RFR(S): 8193434: [GRAAL] Graal classes are not loaded with -Xshare:dump

[Ioi Lam]

On 2/27/18 5:38 PM, Calvin Cheung wrote:
> Hi Ioi,
>
> Thanks for taking a look.
>
> On 2/27/18, 4:30 PM, Ioi Lam wrote:
>> Hi Calvin,
>>
>> I think the CNFE is caused by this code (in the "before" version):
>>
>> 1054 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* 
>> class_name,
>> 1055 Handle class_loader,
>> 1056 Handle protection_domain,
>> 1057 ClassFileStream* st,
>> 1058 TRAPS) {
>> 1059 #if INCLUDE_CDS
>> 1060   ResourceMark rm(THREAD);
>> 1061   if (DumpSharedSpaces && !class_loader.is_null() &&
>> 1062       !UseAppCDS && strcmp(class_name->as_C_string(), "Unnamed") 
>> != 0) {
>> 1063     // If AppCDS is not enabled, don't define the class at dump 
>> time (except for the "Unnamed"
>> 1064     // class, which is used by MethodHandles).
>> 1065 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), 
>> class_name->as_C_string());
>> 1066   }
>> 1067 #endif
> Yes, I wrote a comment in the bug report yesterday.
>>
>> As far as I can tell, the intention is -- if UseAppCDS is not 
>> enabled, load classes only for the boot loader.
> Right.
>>
>> However, when -XX:+UseJVMCICompiler is enabled in the command-line 
>> during dumping, we get this:
>>
>> $ java -Xshare:dump -Xlog:cds,cds+hashtables 
>> -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=./test.jsa 
>> -Xbatch -XX:+UnlockExperimentalVMOptions -XX:+EnableJVMCI 
>> -XX:+UseJVMCICompiler
>>
>> java.lang.ClassNotFoundException: 
>> org/graalvm/compiler/hotspot/HotSpotGraalJVMCIServiceLocator
>>     at 
>> java.lang.ClassLoader.defineClass2(java.base at 11-internal/Native Method)
>>     at 
>> java.lang.ClassLoader.defineClass(java.base at 11-internal/ClassLoader.java:1086)
>>     at 
>> java.security.SecureClassLoader.defineClass(java.base at 11-internal/SecureClassLoader.java:206)
>>     at 
>> jdk.internal.loader.BuiltinClassLoader.defineClass(java.base at 11-internal/BuiltinClassLoader.java:760)
>>     at 
>> jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(java.base at 11-internal/BuiltinClassLoader.java:681)
>>     at 
>> jdk.internal.loader.BuiltinClassLoader.findClass(java.base at 11-internal/BuiltinClassLoader.java:562)
>>     at 
>> java.lang.ClassLoader.loadClass(java.base at 11-internal/ClassLoader.java:611)
>>     at java.lang.Class.forName(java.base at 11-internal/Class.java:450)
>>     ...
>>
>>
>> With "-XX+UseAppCDS -Xlog:class+load=debug", we can see this class is 
>> loaded by the platform loader:
>>
>>
>> [0.325s][info ][class,load] 
>> org.graalvm.compiler.hotspot.HotSpotGraalJVMCIServiceLocator source: 
>> jrt:/jdk.internal.vm.compiler
>> [0.325s][debug][class,load]  klass: 0x00000008c0083c30 super: 
>> 0x00000008c00734c8 loader: [class loader 0x00007f30344e5870 a 
>> 'jdk/internal/loader/ClassLoaders$PlatformClassLoader'{0x000000041105cbf0}] 
>> bytes: 1443 checksum: 8dae8ade
>>
>>
>> I think instead of using the _force_init_jvmci_runtime, which allows 
>> these classes to be loaded only during a portion of the dump time, a 
>> better fix would be to remove the above "if" block altogether. I 
>> think if UseAppCDS is not true, 
>> SystemDictionary::combine_shared_dictionaries() won't be called, so 
>> any non-boot classes will be left out from the CDS archive, which is 
>> what you want.
> I tried setting breakpoint in 
> SystemDictionary::combine_shared_dictionaries() and the debugger 
> stopped there without enabling UseAppCDS. 

How about adding a check like this:

void SystemDictionary::combine_shared_dictionaries() {
   assert(DumpSharedSpaces, "dump time only");
   if (UseAppCDS) {
     Dictionary* master_dictionary = 
ClassLoaderData::the_null_class_loader_data()->dictionary();
     CombineDictionariesClosure cdc(master_dictionary);
     ClassLoaderDataGraph::cld_do(&cdc);
   }


> My current proposed change should have the least impact on CDS 
> (without enabling UseAppCDS).
> For getting rid of those "Preload Warning" noted by Vladimir, I think 
> I can leave the _force_init_jvmci_runtime setting; i.e. not resetting 
> it to false at the end of force JVMCI runtime init. This is what I had 
> in my first version:
> http://cr.openjdk.java.net/~ccheung/8193434/webrev.00/
I think the use of _force_init_jvmci_runtime feels like an ad-hoc 
solution. The existing code is already hard to understand:

1061   if (DumpSharedSpaces && !class_loader.is_null() &&
1062       !UseAppCDS && strcmp(class_name->as_C_string(), "Unnamed") != 
0) {

Our problem here is to make sure that the Java-based class loaders runs 
correctly during dump time. In the future, if more non-boot classes are 
loaded when running the Java-based class loaders, this "if" condition 
will get more and more complicated.

I think it's much cleaner to modify combine_shared_dictionaries(). That 
way we can ensure that the Java-based loaders can run correctly, and 
also make sure that only boot classes are archived when UseAppCDS is false.

Thanks
- Ioi
>>
>> What do you think?
> I think the current fix with the "Preload Warning" is ok; it means 170 
> classes won't be in the archive.
>
> thanks,
> Calvin
>>
>> Thanks
>> - Ioi
>>
>>
>>
>> On 2/27/18 11:01 AM, Calvin Cheung wrote:
>>> bug: https://bugs.openjdk.java.net/browse/JDK-8193434
>>>
>>> webrev: http://cr.openjdk.java.net/~ccheung/8193434/webrev.01/
>>>
>>> java -Xshare:dump -Xlog:cds,cds+hashtables 
>>> -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=./test.jsa 
>>> -Xbatch -XX:+UnlockExperimentalVMOptions -XX:+EnableJVMCI 
>>> -XX:+UseJVMCICompiler -Djvmci.Compiler=graal
>>>
>>> The above command causes the CNFE to be thrown in 
>>> SystemDictionary::resolve_from_stream() during CDS dump time.
>>> The proposed change is to add a _force_init_jvmci_runtime flag which 
>>> is set at the beginning of JVMCIRuntime::force_initialization() and 
>>> reset at the end of the initialization. The flag will be checked in 
>>> SystemDictionary::resolve_from_stream() so that it will not throw 
>>> CNFE during the eager initialization of JVMCI runtime during vm init.
>>>
>>> The proposed change passed hs-tier1 through hs-tier3 testing on 
>>> linux-x64, windows-x64, sparcv9, and Mac OS X.
>>>
>>> thanks,
>>> Calvin
>>>
>>