src/hotspot/share/memory/metaspaceShared.cpp

@@ -34,10 +34,11 @@
 #include "classfile/symbolTable.hpp"
 #include "classfile/stringTable.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/systemDictionaryShared.hpp"
 #include "code/codeCache.hpp"
+#include "gc/shared/gcLocker.hpp"
 #include "gc/shared/softRefPolicy.hpp"
 #include "interpreter/bytecodeStream.hpp"
 #include "interpreter/bytecodes.hpp"
 #include "logging/log.hpp"
 #include "logging/logMessage.hpp"

@@ -1227,10 +1228,11 @@
   void print_region_stats(FileMapInfo* map_info);
   void print_bitmap_region_stats(size_t size, size_t total_size);
   void print_heap_region_stats(GrowableArray<MemRegion> *heap_mem,
                                const char *name, size_t total_size);
   void relocate_to_requested_base_address(CHeapBitMap* ptrmap);
+  void run_gc();
 
 public:
 
   VMOp_Type type() const { return VMOp_PopulateDumpSharedSpace; }
   void doit();   // outline because gdb sucks

@@ -1634,11 +1636,30 @@
     ptrmap->iterate(&patcher);
     ArchivePtrMarker::compact(patcher.max_non_null_offset());
   }
 }
 
+void VM_PopulateDumpSharedSpace::run_gc() {
+  if (HeapShared::is_heap_object_archiving_allowed()) {
+    // Avoid fragmentation while archiving heap objects.
+    // We do this inside a safepoint, so that no further allocation can happen after GC
+    // has finished.
+    if (GCLocker::is_active()) {
+      // This should not happen during -Xshare:dump. If you see this, probably the Java core lib
+      // has been modified such that JNI code is executed in some clean up threads after
+      // we have finished class loading.
+      log_warning(cds)("GC locker is held; GC is skipped. This may produce suboptimal archive heap regions.");
+    } else {
+      log_info(cds)("Run GC ...");
+      Universe::heap()->collect_as_vm_thread(GCCause::_archive_time_gc);
+      log_info(cds)("Run GC done");
+    }
+  }
+}
+
 void VM_PopulateDumpSharedSpace::doit() {
+  run_gc();
   CHeapBitMap ptrmap;
   MetaspaceShared::initialize_ptr_marker(&ptrmap);
 
   // We should no longer allocate anything from the metaspace, so that:
   //

@@ -1953,18 +1974,13 @@
     // fails verification, all other interfaces that were not specified in the classlist but
     // are implemented by K are not verified.
     link_and_cleanup_shared_classes(CATCH);
     log_info(cds)("Rewriting and linking classes: done");
 
-    if (HeapShared::is_heap_object_archiving_allowed()) {
-      // Avoid fragmentation while archiving heap objects.
-      Universe::heap()->soft_ref_policy()->set_should_clear_all_soft_refs(true);
-      Universe::heap()->collect(GCCause::_archive_time_gc);
-      Universe::heap()->soft_ref_policy()->set_should_clear_all_soft_refs(false);
-    }
-
     VM_PopulateDumpSharedSpace op;
+    MutexLocker ml(THREAD, HeapShared::is_heap_object_archiving_allowed() ?
+                   Heap_lock : NULL);     // needed for collect_as_vm_thread
     VMThread::execute(&op);
   }
 }