--- old/src/hotspot/share/memory/heapShared.cpp	2020-07-26 22:10:06.325538521 -0700
+++ new/src/hotspot/share/memory/heapShared.cpp	2020-07-26 22:10:05.997526174 -0700
@@ -136,17 +136,21 @@
     return NULL;
   }
 
-  // Pre-compute object identity hash at CDS dump time.
-  obj->identity_hash();
-
   oop archived_oop = (oop)G1CollectedHeap::heap()->archive_mem_allocate(len);
   if (archived_oop != NULL) {
     Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), cast_from_oop<HeapWord*>(archived_oop), len);
     MetaspaceShared::relocate_klass_ptr(archived_oop);
-    // Clear age -- it might have been set if a GC happened during -Xshare:dump
-    markWord mark = archived_oop->mark_raw();
-    mark = mark.set_age(0);
-    archived_oop->set_mark_raw(mark);
+    // Reinitialize markword to remove age/marking/locking/etc.
+    //
+    // We need to retain the identity_hash, because it may have been used by some hashtables
+    // in the shared heap. This also has the side effect of pre-initializing the
+    // identity_hash for all shared objects, so they are less likely to be written
+    // into during run time, increasing the potential of memory sharing.
+    int hash_original = obj->identity_hash();
+    archived_oop->set_mark_raw(markWord::prototype().copy_set_hash(hash_original));
+    assert(archived_oop->mark().is_unlocked(), "sanity");
+    int hash_archived = archived_oop->identity_hash();
+    assert(hash_original == hash_archived, "Different hash codes: original %x, archived %x", hash_original, hash_archived);
     ArchivedObjectCache* cache = archived_object_cache();
     cache->put(obj, archived_oop);
     log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT,
--- old/test/hotspot/jtreg/runtime/cds/appcds/jvmti/dumpingWithAgent/SimpleAgent.java	2020-07-26 22:10:07.525583693 -0700
+++ new/test/hotspot/jtreg/runtime/cds/appcds/jvmti/dumpingWithAgent/SimpleAgent.java	2020-07-26 22:10:07.213571948 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,8 +23,29 @@
  */
 import java.lang.instrument.Instrumentation;
 
-public class SimpleAgent {
+public class SimpleAgent implements Runnable {
     public static void premain(String agentArg, Instrumentation instrumentation) {
         System.out.println("inside SimpleAgent");
+
+        Thread t = new Thread(new SimpleAgent());
+        t.setDaemon(true);
+        t.start();
+    }
+
+    // Test for JDK-8249276: make sure we can handle objects that are locked during
+    // -Xshare:dump
+    public void run() {
+        try {
+            while (true) {
+                System.out.println("Let's wait .....");
+                synchronized (Object.class) {
+                    Object.class.wait();
+                }
+                System.out.println("Huh?? notified??");
+            }
+        } catch (Throwable t) {
+            System.err.println("Unexpected: " + t);
+            throw new RuntimeException(t);
+        }
     }
 }