RFR: 8367475: Incorrect lock usage in LambdaFormInvokers::regenerate_holder_classes

[Ioi Lam]

The assert happens because we attempt to allocate Java objects while holding a mutex:


    MutexLocker ml(Thread::current(), LambdaFormInvokers_lock);
    list_lines = oopFactory::new_objArray_handle(vmClasses::String_klass(), len, CHECK);
    for (int i = 0; i < len; i++) {
      Handle h_line = java_lang_String::create_from_str(_lambdaform_lines->at(i), CHECK);


It's possible for the allocations to trigger a call to Java when JVMTI is enabled.

The fix is to do the allocation outside of the mutex. However, we still use the mutex to make sure we have a consistent view of `_lambdaform_lines`, which may be modified by concurrent Java threads.

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Commit messages:
 - @liach comment -- assert only dumper thread can call LambdaFormInvokers::regenerate_holder_classes()
 - 8360269: Incorrect lock usage in LambdaFormInvokers::regenerate_holder_classes

Changes: https://git.openjdk.org/jdk/pull/27231/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27231&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367475
  Stats: 40 lines in 3 files changed: 24 ins; 8 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/27231.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27231/head:pull/27231

PR: https://git.openjdk.org/jdk/pull/27231