diff -r 1256c8d923e8 -r e0fd97beab7e src/hotspot/share/memory/metaspace.cpp
--- a/src/hotspot/share/memory/metaspace.cpp	Fri Nov 09 12:08:53 2018 +0800
+++ b/src/hotspot/share/memory/metaspace.cpp	Thu Nov 01 10:59:05 2018 -0700
@@ -1260,6 +1260,8 @@
 MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
                               MetaspaceObj::Type type, TRAPS) {
   assert(!_frozen, "sanity");
+  assert(!(DumpSharedSpaces && THREAD->is_VM_thread()), "sanity");
+
   if (HAS_PENDING_EXCEPTION) {
     assert(false, "Should not allocate with exception pending");
     return NULL;  // caller does a CHECK_NULL too
@@ -1277,12 +1279,10 @@
     tracer()->report_metaspace_allocation_failure(loader_data, word_size, type, mdtype);
 
     // Allocation failed.
-    if (is_init_completed() && !(DumpSharedSpaces && THREAD->is_VM_thread())) {
+    if (is_init_completed()) {
       // Only start a GC if the bootstrapping has completed.
-      // Also, we cannot GC if we are at the end of the CDS dumping stage which runs inside
-      // the VM thread.
-
-      // Try to clean out some memory and retry.
+      // Try to clean out some heap memory and retry. This can prevent premature
+      // expansion of the metaspace.
       result = Universe::heap()->satisfy_failed_metadata_allocation(loader_data, word_size, mdtype);
     }
   }
@@ -1408,6 +1408,7 @@
 }
 
 ClassLoaderMetaspace::~ClassLoaderMetaspace() {
+  Metaspace::assert_not_frozen();
   DEBUG_ONLY(Atomic::inc(&g_internal_statistics.num_metaspace_deaths));
   delete _vsm;
   if (Metaspace::using_class_space()) {