message: [c++ grpc] Handle hardware_concurrency returning 0
diff: @@ -47,6 +47,13 @@ public:
  if (0 == numThreads)
  {
  numThreads = std::thread::hardware_concurrency();
  + if (numThreads == 0)
  + {
  + // hardware_concurrency can return 0 if it can't figure out
  + // the hardware concurrency. Use a small number larger than 1.
  + const uint32_t recourseNumThreads = 2;
  + numThreads = recourseNumThreads;
  + }
  }
  //
  