Fix a profiler race condition

In multi-thread condition, EnableProfiler can
be called after RecordEvent is constructed. In this
case, RecordEvent constructor will not init anything,
but RecordEvent destructor will do something since EnableProfiler
was called.
This PR fixes it.

paddle/fluid/platform/profiler.cc

@@ -173,8 +173,9 @@ void PopEvent(const std::string& name, const DeviceContext* dev_ctx) {
 }
 
 RecordEvent::RecordEvent(const std::string& name, const DeviceContext* dev_ctx)
-    : start_ns_(PosixInNsec()) {
+    : is_enabled_(false), start_ns_(PosixInNsec()) {
   if (g_state == ProfilerState::kDisabled) return;
+  is_enabled_ = true;
   dev_ctx_ = dev_ctx;
   name_ = name;
   PushEvent(name_, dev_ctx_);
@@ -183,7 +184,7 @@ RecordEvent::RecordEvent(const std::string& name, const DeviceContext* dev_ctx)
 }
 
 RecordEvent::~RecordEvent() {
-  if (g_state == ProfilerState::kDisabled) return;
+  if (g_state == ProfilerState::kDisabled || !is_enabled_) return;
   DeviceTracer* tracer = GetDeviceTracer();
   if (tracer) {
     tracer->AddCPURecords(CurAnnotation(), start_ns_, PosixInNsec(),
@@ -193,14 +194,16 @@ RecordEvent::~RecordEvent() {
   PopEvent(name_, dev_ctx_);
 }
 
-RecordBlock::RecordBlock(int block_id) : start_ns_(PosixInNsec()) {
+RecordBlock::RecordBlock(int block_id)
+    : is_enabled_(false), start_ns_(PosixInNsec()) {
   if (g_state == ProfilerState::kDisabled) return;
+  is_enabled_ = true;
   SetCurBlock(block_id);
   name_ = string::Sprintf("block_%d", block_id);
 }
 
 RecordBlock::~RecordBlock() {
-  if (g_state == ProfilerState::kDisabled) return;
+  if (g_state == ProfilerState::kDisabled || !is_enabled_) return;
   DeviceTracer* tracer = GetDeviceTracer();
   if (tracer) {
     // We try to put all blocks at the same nested depth in the

paddle/fluid/platform/profiler.h

@@ -74,6 +74,7 @@ struct RecordEvent {
 
   ~RecordEvent();
 
+  bool is_enabled_;
   uint64_t start_ns_;
   // The device context is used by Event to get the current cuda stream.
   const DeviceContext* dev_ctx_;
@@ -89,6 +90,7 @@ struct RecordBlock {
   ~RecordBlock();
 
  private:
+  bool is_enabled_;
   std::string name_;
   uint64_t start_ns_;
 };