RFR(T) : 8195060 : vm/mlvm/anonloader/stress/byteMutation intermittently times out

[Igor Ignatyev]

in its current state, the test changes 4 random bytes to random values, and w/ <clinit> being[1] I don't see it possible to get valid classfile w/ an infinite recursion in <clinit>.

Thanks,
-- Igor

[1]
>   static {};
>     descriptor: ()V
>     flags: (0x0008) ACC_STATIC
>     Code:
>       stack=6, locals=0, args_size=0
>          0: ldc           #8                  // String %65500c%X
>          2: iconst_2
>          3: anewarray     #9                  // class java/lang/Object
>          6: dup
>          7: iconst_0
>          8: bipush        99
>         10: invokestatic  #10                 // Method java/lang/Character.valueOf:(C)Ljava/lang/Character;
>         13: aastore
>         14: dup
>         15: iconst_1
>         16: invokestatic  #11                 // Method vm/mlvm/share/Env.getRNG:()Ljava/util/Random;
>         19: invokevirtual #12                 // Method java/util/Random.nextLong:()J
>         22: invokestatic  #13                 // Method java/lang/Long.valueOf:(J)Ljava/lang/Long;
>         25: aastore
>         26: invokestatic  #14                 // Method java/lang/String.format:(Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;
>         29: putstatic     #2                  // Field theDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrumIsTheDrum:Ljava/lang/String;
>         32: return
>       LineNumberTable:
>         line 31: 0
>         line 32: 10
>         line 31: 32

> On Feb 13, 2019, at 9:28 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> 
> Can it randomly generate infinite recursions in <clinit> method too so your fix would be not enough? Or only <init>?
> 
> Thanks,
> Vladimir
> 
> On 2/12/19 7:20 PM, Igor Ignatyev wrote:
>> http://cr.openjdk.java.net/~iignatyev/8195060/webrev.00/
>>> 2 lines changed: 0 ins; 0 del; 2 mod;
>> Hi all,
>> could you please review this one-line patch for vmTestbase/vm/mlvm/anonloader/stress/ tests? the goal of these tests is to check that loading of anonymous classes won't lead to a crash and/or a hang, byteMutation test uses a randomly changed class file, which in some cases might lead to infinite recursions in <init> method. as the tests don't need to create an instance of loaded anonymous class to achieve their goal, the patch replaces Class::newInstance call w/ Unsafe::ensureClassInitialized to guarantee that we try to load, link and initialize classes.
>> webrev: http://cr.openjdk.java.net/~iignatyev/8195060/webrev.00/
>> JBS: https://bugs.openjdk.java.net/browse/JDK-8195060
>> testing:
>> - vmTestbase/vm/mlvm/anonloader/stress/ tests
>> - manually verified that the tests still can fail by running w/ Xverify:none
>> Thanks,
>> -- Igor