8234531: Remove CMS code from CLDG and safepoint cleanup

Reviewed-by: coleenp, zgu

src/hotspot/share/classfile/classLoaderDataGraph.cpp

@@ -186,10 +186,7 @@ void ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces() {
 // GC root of class loader data created.
 ClassLoaderData* volatile ClassLoaderDataGraph::_head = NULL;
 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
-ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
-ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
 
-bool ClassLoaderDataGraph::_should_purge = false;
 bool ClassLoaderDataGraph::_should_clean_deallocate_lists = false;
 bool ClassLoaderDataGraph::_safepoint_cleanup_needed = false;
 bool ClassLoaderDataGraph::_metaspace_oom = false;
@@ -249,9 +246,7 @@ ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_unsafe_anonymo
 
 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
   assert_locked_or_safepoint_weak(ClassLoaderDataGraph_lock);
-  // Only walk the head until any clds not purged from prior unloading
+  for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
-  // (CMS doesn't purge right away).
-  for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
     assert(cld->is_unloading(), "invariant");
     cl->do_cld(cld);
   }
@@ -381,9 +376,7 @@ void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
 
 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-  // Only walk the head until any clds not purged from prior unloading
+  for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
-  // (CMS doesn't purge right away).
-  for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
     assert(cld->is_unloading(), "invariant");
     cld->modules_do(f);
   }
@@ -399,9 +392,7 @@ void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
 
 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-  // Only walk the head until any clds not purged from prior unloading
+  for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
-  // (CMS doesn't purge right away).
-  for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
     assert(cld->is_unloading(), "invariant");
     cld->packages_do(f);
   }
@@ -424,9 +415,7 @@ void ClassLoaderDataGraph::unlocked_loaded_classes_do(KlassClosure* klass_closur
 
 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-  // Only walk the head until any clds not purged from prior unloading
+  for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
-  // (CMS doesn't purge right away).
-  for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
     assert(cld->is_unloading(), "invariant");
     cld->classes_do(f);
   }
@@ -476,32 +465,6 @@ void ClassLoaderDataGraph::print_table_statistics(outputStream* st) {
   }
 }
 
-GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
-  assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
-  assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
-
-  GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
-
-  // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
-  ClassLoaderData* curr = _head;
-  while (curr != _saved_head) {
-    if (!curr->claimed(ClassLoaderData::_claim_strong)) {
-      array->push(curr);
-      LogTarget(Debug, class, loader, data) lt;
-      if (lt.is_enabled()) {
-        LogStream ls(lt);
-        ls.print("found new CLD: ");
-        curr->print_value_on(&ls);
-        ls.cr();
-      }
-    }
-
-    curr = curr->_next;
-  }
-
-  return array;
-}
-
 #ifndef PRODUCT
 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
   assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
@@ -544,10 +507,6 @@ bool ClassLoaderDataGraph::do_unloading() {
   uint loaders_processed = 0;
   uint loaders_removed = 0;
 
-  // Save previous _unloading pointer for CMS which may add to unloading list before
-  // purging and we don't want to rewalk the previously unloaded class loader data.
-  _saved_unloading = _unloading;
-
   data = _head;
   while (data != NULL) {
     if (data->is_alive()) {

src/hotspot/share/classfile/classLoaderDataGraph.hpp

@@ -43,10 +43,6 @@ class ClassLoaderDataGraph : public AllStatic {
   // All CLDs (except the null CLD) can be reached by walking _head->_next->...
   static ClassLoaderData* volatile _head;
   static ClassLoaderData* _unloading;
-  // CMS support.
-  static ClassLoaderData* _saved_head;
-  static ClassLoaderData* _saved_unloading;
-  static bool _should_purge;
 
   // Set if there's anything to purge in the deallocate lists or previous versions
   // during a safepoint after class unloading in a full GC.
@@ -115,18 +111,6 @@ class ClassLoaderDataGraph : public AllStatic {
   static void print_dictionary(outputStream* st);
   static void print_table_statistics(outputStream* st);
 
-  // CMS support.
-  static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }
-  static GrowableArray<ClassLoaderData*>* new_clds();
-
-  static void set_should_purge(bool b) { _should_purge = b; }
-  static bool should_purge_and_reset() {
-    bool res = _should_purge;
-    // reset for next time.
-    set_should_purge(false);
-    return res;
-  }
-
   static int resize_dictionaries();
 
   static bool has_metaspace_oom()           { return _metaspace_oom; }

src/hotspot/share/runtime/safepoint.cpp

@@ -620,19 +620,6 @@ public:
       }
     }
 
-    if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) {
-      if (ClassLoaderDataGraph::should_purge_and_reset()) {
-        // CMS delays purging the CLDG until the beginning of the next safepoint and to
-        // make sure concurrent sweep is done
-        const char* name = "purging class loader data graph";
-        EventSafepointCleanupTask event;
-        TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup));
-        ClassLoaderDataGraph::purge();
-
-        post_safepoint_cleanup_task_event(event, safepoint_id, name);
-      }
-    }
-
     if (_subtasks.try_claim_task(SafepointSynchronize::SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE)) {
       if (Dictionary::does_any_dictionary_needs_resizing()) {
         const char* name = "resizing system dictionaries";

src/hotspot/share/runtime/safepoint.hpp

@@ -75,7 +75,6 @@ class SafepointSynchronize : AllStatic {
     SAFEPOINT_CLEANUP_COMPILATION_POLICY,
     SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH,
     SAFEPOINT_CLEANUP_STRING_TABLE_REHASH,
-    SAFEPOINT_CLEANUP_CLD_PURGE,
     SAFEPOINT_CLEANUP_SYSTEM_DICTIONARY_RESIZE,
     SAFEPOINT_CLEANUP_REQUEST_OOPSTORAGE_CLEANUP,
     // Leave this one last.