--- old/src/share/vm/jfr/support/jfrThreadLocal.hpp	2021-01-22 14:12:45.182244981 +0800
+++ new/src/share/vm/jfr/support/jfrThreadLocal.hpp	2021-01-22 14:12:45.071240646 +0800
@@ -51,6 +51,7 @@
   mutable u4 _stackdepth;
   volatile jint _entering_suspend_flag;
   bool _dead;
+  traceid _parent_trace_id;
 
   JfrBuffer* install_native_buffer() const;
   JfrBuffer* install_java_buffer() const;
@@ -127,6 +128,10 @@
     _trace_id = thread_id;
   }
 
+  traceid parent_thread_id() const {
+    return _parent_trace_id;
+  }
+
   void set_cached_stack_trace_id(traceid id, unsigned int hash = 0) {
     _stack_trace_id = id;
     _stack_trace_hash = hash;