I'm attaching to this bug a self contained example where you can see both type of errors.
The example includes all source files needed and scripts to build and run.
You will need both Java 1.6 and Java 1.7 installed on your machine to run the full test and see the difference.
To run the test:
1. Extract the attached jatest.zip file to your machine.
2. Edit the files test1.6.bat and test1.7.bat and adjust the paths to your Java 1.6 and 1.7 installations respectively.
If you are running on a non-windows platform you can easily translate these scripts to the target platform.
3. Run both test1.6.bat and test1.7.bat. These two scripts build and run the same test with Java 1.6 and Java 1.7 respectively.
4. Each x script (x= 1.6, 1.7) does the following:
Compiles the source files.
Creates a testx.jar file.
Runs the class TraceJar against the testx.jar.
TraceJar uses javaassist to insert simple print statements into each method using insertBefore and insertAfter. It creates a new testxT.jar
Runs the Main test class against the generated testxT.jar.
The test tries to load the two test classes Test1 and Test2 and then also tries to run through some of their methods.
You can see that all this works fine with Java 1.6 but fails with Java 1.7.
See below the output with Java 1.6 vs. the output with Java 1.7.
Note that getting the second type of error - Bad return type - is quite easy. All it takes is a simple method like the one in Test2.
The first type of error - Inconsistent stackmap frames - seems to occur only for a very specific code pattern as in Test1. Changing that code even slightly results in either a valid class or in the Bad return type error.
Output with Java 1.6:
...
Running test with jar16T.jar
before method Main.main(java.lang.String[]), params=[[Ljava.lang.String;@1f33675]
before method Main.loadClass(java.lang.String), params=[Test1]
loading test class Test1
class was loaded succesfuly
after method Main.loadClass(java.lang.String), retval=null
before method Main.loadClass(java.lang.String), params=[Test2]
loading test class Test2
class was loaded succesfuly
after method Main.loadClass(java.lang.String), retval=null
before method Main.runTest1()
before method Test1.f(Info), params=[Info@19ee1ac]
before method Test1.createHolder()
after method Test1.createHolder()
before method Info.createChild(Holder), params=[Holder@1befab0]
after method Info.createChild(Holder)
before method Child.init()
after method Child.init(), retval=null
after method Test1.f(Info)
before method Test1.f(Info), params=[SubInfo@13c5982]
before method Test1.createHolder()
after method Test1.createHolder()
before method SubInfo.createChild(Holder), params=[Holder@1186fab]
after method SubInfo.createChild(Holder)
before method Child.init()
after method Child.init(), retval=null
after method Test1.f(Info)
after method Main.runTest1(), retval=null
before method Main.runTest2()
before method Test2.f()
after method Test2.f()
after method Main.runTest2(), retval=null
after method Main.main(java.lang.String[]), retval=null
Output with Java 1.7:
...
Running test with jar17T.jar
before method Main.main(java.lang.String[]), params=[[Ljava.lang.String;@1489c06]
before method Main.loadClass(java.lang.String), params=[Test1]
loading test class Test1
failed to load class
java.lang.VerifyError: Inconsistent stackmap frames at branch target 68 in method Test1.f(LInfo;)LParent; at offset 61
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at Main.loadClass(Main.java:16)
at Main.main(Main.java:7)
after method Main.loadClass(java.lang.String), retval=null
before method Main.loadClass(java.lang.String), params=[Test2]
loading test class Test2
failed to load class
java.lang.VerifyError: Bad return type in method Test2.f()LParent; at offset 22
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at Main.loadClass(Main.java:16)
at Main.main(Main.java:8)
after method Main.loadClass(java.lang.String), retval=null
before method Main.runTest1()
failed to run test1
java.lang.VerifyError: Inconsistent stackmap frames at branch target 68 in method Test1.f(LInfo;)LParent; at offset 61
at Main.runTest1(Main.java:27)
at Main.main(Main.java:9)
after method Main.runTest1(), retval=null
before method Main.runTest2()
failed to run test2
java.lang.VerifyError: Bad return type in method Test2.f()LParent; at offset 22
at Main.runTest2(Main.java:38)
at Main.main(Main.java:10)
after method Main.runTest2(), retval=null
after method Main.main(java.lang.String[]), retval=null
Bug
Major
JASSIST-163 RuntimeSupport.find2Methods a perf hotspot when proxy's methods are called at higher concurrency
