--- old/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2017-10-17 22:53:42.156221434 +0200
+++ new/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2017-10-17 22:53:41.912213546 +0200
@@ -48,6 +48,7 @@
 #include "gc/shared/strongRootsScope.hpp"
 #include "gc/shared/taskqueue.inline.hpp"
 #include "gc/shared/vmGCOperations.hpp"
+#include "gc/shared/weakProcessor.hpp"
 #include "logging/log.hpp"
 #include "memory/allocation.hpp"
 #include "memory/resourceArea.hpp"
@@ -1603,6 +1604,23 @@
   // Is alive closure.
   G1CMIsAliveClosure g1_is_alive(g1h);
 
+  // Instances of the 'Keep Alive' and 'Complete GC' closures used
+  // in serial reference processing. Note these closures are also
+  // used for serially processing (by the the current thread) the
+  // JNI references during parallel reference processing.
+  //
+  // These closures do not need to synchronize with the worker
+  // threads involved in parallel reference processing as these
+  // instances are executed serially by the current thread (e.g.
+  // reference processing is not multi-threaded and is thus
+  // performed by the current thread instead of a gang worker).
+  //
+  // The gang tasks involved in parallel reference processing create
+  // their own instances of these closures, which do their own
+  // synchronization among themselves.
+  G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
+  G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
+
   // Inner scope to exclude the cleaning of the string and symbol
   // tables from the displayed time.
   {
@@ -1617,23 +1635,6 @@
     rp->setup_policy(clear_all_soft_refs);
     assert(_global_mark_stack.is_empty(), "mark stack should be empty");
 
-    // Instances of the 'Keep Alive' and 'Complete GC' closures used
-    // in serial reference processing. Note these closures are also
-    // used for serially processing (by the the current thread) the
-    // JNI references during parallel reference processing.
-    //
-    // These closures do not need to synchronize with the worker
-    // threads involved in parallel reference processing as these
-    // instances are executed serially by the current thread (e.g.
-    // reference processing is not multi-threaded and is thus
-    // performed by the current thread instead of a gang worker).
-    //
-    // The gang tasks involved in parallel reference processing create
-    // their own instances of these closures, which do their own
-    // synchronization among themselves.
-    G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
-    G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
-
     // We need at least one active thread. If reference processing
     // is not multi-threaded we use the current (VMThread) thread,
     // otherwise we use the work gang from the G1CollectedHeap and
@@ -1687,6 +1688,11 @@
     assert(!rp->discovery_enabled(), "Post condition");
   }
 
+  {
+    GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
+    WeakProcessor::weak_oops_do(&g1_is_alive, &g1_keep_alive, &g1_drain_mark_stack);
+  }
+
   if (has_overflown()) {
     // We can not trust g1_is_alive if the marking stack overflowed
     return;