diff a/src/hotspot/share/gc/shenandoah/shenandoahYoungGeneration.cpp b/src/hotspot/share/gc/shenandoah/shenandoahYoungGeneration.cpp
--- /dev/null
+++ b/src/hotspot/share/gc/shenandoah/shenandoahYoungGeneration.cpp
@@ -0,0 +1,105 @@
+/*
+ * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+#include "precompiled.hpp"
+
+#include "gc/shenandoah/shenandoahFreeSet.hpp"
+#include "gc/shenandoah/shenandoahHeap.hpp"
+#include "gc/shenandoah/shenandoahHeapRegionClosures.hpp"
+#include "gc/shenandoah/shenandoahUtils.hpp"
+#include "gc/shenandoah/shenandoahYoungGeneration.hpp"
+#include "gc/shenandoah/heuristics/shenandoahYoungHeuristics.hpp"
+
+ShenandoahYoungGeneration::ShenandoahYoungGeneration(uint max_queues, size_t max_capacity, size_t soft_max_capacity) :
+  ShenandoahGeneration(YOUNG, max_queues, max_capacity, soft_max_capacity),
+  _old_gen_task_queues(nullptr) {
+}
+
+void ShenandoahYoungGeneration::set_concurrent_mark_in_progress(bool in_progress) {
+  ShenandoahHeap* heap = ShenandoahHeap::heap();
+  heap->set_concurrent_young_mark_in_progress(in_progress);
+  if (is_bootstrap_cycle() && in_progress && !heap->is_prepare_for_old_mark_in_progress()) {
+    // This is not a bug. When the bootstrapping marking phase is complete,
+    // the old generation marking is still in progress, unless it's not.
+    // In the case that old-gen preparation for mixed evacuation has been
+    // preempted, we do not want to set concurrent old mark to be in progress.
+    heap->set_concurrent_old_mark_in_progress(in_progress);
+  }
+}
+
+bool ShenandoahYoungGeneration::contains(ShenandoahHeapRegion* region) const {
+  // TODO: why not test for equals YOUNG_GENERATION?  As written, returns true for regions that are FREE
+  return !region->is_old();
+}
+
+void ShenandoahYoungGeneration::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* cl) {
+  // Just iterate over the young generation here.
+  ShenandoahIncludeRegionClosure<YOUNG_GENERATION> young_regions_cl(cl);
+  ShenandoahHeap::heap()->parallel_heap_region_iterate(&young_regions_cl);
+}
+
+void ShenandoahYoungGeneration::heap_region_iterate(ShenandoahHeapRegionClosure* cl) {
+  ShenandoahIncludeRegionClosure<YOUNG_GENERATION> young_regions_cl(cl);
+  ShenandoahHeap::heap()->heap_region_iterate(&young_regions_cl);
+}
+
+void ShenandoahYoungGeneration::parallel_region_iterate_free(ShenandoahHeapRegionClosure* cl) {
+  ShenandoahExcludeRegionClosure<OLD_GENERATION> exclude_cl(cl);
+  ShenandoahHeap::heap()->parallel_heap_region_iterate(&exclude_cl);
+}
+
+bool ShenandoahYoungGeneration::is_concurrent_mark_in_progress() {
+  return ShenandoahHeap::heap()->is_concurrent_young_mark_in_progress();
+}
+
+void ShenandoahYoungGeneration::reserve_task_queues(uint workers) {
+  ShenandoahGeneration::reserve_task_queues(workers);
+  if (is_bootstrap_cycle()) {
+    _old_gen_task_queues->reserve(workers);
+  }
+}
+
+bool ShenandoahYoungGeneration::contains(oop obj) const {
+  return ShenandoahHeap::heap()->is_in_young(obj);
+}
+
+ShenandoahHeuristics* ShenandoahYoungGeneration::initialize_heuristics(ShenandoahMode* gc_mode) {
+  _young_heuristics = new ShenandoahYoungHeuristics(this);
+  _heuristics = _young_heuristics;
+  _heuristics->set_guaranteed_gc_interval(ShenandoahGuaranteedYoungGCInterval);
+  confirm_heuristics_mode();
+  return _heuristics;
+}
+
+size_t ShenandoahYoungGeneration::available() const {
+  // The collector reserve may eat into what the mutator is allowed to use. Make sure we are looking
+  // at what is available to the mutator when reporting how much memory is available.
+  size_t available = this->ShenandoahGeneration::available();
+  return MIN2(available, ShenandoahHeap::heap()->free_set()->available());
+}
+
+size_t ShenandoahYoungGeneration::soft_available() const {
+  size_t available = this->ShenandoahGeneration::soft_available();
+  return MIN2(available, ShenandoahHeap::heap()->free_set()->available());
+}
+
