--- a/src/hotspot/share/jfr/recorder/checkpoint/types/jfrType.cpp	Fri May 17 15:53:21 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/checkpoint/types/jfrType.cpp	Fri May 17 16:02:27 2019 +0200
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,7 +39,7 @@
 #include "jfr/recorder/checkpoint/types/jfrThreadState.hpp"
 #include "jfr/recorder/checkpoint/types/jfrTypeSet.hpp"
 #include "jfr/support/jfrThreadLocal.hpp"
-#include "jfr/writers/jfrJavaEventWriter.hpp"
+#include "jfr/utilities/jfrThreadIterator.hpp"
 #include "memory/metaspaceGCThresholdUpdater.hpp"
 #include "memory/referenceType.hpp"
 #include "memory/universe.hpp"
@@ -93,12 +93,10 @@
 // Requires a ResourceMark for get_thread_name/as_utf8
 void JfrCheckpointThreadClosure::do_thread(Thread* t) {
   assert(t != NULL, "invariant");
-  assert_locked_or_safepoint(Threads_lock);
   const JfrThreadLocal* const tl = t->jfr_thread_local();
   assert(tl != NULL, "invariant");
-  if (tl->is_dead()) {
-    return;
-  }
+  assert(!tl->is_dead(), "invariant");
+  assert(!tl->is_excluded(), "invariant");
   ++_count;
   _writer.write_key(tl->thread_id());
   _writer.write(t->name());
@@ -110,7 +108,6 @@
     _writer.write(java_lang_Thread::thread_id(jt->threadObj()));
     _writer.write(JfrThreadGroup::thread_group_id(jt, _curthread));
     // since we are iterating threads during a safepoint, also issue notification
-    JfrJavaEventWriter::notify(jt);
     return;
   }
   _writer.write((const char*)NULL); // java name
@@ -119,13 +116,18 @@
 }
 
 void JfrThreadConstantSet::serialize(JfrCheckpointWriter& writer) {
-  assert(SafepointSynchronize::is_at_safepoint(), "invariant");
   JfrCheckpointThreadClosure tc(writer);
-  Threads::threads_do(&tc);
+  JfrJavaThreadIterator javathreads;
+  while (javathreads.has_next()) {
+    tc.do_thread(javathreads.next());
+  }
+  JfrNonJavaThreadIterator nonjavathreads;
+  while (nonjavathreads.has_next()) {
+    tc.do_thread(nonjavathreads.next());
+  }
 }
 
 void JfrThreadGroupConstant::serialize(JfrCheckpointWriter& writer) {
-  assert(SafepointSynchronize::is_at_safepoint(), "invariant");
   JfrThreadGroup::serialize(writer);
 }
 
@@ -298,16 +300,23 @@
 
 class TypeSetSerialization {
  private:
+  size_t _elements;
   bool _class_unload;
+  bool _flushpoint;
  public:
-  explicit TypeSetSerialization(bool class_unload) : _class_unload(class_unload) {}
+  explicit TypeSetSerialization(bool class_unload, bool flushpoint) : _elements(0), _class_unload(class_unload), _flushpoint(flushpoint) {}
   void write(JfrCheckpointWriter& writer, JfrCheckpointWriter* leakp_writer) {
-    JfrTypeSet::serialize(&writer, leakp_writer, _class_unload);
+    MutexLocker cld_lock(SafepointSynchronize::is_at_safepoint() ? NULL : ClassLoaderDataGraph_lock);
+    MutexLocker lock(SafepointSynchronize::is_at_safepoint() ? NULL : Module_lock);
+    _elements = JfrTypeSet::serialize(&writer, leakp_writer, _class_unload, _flushpoint);
+  }
+  size_t elements() const {
+    return _elements;
   }
 };
 
 void ClassUnloadTypeSet::serialize(JfrCheckpointWriter& writer) {
-  TypeSetSerialization type_set(true);
+  TypeSetSerialization type_set(true, false);
   if (LeakProfiler::is_running()) {
     JfrCheckpointWriter leakp_writer(false, true, Thread::current());
     type_set.write(writer, &leakp_writer);
@@ -317,8 +326,19 @@
   type_set.write(writer, NULL);
 };
 
+void FlushTypeSet::serialize(JfrCheckpointWriter& writer) {
+  assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
+  TypeSetSerialization type_set(false, true);
+  type_set.write(writer, NULL);
+  _elements = type_set.elements();
+}
+
+size_t FlushTypeSet::elements() const {
+  return _elements;
+}
+
 void TypeSet::serialize(JfrCheckpointWriter& writer) {
-  TypeSetSerialization type_set(false);
+  TypeSetSerialization type_set(false, false);
   if (LeakProfiler::is_suspended()) {
     JfrCheckpointWriter leakp_writer(false, true, Thread::current());
     type_set.write(writer, &leakp_writer);
@@ -335,20 +355,23 @@
 void JfrThreadConstant::serialize(JfrCheckpointWriter& writer) {
   assert(_thread != NULL, "invariant");
   assert(_thread == Thread::current(), "invariant");
-  assert(_thread->is_Java_thread(), "invariant");
-  assert(!_thread->jfr_thread_local()->has_thread_checkpoint(), "invariant");
   ResourceMark rm(_thread);
-  const oop threadObj = _thread->threadObj();
-  assert(threadObj != NULL, "invariant");
-  const u8 java_lang_thread_id = java_lang_Thread::thread_id(threadObj);
+  HandleMark hm(_thread);
   const char* const thread_name = _thread->name();
-  const traceid thread_group_id = JfrThreadGroup::thread_group_id(_thread);
   writer.write_count(1);
   writer.write_key(_thread->jfr_thread_local()->thread_id());
   writer.write(thread_name);
   writer.write((traceid)_thread->osthread()->thread_id());
-  writer.write(thread_name);
-  writer.write(java_lang_thread_id);
-  writer.write(thread_group_id);
-  JfrThreadGroup::serialize(&writer, thread_group_id);
+  if (_thread->is_Java_thread()) {
+    JavaThread* const jt = (JavaThread*)_thread;
+    writer.write(jt->name());
+    writer.write(java_lang_Thread::thread_id(jt->threadObj()));
+    const traceid thread_group_id = JfrThreadGroup::thread_group_id(jt, jt);
+    writer.write(thread_group_id);
+    JfrThreadGroup::serialize(&writer, thread_group_id);
+    return;
+  }
+  writer.write((const char*)NULL); // java name
+  writer.write((traceid)0); // java thread id
+  writer.write((traceid)0); // java thread group
 }