Summary

The RegisterFinalizersAtInit option controls whether finalizers are registered after allocation or at return from the Object. constructor. The default is to register at the end of Object. and this has been the default for years.

Problem

Continuing to support the flag is counter to the increased Integrity push [0] and will be increasingly problematic when Project Valhalla merges in due to allowing larval objects to escape before they are frozen.

[0] https://openjdk.org/jeps/8305968

Solution

Deprecate the option in JDK22, obsolete in JDK23, and expire in JDK24.

Specification

diff --git a/src/hotspot/share/runtime/arguments.cpp b/src/hotspot/share/runtime/arguments.cpp
index dc1e15121b28..f6c1b0003e83 100644
--- a/src/hotspot/share/runtime/arguments.cpp
+++ b/src/hotspot/share/runtime/arguments.cpp
@@ -509,6 +509,7 @@ static SpecialFlag const special_jvm_flags[] = {
   { "DynamicDumpSharedSpaces",      JDK_Version::jdk(18), JDK_Version::jdk(19), JDK_Version::undefined() },
   { "RequireSharedSpaces",          JDK_Version::jdk(18), JDK_Version::jdk(19), JDK_Version::undefined() },
   { "UseSharedSpaces",              JDK_Version::jdk(18), JDK_Version::jdk(19), JDK_Version::undefined() },
+  { "RegisterFinalizersAtInit",     JDK_Version::jdk(22), JDK_Version::jdk(23), JDK_Version::jdk(24) },

   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
   { "DefaultMaxRAMFraction",        JDK_Version::jdk(8),  JDK_Version::undefined(), JDK_Version::undefined() },
diff --git a/src/hotspot/share/runtime/globals.hpp b/src/hotspot/share/runtime/globals.hpp
index 4ae156a773ea..f3c1ceab3d7f 100644
--- a/src/hotspot/share/runtime/globals.hpp
+++ b/src/hotspot/share/runtime/globals.hpp
@@ -667,8 +667,8 @@ const int ObjectAlignmentInBytes = 8;
           "Print JVM warnings to output stream")                            \
                                                                             \
   product(bool, RegisterFinalizersAtInit, true,                             \
-          "Register finalizable objects at end of Object.<init> or "        \
-          "after allocation")                                               \
+          "(Deprecated) Register finalizable objects at end of "            \
+          "Object.<init> or after allocation")                              \
                                                                             \
   develop(bool, RegisterReferences, true,                                   \
           "Tell whether the VM should register soft/weak/final/phantom "    \