--- old/src/hotspot/share/runtime/serviceThread.cpp	2020-02-03 17:39:31.000000000 -0500
+++ new/src/hotspot/share/runtime/serviceThread.cpp	2020-02-03 17:39:30.000000000 -0500
@@ -110,6 +110,7 @@
     bool thread_id_table_work = false;
     bool protection_domain_table_work = false;
     bool oopstorage_work = false;
+    bool deflate_idle_monitors = false;
     JvmtiDeferredEvent jvmti_event;
     {
       // Need state transition ThreadBlockInVM so that this thread
@@ -136,10 +137,14 @@
               (resolved_method_table_work = ResolvedMethodTable::has_work()) |
               (thread_id_table_work = ThreadIdTable::has_work()) |
               (protection_domain_table_work = SystemDictionary::pd_cache_table()->has_work()) |
-              (oopstorage_work = OopStorage::has_cleanup_work_and_reset())
+              (oopstorage_work = OopStorage::has_cleanup_work_and_reset()) |
+              (deflate_idle_monitors = ObjectSynchronizer::is_async_deflation_needed())
              ) == 0) {
         // Wait until notified that there is some work to do.
-        ml.wait();
+        // If AsyncDeflateIdleMonitors, then we wait for
+        // GuaranteedSafepointInterval so that is_async_deflation_needed()
+        // is checked at the same interval.
+        ml.wait(AsyncDeflateIdleMonitors ? GuaranteedSafepointInterval : 0);
       }
 
       if (has_jvmti_events) {
@@ -191,6 +196,10 @@
     if (oopstorage_work) {
       cleanup_oopstorages();
     }
+
+    if (deflate_idle_monitors) {
+      ObjectSynchronizer::deflate_idle_monitors_using_JT();
+    }
   }
 }