C++ thread_local_storage_01

Table of contents

std::atomic<int>              atomic_integer_var                    = 0;
thread_local std::atomic<int> atomic_integer_var_with_local_storage = 0;

void foo_1()
{
  ++atomic_integer_var;
  fmt::print( "foo_1: {}\n", atomic_integer_var.load() );
}

void foo_2()
{
  ++atomic_integer_var_with_local_storage;
  fmt::print( "foo_2: {}\n", atomic_integer_var_with_local_storage.load() );
}

int main( [[maybe_unused]] int argc, [[maybe_unused]] char **argv )
{
  fmt::print( "All threads shares the same variable\n" );
  std::thread t1( foo_1 );
  std::thread t2( foo_1 );
  std::thread t3( foo_1 );
  t1.join();
  t2.join();
  t3.join();

  std::thread ta( foo_2 );
  std::thread tb( foo_2 );
  std::thread tc( foo_2 );
  ta.join();
  tb.join();
  tc.join();
  return 0;
}

Possible output

All threads shares the same variable
foo_1: 1
foo_1: 3
foo_1: 2
foo_2: 1
foo_2: 1
foo_2: 1

References

• Udemy Modern C++ Concurrency in Depth title