--- old/src/share/vm/runtime/globals.hpp	2020-01-27 23:21:00.000000000 -0800
+++ new/src/share/vm/runtime/globals.hpp	2020-01-27 23:21:00.000000000 -0800
@@ -3991,6 +3991,24 @@
   product(bool, UseLockedTracing, false,                                    \
           "Use locked-tracing when doing event-based tracing")              \
                                                                             \
+  notproduct(intx, DelayInGCLogging, 0,                                     \
+          "Delay milliseconds to simulate IO blocking for GC log testing")  \
+                                                                            \
+  product(bool, AsyncGCLogging, true,                                       \
+          "Enble asynchronous GC logging")                                  \
+                                                                            \
+  product(intx, GCLogBufferSize, 500,                                       \
+          "Entries of ringbuffer for GC log writing")                       \
+                                                                            \
+  product(intx, GCLogFlushInterval, 200,                                    \
+          "Milliseconds between GC log flushings")                          \
+                                                                            \
+  product(bool, PrintGCLogFlushTime, false,                                 \
+          "Print the time for GC log flushings in seconds")                 \
+                                                                            \
+  diagnostic(bool, PrintGCLogStatistics, false,                             \
+          "Print statistics of dismissed GC log")                           \
+                                                                            \
   product_pd(bool, PreserveFramePointer,                                    \
              "Use the FP register for holding the frame pointer "           \
              "and not as a general purpose register.")