8359924: Deprecate and obsolete ParallelRefProcEnabled

src/hotspot/share/gc/shared/gc_globals.hpp

@@ -199,7 +199,8 @@
           range(1, (INT_MAX - 1))                                           \
                                                                             \
   product(bool, ParallelRefProcEnabled, false,                              \
-          "Enable parallel reference processing whenever possible")         \
+          "(Deprecated) Enable parallel reference processing "              \
+          "whenever possible")                                              \
                                                                             \
   product(bool, ParallelRefProcBalancingEnabled, true,                      \
           "Enable balancing of reference processing queues")                \

src/hotspot/share/runtime/arguments.cpp

@@ -532,6 +532,7 @@ static SpecialFlag const special_jvm_flags[] = {
 #ifdef _LP64
   { "UseCompressedClassPointers",   JDK_Version::jdk(25),  JDK_Version::jdk(26), JDK_Version::undefined() },
 #endif
+  { "ParallelRefProcEnabled",       JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
   { "CreateMinidumpOnCrash",        JDK_Version::jdk(9),  JDK_Version::undefined(), JDK_Version::undefined() },
 

src/java.base/share/man/java.md

@@ -2701,14 +2701,6 @@ Java HotSpot VM.
 
     >   `-XX:ParallelGCThreads=2`
 
-`-XX:+ParallelRefProcEnabled`
-:   Enables parallel reference processing. By default, collectors employing multiple
-    threads perform parallel reference processing if the number of parallel threads
-    to use is larger than one.
-    The option is available only when the throughput or G1 garbage collector is used
-    (`-XX:+UseParallelGC` or `-XX:+UseG1GC`). Other collectors employing multiple
-    threads always perform reference processing in parallel.
-
 `-XX:+PrintAdaptiveSizePolicy`
 :   Enables printing of information about adaptive-generation sizing. By
     default, this option is disabled.
@@ -2904,6 +2896,14 @@ they're used.
 :   Enables the use of Java Flight Recorder (JFR) during the runtime of the
     application. Since JDK 8u40 this option has not been required to use JFR.
 
+`-XX:+ParallelRefProcEnabled`
+:   Enables parallel reference processing. By default, collectors employing multiple
+    threads perform parallel reference processing if the number of parallel threads
+    to use is larger than one.
+    The option is available only when the throughput or G1 garbage collector is used
+    (`-XX:+UseParallelGC` or `-XX:+UseG1GC`). Other collectors employing multiple
+    threads always perform reference processing in parallel.
+
 ## Obsolete Java Options
 
 These `java` options are still accepted but ignored, and a warning is issued