--- old/src/hotspot/share/runtime/thread.cpp	2020-07-12 22:24:43.535389488 +0200
+++ new/src/hotspot/share/runtime/thread.cpp	2020-07-12 22:24:43.107388672 +0200
@@ -2384,7 +2384,7 @@
     check_and_handle_async_exceptions();
   }
 
-  if (is_ea_obj_deopt_suspend()) {
+  if (is_obj_deopt_suspend()) {
     frame_anchor()->make_walkable(this);
     wait_for_object_deoptimization();
   }
@@ -2586,26 +2586,52 @@
   assert(this == Thread::current(), "invariant");
   JavaThreadState state = thread_state();
 
+  bool should_spin_wait = true;
   do {
     set_thread_state(_thread_blocked);
     set_suspend_equivalent();
-    MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
-    if (is_ea_obj_deopt_suspend()) {
-      ml.wait();
+    {
+      MonitorLocker ml(this, EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
+      if (EscapeBarrier::deoptimizing_objects_for_all_threads() ||
+          (is_obj_deopt_suspend() && !should_spin_wait)) {
+        ml.wait();
+      }
+      should_spin_wait = should_spin_wait && is_obj_deopt_suspend();
     }
-    if (handle_special_suspend_equivalent_condition()) {
-      MutexUnlocker mu(EscapeBarrier_lock, Monitor::_no_safepoint_check_flag);
-      java_suspend_self();
+    // Single deoptimization is typically very short. Microbenchmarks
+    // showed 5% better performance when spinning
+    if (should_spin_wait) {
+      // Inspired by HandshakeSpinYield
+      const jlong max_spin_time_ns = 100 /* us */ * (NANOUNITS / MICROUNITS);
+      const int free_cpus = os::active_processor_count() - 1;
+      jlong spin_time_ns = (5 /* us */ * (NANOUNITS / MICROUNITS)) * free_cpus; // zero on UP
+      spin_time_ns = spin_time_ns > max_spin_time_ns ? max_spin_time_ns : spin_time_ns;
+      jlong spin_start = os::javaTimeNanos();
+      while (is_obj_deopt_suspend()) {
+        os::naked_yield();
+        if ((os::javaTimeNanos() - spin_start) > spin_time_ns) {
+          should_spin_wait = false;
+          break;
+        }
+      }
     }
     set_thread_state_fence(state);
-  } while (is_ea_obj_deopt_suspend());
 
-  // Since we are not using a regular thread-state transition helper here,
-  // we must manually emit the instruction barrier after leaving a safe state.
-  OrderAccess::cross_modify_fence();
-  if (state != _thread_in_native) {
-    SafepointMechanism::block_if_requested(this);
-  }
+    if (handle_special_suspend_equivalent_condition()) {
+      java_suspend_self_with_safepoint_check();
+    }
+
+    // Since we are not using a regular thread-state transition helper here,
+    // we must manually emit the instruction barrier after leaving a safe state.
+    OrderAccess::cross_modify_fence();
+    if (state != _thread_in_native) {
+      SafepointMechanism::block_if_requested(this);
+    }
+
+    // Check for another deopt suspend _after_ checking for safepont/handshake,
+    // or otherwise a stale value can be seen if the flag was changed with a
+    // handshake while the current thread was _thread_blocked above.
+  } while (is_obj_deopt_suspend());
 }
 
 #ifdef ASSERT
@@ -2637,7 +2663,7 @@
     SafepointMechanism::block_if_requested(thread);
   }
 
-  if (thread->is_ea_obj_deopt_suspend()) {
+  if (thread->is_obj_deopt_suspend()) {
     thread->wait_for_object_deoptimization();
   }
 
@@ -4616,6 +4642,9 @@
     // to do callbacks into the safepoint code. However, the safepoint code is not aware
     // of this thread since it is removed from the queue.
     p->set_terminated_value();
+
+    // Notify threads waiting in EscapeBarriers
+    EscapeBarrier::thread_removed(p);
   } // unlock Threads_lock
 
   // Since Events::log uses a lock, we grab it outside the Threads_lock