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  1. JDK
  2. JDK-8206963

[AOT] bug with multiple class loaders

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    • Subcomponent:
    • Resolved In Build:
      b15
    • CPU:
      generic
    • OS:
      generic

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        Description

        Kevin wrote:
        When a class is loaded, jvm try to iterate all aot code cache to find if it's a defined symbol of shared library. But it doesn't check class loader carefully, so a class in aot cache could incorrectly access class data in another loader . Please check my test case.

        cat sub1/T1.java
        public class T1{
          public int xadd(int a,int b){
            int r=a+b+T2.foo;
            System.out.println(r);
            return r;
          }
        }
        cat sub1/T2.java
        public class T2{
          public static int foo=300;
          public static void change(int newVal) {foo=newVal;}
        }

        compile them in sub1 directory and make a copy as sub2. Create a aot library for T1.class
        jaotc --output aot.so T1.class

        put the aot.so into project directory and create a test file

        cat Main.java

        import java.io.File;
        import java.lang.reflect.Constructor;
        import java.lang.reflect.Method;
        import java.net.URL;
        import java.net.URLClassLoader;
        public class Main{
            public static void main(String[] args)throws Exception{
                File file1=new File("./sub1");
                File file2=new File("./sub2");
                URL url1 = file1.toURI().toURL();
                URL url2 = file2.toURI().toURL();
                changeT2(url1); // run with loader1
                run(url2); // run with loader2
            }
            public static void changeT2(URL url) throws Exception{
                URL [] urls={url};
                URLClassLoader ucl = new URLClassLoader(urls);
                Class<?> c2 = ucl.loadClass("T2");
                Constructor<?> conc = c2.getConstructor();
                Object obj = conc.newInstance();
                Method m = c2.getMethod("change", int.class);
                m.invoke(obj, 0); // change T2.foo=0
            }
            public static void run(URL url) throws Exception{
                URL [] urls={url};
                URLClassLoader ucl = new URLClassLoader(urls);
                Class<?> c1 = ucl.loadClass("T1");
                Constructor<?> conc = c1.getConstructor();
                Object obj = conc.newInstance();
                Method m = c1.getMethod("xadd", int.class, int.class);
                m.invoke(obj, 0, 0);
            }
        }

        The whole project is like this:
        > ls -l *
        -rw-r--r-- 1 kuaiwei.kw users 108329 Jul 9 14:55 aot.so
        -rw-r--r-- 1 kuaiwei.kw users 1613 Jul 9 14:55 Main.class
        -rw-r--r-- 1 kuaiwei.kw users 1241 Jul 9 14:55 Main.java
        sub1:
        total 16
        -rw-r--r-- 1 kuaiwei.kw users 398 Jul 9 14:55 T1.class
        -rw-r--r-- 1 kuaiwei.kw users 118 Jul 9 14:55 T1.java
        -rw-r--r-- 1 kuaiwei.kw users 321 Jul 9 14:55 T2.class
        -rw-r--r-- 1 kuaiwei.kw users 103 Jul 9 14:55 T2.java
        sub2:
        total 16
        -rw-r--r-- 1 kuaiwei.kw users 398 Jul 9 14:55 T1.class
        -rw-r--r-- 1 kuaiwei.kw users 118 Jul 9 14:55 T1.java
        -rw-r--r-- 1 kuaiwei.kw users 321 Jul 9 14:55 T2.class
        -rw-r--r-- 1 kuaiwei.kw users 103 Jul 9 14:55 T2.java
        run without aot
        > java Main
        300

        run with aot
        > java -XX:+UseAOT -XX:AOTLibrary=./aot.so Main
        0

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                • Assignee:
                  kvn Vladimir Kozlov
                  Reporter:
                  kvn Vladimir Kozlov
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                  • Created:
                    Updated:
                    Resolved: