--- old/src/share/vm/jfr/support/jfrThreadLocal.cpp	2021-01-22 14:12:44.519219088 +0800
+++ new/src/share/vm/jfr/support/jfrThreadLocal.cpp	2021-01-22 14:12:44.402214519 +0800
@@ -55,7 +55,11 @@
   _stack_trace_hash(0),
   _stackdepth(0),
   _entering_suspend_flag(0),
-  _dead(false) {}
+  _dead(false) {
+
+  Thread* thread = Thread::current_or_null();
+  _parent_trace_id = thread != NULL ? thread->jfr_thread_local()->trace_id() : (traceid)0;
+}
 
 u8 JfrThreadLocal::add_data_lost(u8 value) {
   _data_lost += value;
@@ -78,6 +82,7 @@
 static void send_java_thread_start_event(JavaThread* jt) {
   EventThreadStart event;
   event.set_thread(jt->jfr_thread_local()->thread_id());
+  event.set_parentThread(jt->jfr_thread_local()->parent_thread_id());
   event.commit();
 }
 
@@ -89,6 +94,9 @@
       send_java_thread_start_event((JavaThread*)t);
     }
   }
+  if (t->jfr_thread_local()->has_cached_stack_trace()) {
+    t->jfr_thread_local()->clear_cached_stack_trace();
+  }
 }
 
 static void send_java_thread_end_events(traceid id, JavaThread* jt) {