8005602: NPG: classunloading does not happen while CMS GC with...

8005602: NPG: classunloading does not happen while CMS GC with -XX:+CMSClassUnloadingEnabled is used
Summary: Call purge() on CLDG after sweep(), reorder purge() call in GenCollectedHeap
Reviewed-by: jmasa, stefank

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp

@@ -6068,6 +6068,10 @@ void CMSCollector::sweep(bool asynch) {
   verify_work_stacks_empty();
   verify_overflow_empty();
 
+  if (should_unload_classes()) {
+    ClassLoaderDataGraph::purge();
+  }
+
   _intra_sweep_timer.stop();
   _intra_sweep_estimate.sample(_intra_sweep_timer.seconds());
 

src/share/vm/memory/genCollectedHeap.cpp

@@ -554,6 +554,8 @@ void GenCollectedHeap::do_collection(bool  full,
     }
 
     if (complete) {
+      // Delete metaspaces for unloaded class loaders and clean up loader_data graph
+      ClassLoaderDataGraph::purge();
       // Resize the metaspace capacity after full collections
       MetaspaceGC::compute_new_size();
       update_full_collections_completed();
@@ -564,11 +566,6 @@ void GenCollectedHeap::do_collection(bool  full,
 
     gc_epilogue(complete);
 
-    // Delete metaspaces for unloaded class loaders and clean up loader_data graph
-    if (complete) {
-      ClassLoaderDataGraph::purge();
-    }
-
     if (must_restore_marks_for_biased_locking) {
       BiasedLocking::restore_marks();
     }

src/share/vm/memory/metaspace.cpp

@@ -1309,8 +1309,7 @@ void MetaspaceGC::compute_new_size() {
       gclog_or_tty->print_cr("  metaspace HWM: %.1fK", new_capacity_until_GC / (double) K);
     }
   }
-  assert(vsl->used_bytes_sum() == used_after_gc &&
-         used_after_gc <= vsl->capacity_bytes_sum(),
+  assert(used_after_gc <= vsl->capacity_bytes_sum(),
          "sanity check");
 
 }
@@ -1970,6 +1969,9 @@ void SpaceManager::initialize() {
 }
 
 SpaceManager::~SpaceManager() {
+  // This call this->_lock which can't be done while holding expand_lock()
+  const size_t in_use_before = sum_capacity_in_chunks_in_use();
+
   MutexLockerEx fcl(SpaceManager::expand_lock(),
                     Mutex::_no_safepoint_check_flag);
 
@@ -1987,7 +1989,7 @@ SpaceManager::~SpaceManager() {
 
   // Have to update before the chunks_in_use lists are emptied
   // below.
-  chunk_manager->inc_free_chunks_total(sum_capacity_in_chunks_in_use(),
+  chunk_manager->inc_free_chunks_total(in_use_before,
                                        sum_count_in_chunks_in_use());
 
   // Add all the chunks in use by this space manager