--- old/src/hotspot/share/runtime/globals.hpp	2020-01-31 16:35:14.103723047 -0500
+++ new/src/hotspot/share/runtime/globals.hpp	2020-01-31 16:35:13.747714373 -0500
@@ -698,6 +698,10 @@
   product(intx, MonitorBound, 0, "(Deprecated) Bound Monitor population")   \
           range(0, max_jint)                                                \
                                                                             \
+  develop(intx, StressMonitorInterferenceCount, 10,                         \
+          "Stress Monitor code paths")                                      \
+          range(0, 100)                                                     \
+                                                                            \
   experimental(intx, MonitorUsedDeflationThreshold, 90,                     \
                 "Percentage of used monitors before triggering cleanup "    \
                 "safepoint which deflates monitors (0 is off). "            \
--- old/src/hotspot/share/runtime/synchronizer.cpp	2020-01-31 16:35:14.599735132 -0500
+++ new/src/hotspot/share/runtime/synchronizer.cpp	2020-01-31 16:35:14.255726750 -0500
@@ -1293,7 +1293,7 @@
     m = take_from_start_of_om_free_list(self);
     if (m != NULL) {
       guarantee(m->object() == NULL, "invariant");
-      prepend_to_om_in_use_list(self, m);
+      // prepend_to_om_in_use_list(self, m);
       return m;
     }
 
@@ -1394,7 +1394,7 @@
             m->_recursions);
   // _next_om is used for both per-thread in-use and free lists so
   // we have to remove 'm' from the in-use list first (as needed).
-  if (from_per_thread_alloc) {
+  if (false && from_per_thread_alloc) {
     // Need to remove 'm' from om_in_use_list.
     ObjectMonitor* mid = NULL;
     ObjectMonitor* next = NULL;
@@ -1620,6 +1620,7 @@
          !SafepointSynchronize::is_at_safepoint(), "invariant");
 
   EventJavaMonitorInflate event;
+  int interference_count = 0;
 
   for (;;) {
     const markWord mark = object->mark();
@@ -1683,11 +1684,13 @@
       m->_Responsible  = NULL;
       m->_SpinDuration = ObjectMonitor::Knob_SpinLimit;   // Consider: maintain by type/class
 
-      markWord cmp = object->cas_set_mark(markWord::INFLATING(), mark);
-      if (cmp != mark) {
+      interference_count++;
+      if (StressMonitorInterferenceCount > interference_count
+          || object->cas_set_mark(markWord::INFLATING(), mark) != mark) {
         om_release(self, m, true);
         continue;       // Interference -- just retry
       }
+      prepend_to_om_in_use_list(self, m);
 
       // We've successfully installed INFLATING (0) into the mark-word.
       // This is the only case where 0 will appear in a mark-word.
@@ -1776,7 +1779,8 @@
     m->_Responsible  = NULL;
     m->_SpinDuration = ObjectMonitor::Knob_SpinLimit;       // consider: keep metastats by type/class
 
-    if (object->cas_set_mark(markWord::encode(m), mark) != mark) {
+    interference_count++;
+    if (StressMonitorInterferenceCount > interference_count || object->cas_set_mark(markWord::encode(m), mark) != mark) {
       m->set_header(markWord::zero());
       m->set_object(NULL);
       m->Recycle();
@@ -1787,6 +1791,7 @@
       // The state-transitions are one-way, so there's no chance of
       // live-lock -- "Inflated" is an absorbing state.
     }
+    prepend_to_om_in_use_list(self, m);
 
     // Hopefully the performance counters are allocated on distinct
     // cache lines to avoid false sharing on MP systems ...