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

[Ioi Lam]

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

As far as I can tell, the intention is -- if UseAppCDS is not enabled, 
load classes only for the boot loader.

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.

What do you think?

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
>