--- old/src/hotspot/share/gc/z/zHeap.cpp	2019-07-26 14:17:43.948820090 +0200
+++ new/src/hotspot/share/gc/z/zHeap.cpp	2019-07-26 14:17:43.678811210 +0200
@@ -25,6 +25,7 @@
 #include "gc/shared/gcArguments.hpp"
 #include "gc/shared/oopStorage.hpp"
 #include "gc/z/zAddress.hpp"
+#include "gc/z/zArray.inline.hpp"
 #include "gc/z/zGlobals.hpp"
 #include "gc/z/zHeap.inline.hpp"
 #include "gc/z/zHeapIterator.hpp"
@@ -386,6 +387,22 @@
   _reference_processor.enqueue_references();
 }
 
+class ZHeapReclaimPagesTask : public ZTask {
+private:
+  ZArrayParallelIterator<ZPage*> _iter;
+
+public:
+  ZHeapReclaimPagesTask(ZArray<ZPage*>* pages) :
+      ZTask("ZHeapReclaimPagesTask"),
+      _iter(pages) {}
+
+  virtual void work() {
+    for (ZPage* page; _iter.next(&page);) {
+      ZHeap::heap()->free_page(page, true /* reclaimed */);
+    }
+  }
+};
+
 void ZHeap::select_relocation_set() {
   // Do not allow pages to be deleted
   _page_allocator.enable_deferred_delete();
@@ -403,17 +420,18 @@
       // Register live page
       selector.register_live_page(page);
     } else {
-      // Register garbage page
-      selector.register_garbage_page(page);
-
-      // Reclaim page immediately
-      free_page(page, true /* reclaimed */);
+      // Register reclaimable page
+      selector.register_reclaimable_page(page);
     }
   }
 
   // Allow pages to be deleted
   _page_allocator.disable_deferred_delete();
 
+  // Free reclaimable page
+  ZHeapReclaimPagesTask task(selector.reclaimable());
+  _workers.run_concurrent(&task);
+
   // Select pages to relocate
   selector.select(&_relocation_set);
 
--- old/src/hotspot/share/gc/z/zRelocationSetSelector.cpp	2019-07-26 14:17:44.358833575 +0200
+++ new/src/hotspot/share/gc/z/zRelocationSetSelector.cpp	2019-07-26 14:17:44.065823938 +0200
@@ -169,6 +169,7 @@
 ZRelocationSetSelector::ZRelocationSetSelector() :
     _small("Small", ZPageSizeSmall, ZObjectSizeLimitSmall),
     _medium("Medium", ZPageSizeMedium, ZObjectSizeLimitMedium),
+    _reclaimable(),
     _live(0),
     _garbage(0),
     _fragmentation(0) {}
@@ -190,10 +191,15 @@
   _garbage += garbage;
 }
 
-void ZRelocationSetSelector::register_garbage_page(ZPage* page) {
+void ZRelocationSetSelector::register_reclaimable_page(ZPage* page) {
+  _reclaimable.add(page);
   _garbage += page->size();
 }
 
+ZArray<ZPage*>* ZRelocationSetSelector::reclaimable() {
+  return &_reclaimable;
+}
+
 void ZRelocationSetSelector::select(ZRelocationSet* relocation_set) {
   // Select pages to relocate. The resulting relocation set will be
   // sorted such that medium pages comes first, followed by small
--- old/src/hotspot/share/gc/z/zRelocationSetSelector.hpp	2019-07-26 14:17:44.705844988 +0200
+++ new/src/hotspot/share/gc/z/zRelocationSetSelector.hpp	2019-07-26 14:17:44.471837292 +0200
@@ -64,6 +64,7 @@
 private:
   ZRelocationSetSelectorGroup _small;
   ZRelocationSetSelectorGroup _medium;
+  ZArray<ZPage*>              _reclaimable;
   size_t                      _live;
   size_t                      _garbage;
   size_t                      _fragmentation;
@@ -72,7 +73,9 @@
   ZRelocationSetSelector();
 
   void register_live_page(ZPage* page);
-  void register_garbage_page(ZPage* page);
+  void register_reclaimable_page(ZPage* page);
+
+  ZArray<ZPage*>* reclaimable();
   void select(ZRelocationSet* relocation_set);
 
   size_t live() const;