--- a/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp	Sun Aug 25 13:27:54 2019 +0200
@@ -408,7 +408,9 @@
 }
 
 size_t JfrCheckpointManager::flush_type_set() {
-  return JfrTypeManager::flush_type_set();
+  const size_t elements = JfrTypeManager::flush_type_set();
+  flush();
+  return elements;
 }
 
 void JfrCheckpointManager::create_thread_checkpoint(Thread* t) {

--- a/src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp	Sun Aug 25 13:27:54 2019 +0200
@@ -295,9 +295,7 @@
 template <typename Functor>
 static u4 invoke_with_flush_event(Functor& f) {
   const u4 elements = invoke(f);
-  if (elements != 0) {
-    write_flush_event(f);
-  }
+  write_flush_event(f);
   return elements;
 }
 
@@ -610,8 +608,10 @@
     return total_elements;
   }
   total_elements += storage_elements;
-  total_elements += flush_stacktrace(_stack_trace_repository, _chunkwriter);
-  if (_string_pool.modified()) {
+  if (_stack_trace_repository.is_modified()) {
+    total_elements += flush_stacktrace(_stack_trace_repository, _chunkwriter);
+  }
+  if (_string_pool.is_modified()) {
     total_elements += flush_stringpool(_string_pool, _chunkwriter);
   }
   total_elements += flush_typeset(_checkpoint_manager, _chunkwriter);
@@ -622,14 +622,13 @@
   assert(_chunkwriter.is_valid(), "invariant");
   ResourceMark rm;
   HandleMark hm;
-  reset_thread_local_buffer();
+  write_metadata_in_flushpoint = (msgs & MSGBIT(MSG_FLUSHPOINT_METADATA));
   ++flushpoint_id;
-  write_metadata_in_flushpoint = (msgs & MSGBIT(MSG_FLUSHPOINT_METADATA));
+  reset_thread_local_buffer();
   FlushFunctor flushpoint(*this);
   Flush fl(_chunkwriter, flushpoint);
   invoke_with_flush_event(fl);
   write_thread_local_buffer(_chunkwriter);
-  _checkpoint_manager.flush();
   _repository.flush_chunk();
 }
 
@@ -643,8 +642,10 @@
 //
 void JfrRecorderService::pre_safepoint_write() {
   assert(_chunkwriter.is_valid(), "invariant");
-  flush_stacktrace_checkpoint(_stack_trace_repository, _chunkwriter, false);
-  if (_string_pool.modified()) {
+  if (_stack_trace_repository.is_modified()) {
+    flush_stacktrace_checkpoint(_stack_trace_repository, _chunkwriter, false);
+  }
+  if (_string_pool.is_modified()) {
     flush_stringpool_checkpoint(_string_pool, _chunkwriter);
   }
   if (LeakProfiler::is_running()) {
@@ -674,9 +675,8 @@
 //
 void JfrRecorderService::safepoint_write() {
   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
-
   flush_stacktrace_checkpoint(_stack_trace_repository, _chunkwriter, true);
-  if (_string_pool.modified()) {
+  if (_string_pool.is_modified()) {
     flush_stringpool_checkpoint_safepoint(_string_pool, _chunkwriter);
   }
   if (LeakProfiler::is_running()) {

--- a/src/hotspot/share/jfr/recorder/stacktrace/jfrStackTraceRepository.cpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/stacktrace/jfrStackTraceRepository.cpp	Sun Aug 25 13:27:54 2019 +0200
@@ -70,6 +70,12 @@
   _instance = NULL;
 }
 
+static traceid last_id = 0;
+
+bool JfrStackTraceRepository::is_modified() const {
+  return last_id != _next_id;
+}
+
 size_t JfrStackTraceRepository::write_impl(JfrChunkWriter& sw, bool clear) {
   MutexLocker lock(JfrStacktrace_lock, Mutex::_no_safepoint_check_flag);
   assert(_entries > 0, "invariant");
@@ -92,6 +98,7 @@
     memset(_table, 0, sizeof(_table));
     _entries = 0;
   }
+  last_id = _next_id;
   return count;
 }
 

--- a/src/hotspot/share/jfr/recorder/stacktrace/jfrStackTraceRepository.hpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/stacktrace/jfrStackTraceRepository.hpp	Sun Aug 25 13:27:54 2019 +0200
@@ -55,6 +55,8 @@
   bool initialize();
   static void destroy();
 
+  bool is_modified() const;
+
   size_t write_impl(JfrChunkWriter& cw, bool clear);
   static void write_metadata(JfrCheckpointWriter& cpw);
   traceid write(JfrCheckpointWriter& cpw, traceid id, unsigned int hash);

--- a/src/hotspot/share/jfr/recorder/stringpool/jfrStringPool.cpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/stringpool/jfrStringPool.cpp	Sun Aug 25 13:27:54 2019 +0200
@@ -57,7 +57,7 @@
 static void set_serialized_generation() {
   set_value(OrderAccess::load_acquire(&store_generation), &serialized_generation);
 }
-bool JfrStringPool::modified() {
+bool JfrStringPool::is_modified() {
   return serialized_generation != OrderAccess::load_acquire(&store_generation);
 }
 JfrStringPool& JfrStringPool::instance() {

--- a/src/hotspot/share/jfr/recorder/stringpool/jfrStringPool.hpp	Sun Aug 25 10:12:57 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/stringpool/jfrStringPool.hpp	Sun Aug 25 13:27:54 2019 +0200
@@ -71,7 +71,7 @@
   static JfrStringPool* create(JfrChunkWriter& cw);
   bool initialize();
   static void destroy();
-  static bool modified();
+  static bool is_modified();
 
   friend class JfrRecorder;
   friend class JfrRecorderService;