message: Don't read the time if the worklist is empty.
  Summary: Don't read the time if the worklist is empty. PGO stats show that we usually don't enter the loop.
diff: @@ -501,6 +501,10 @@ template <class LockTraits>
  void ThreadLocalStatsT<LockTraits>::aggregate() {
  auto guard = link_->lock();
  + if (tlStats_.empty()) {
  + return;
  + }
  +
  // TODO: In the future it would be nice if the stats code used a
  // std::chrono::time_point instead of just a std::chrono::duration
  std::chrono::seconds now(get_legacy_stats_time());
  