RFR: 8247666: Support Lambda proxy classes in static CDS archive

[Calvin Cheung]

On Wed, 30 Sep 2020 03:43:51 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Following up on archiving lambda proxy classes in dynamic CDS archive
>> ([JDK-8198698](https://bugs.openjdk.java.net/browse/JDK-8198698)), this RFE adds the functionality of archiving of
>> lambda proxy classes in static CDS archive.
>> When the -XX:DumpLoadedClassList is enabled, the constant pool index related to LambdaMetafactory that are resolved
>> during application execution will be included in the classlist. The entry for a lambda proxy class in a class list will
>> be of the following format:
>> `@lambda-proxy: <classname> <cp index>`
>> 
>> e.g.
>> `@lambda-proxy: test/java/lang/invoke/MethodHandlesGeneralTest 233`
>> `@lambda-proxy: test/java/lang/invoke/MethodHandlesGeneralTest 355`
>> 
>> When dumping a CDS archive using the -Xshare:dump and -XX:ExtraSharedClassListFile options, when the above
>> `@lambda-proxy` entry is encountered while parsing the classlist, we will resolve the corresponding constant pool
>> indices (233 and 355 in the above example). As a result, lambda proxy classes will be generated for the constant pool
>> entries, and will be cached using a similar mechanism to JDK-8198698.  During dumping, there is check on the cp index
>> and on the created BootstrapInfo using the cp index. VM will exit with an error message if the check has failed.
>> During runtime when looking up a lambda proxy class, the lookup will be perform on the static CDS archive and if not
>> found, then lookup from the dynamic archive if one is specified.  (Only name change (IsDynamicDumpingEnabled ->
>> IsCDSDumpingEnabled) is involved in the core-libs code.)
>> Testing: tiers 1,2,3,4.
>> 
>> Performance results (javac on HelloWorld on linux-x64):
>> Results of " perf stat -r 40 bin/javac -J-Xshare:on -J-XX:SharedArchiveFile=javac2.jsa Bench_HelloWorld.java "
>>    1:   2228016795  2067752708 (-160264087)      -----    377.760   349.110 (-28.650)      -----
>>    2:   2223051476  2063016483 (-160034993)      -----    374.580   350.620 (-23.960)      ----
>>    3:   2225908334  2067673847 (-158234487)      -----    375.220   350.990 (-24.230)      ----
>>    4:   2225835999  2064596883 (-161239116)      -----    374.670   349.840 (-24.830)      ----
>>    5:   2226005510  2061694332 (-164311178)      -----    373.512   351.120 (-22.392)      ----
>>    6:   2225574949  2062657482 (-162917467)      -----    374.710   348.380 (-26.330)      -----
>>    7:   2224702424  2064634122 (-160068302)      -----    373.670   349.510 (-24.160)      ----
>>    8:   2226662277  2066301134 (-160361143)      -----    375.350   349.790 (-25.560)      ----
>>    9:   2226761470  2063162795 (-163598675)      -----    374.260   351.290 (-22.970)      ----
>>   10:   2230149089  2066203307 (-163945782)      -----    374.760   350.620 (-24.140)      ----
>> ============================================================
>>         2226266109  2064768307 (-161497801)      -----    374.848   350.126 (-24.722)      ----
>> instr delta =   -161497801    -7.2542%
>> time  delta =      -24.722 ms -6.5951%
>
> src/hotspot/share/classfile/systemDictionaryShared.cpp line 336:
> 
>> 334:
>> 335:   static unsigned int dumptime_hash(Symbol* sym)  {
>> 336:     if (sym == NULL) {
> 
> How about adding a comment "_invoked_name may be NULL"?

Comment added.

> src/hotspot/share/classfile/systemDictionaryShared.cpp line 2300:
> 
>> 2298:
>> 2299: class ArchivedLambdaMirrorPatcher {
>> 2300:   static void update(Klass* k) {
> 
> I think ArchivedLambdaMirrorPatcher can be subclass of ArchivedMirrorPatcher. That way you can share the same code for
> ArchivedMirrorPatcher::update (you can make this a protected method).

I've changed the ArchivedLambdaMirrorPatcher to the following:

class ArchivedLambdaMirrorPatcher : public ArchivedMirrorPatcher {
public:
  void do_value(const RunTimeLambdaProxyClassInfo* info) {
    InstanceKlass* ik = info->proxy_klass_head();
    while (ik != NULL) {
      update(ik);
      Klass* k = ik->next_link();
      ik = (k != NULL) ? InstanceKlass::cast(k) : NULL;
    }
  }
};

> src/hotspot/share/classfile/systemDictionaryShared.cpp line 2242:
> 
>> 2240:         st->print_cr("Dynamic Shared Lambda Dictionary");
>> 2241:         SharedLambdaDictionaryPrinter ldp(st);
>> 2242:         _dynamic_lambda_proxy_class_dictionary.iterate(&ldp);
> 
> I think this function can be refactored, something like:
> 
> SystemDictionaryShared::print_on(outputStream* st) {
>    if (UseSharedSpaces) {
>      print_on("", &_builtin_dictionary, &_unregistered_dictionary, &_lambda_proxy_class_dictionary);
>      if (DynamicArchive::is_mapped()) {
>        print_on("Dynamic ", &dynamic__builtin_dictionary, &_dynamic_unregistered_dictionary,
>          &_dynamic_lambda_proxy_class_dictionary);
>     }
>   }
> }

I've added the following print_on function for code refactoring:

void SystemDictionaryShared::print_on(const char* prefix,
                                      RunTimeSharedDictionary builtin_dictionary,
                                      RunTimeSharedDictionary unregistered_dictionary,
                                      LambdaProxyClassDictionary lambda_dictionary,
                                      outputStream* st) {
  st->print_cr("%sShared Dictionary", prefix);
  SharedDictionaryPrinter p(st);
  builtin_dictionary.iterate(&p);
  unregistered_dictionary.iterate(&p);
  if (!lambda_dictionary.empty()) {
    st->print_cr("%sShared Lambda Dictionary", prefix);
    SharedLambdaDictionaryPrinter ldp(st);
    lambda_dictionary.iterate(&ldp);
  }
}

> src/hotspot/share/classfile/systemDictionaryShared.cpp line 1984:
> 
>> 1982: int compare_runtime_lambda_proxy_class_info(const RunTimeLambdaProxyClassNode& r1,
>> 1983:                                             const RunTimeLambdaProxyClassNode& r2) {
>> 1984:   ResourceMark rm;
> 
> Is this function being used?

No, it is an unused function. I've removed it.

-------------

PR: https://git.openjdk.java.net/jdk/pull/364