--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/tools/HeapSummary.java	2018-06-08 19:45:41.831056130 +0200
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/tools/HeapSummary.java	2018-06-08 19:45:41.563044502 +0200
@@ -29,6 +29,7 @@
 import sun.jvm.hotspot.gc.parallel.*;
 import sun.jvm.hotspot.gc.serial.*;
 import sun.jvm.hotspot.gc.shared.*;
+import sun.jvm.hotspot.gc.z.*;
 import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.memory.*;
 import sun.jvm.hotspot.oops.*;
@@ -124,6 +125,9 @@
          printValMB("used     = ", oldGen.used());
          printValMB("free     = ", oldFree);
          System.out.println(alignment + (double)oldGen.used() * 100.0 / oldGen.capacity() + "% used");
+      } else if (heap instanceof ZCollectedHeap) {
+         ZCollectedHeap zheap = (ZCollectedHeap) heap;
+         zheap.printOn(System.out);
       } else {
          throw new RuntimeException("unknown CollectedHeap type : " + heap.getClass());
       }
@@ -159,6 +163,14 @@
            l = getFlagValue("ParallelGCThreads", flagMap);
            System.out.println("with " + l + " thread(s)");
            return;
+       }
+
+       l = getFlagValue("UseZGC", flagMap);
+       if (l == 1L) {
+           System.out.print("ZGC ");
+           l = getFlagValue("ParallelGCThreads", flagMap);
+           System.out.println("with " + l + " thread(s)");
+           return;
        }
 
        System.out.println("Mark Sweep Compact GC");