rather old (working on getting the current version to VisualVM UC soon with the maintainers - but in the meantime you can download the updated plugins from https://github.com/btraceio/btrace.visualvm/releases/tag/v2.2.2 and install them manually).

The generated probe class from the archive you sent looks fine (as expected).

If the problem is not reproducible in BTrace 2.2.2 or the trunk build I would close this issue. The 2.1.0 version is pretty outdated and there will be no updates to 2.1.* line.

[DamianSheldon]

Plugin from https://github.com/btraceio/btrace.visualvm/releases/tag/v2.2.2 can reproduce this issue.

First I uninstall, then restart VisualVM to reinstall. I think this can remove previous version plugin's effect.

I realize plugin's version 2.1.0 which is BTrace Workbench's version , its base on BTrace API 2.2.0.

I think previous installed plugin already is version 2.2.0.

I also did some other experiments, after btrace plugin cause this issue, I rerun the program from eclipse, then try to trace, btrace -cp bin <pid> src/com/github/damiansheldon/jvm/chapter6/TracingAddMethod.java will cause issue, but btrace -cp bin <pid> bin/TracingAddMethod.class not, java -cp bin -javaagent:/Users/meiliang/Downloads/btrace-v2.2.2/libs/btrace-agent.jar=dumpClasses=trueumpDir=/tmp/btrace_test,debug=true,script=bin/TracingAddMethod.class com.github.damiansheldon.jvm.chapter4.BTraceTest also not cause problem.

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