Intel C++ Compiler 16.0 OpenMP initialization of thread local static member in template class

Hi,

it appears that on Windows thread local storage (TLS) static members in template classes do not get initialized properly in worker threads.

Here is a (maybe not so minimal) reproducing test:

--------------------------------------------------------------------------------------------------------------------------------------------------

#include <iostream>
#include <sstream>
#include <string>
#include <thread>
#include <omp.h>

#define NTHREADS 2
#define THREAD thread_local

class MyClass
{
public:
  MyClass(int n): m_n(n)
  {
    std::ostringstream s;
    s << "MyClass::MyClass(int) in thread "<< std::this_thread::get_id() << ", m_n = "<< m_n << std::endl;
    std::cout << s.str();
  }
  MyClass(MyClass & other): m_n(other.m_n)
  {
    std::ostringstream s;
    s << "MyClass::MyClass(MyClass &) in thread "<< std::this_thread::get_id() << ", m_n = "<< m_n << std::endl;
    std::cout << s.str();
  }
  long long m_n;
};

/*=======================================*/

template<typename T>
class TemplateContainer
{
public:
  typedef T obj_type;
  static void print();
  static THREAD obj_type s_obj;
};

template<typename T>
THREAD typename TemplateContainer<T>::obj_type TemplateContainer<T>::s_obj(1);

template <typename T>
void TemplateContainer<T>::print()
{
  std::ostringstream s;
  s << "TemplateContainer<>::print() in thread "<< std::this_thread::get_id() << ", MyClass::m_n = "<< s_obj.m_n << std::endl;
  std::cout << s.str();
}

/*=======================================*/

class NonTemplateContainer
{
public:
  typedef MyClass obj_type;
  static void print();
  static THREAD obj_type s_obj;
};

THREAD typename NonTemplateContainer::obj_type NonTemplateContainer::s_obj(2);

void NonTemplateContainer::print()
{
  std::ostringstream s;
  s << "NonTemplateContainer::print() in thread "<< std::this_thread::get_id() << ", MyClass::m_n = "<< s_obj.m_n << std::endl;
  std::cout << s.str();
}

/*=======================================*/

int main()
{
  omp_set_dynamic(0);
  omp_set_num_threads(NTHREADS);
  std::cout << "======================================================================"<< std::endl;
#pragma omp parallel
  NonTemplateContainer::print();
  std::cout << "======================================================================"<< std::endl;
#pragma omp parallel
  TemplateContainer<MyClass>::print();
  std::cout << "======================================================================"<< std::endl;
}

--------------------------------------------------------------------------------------------------------------------------------------

When compiled in Intel Parallel Studio XE 2016 (i.e. MSVS 2015 + Intel Compiler 16.0 Update 3) in Debug configuration with all default options plus /Qopenmp and /Qstd=c++11, this code produces the following typical output:

MyClass::MyClass(int) in thread 13724, m_n = 2
MyClass::MyClass(int) in thread 13724, m_n = 1
======================================================================
MyClass::MyClass(int) in thread 14276, m_n = 2
NonTemplateContainer::print() in thread 13724, MyClass::m_n = 2
MyClass::MyClass(int) in thread 11568, m_n = 2
NonTemplateContainer::print() in thread 11568, MyClass::m_n = 2
======================================================================
TemplateContainer<>::print() in thread 13724, MyClass::m_n = 1
TemplateContainer<>::print() in thread 11568, MyClass::m_n = 2073053888752
======================================================================

Here we see that static TLS member s_obj was first initialized in master thread in both non-template and template class, and then in two spawned worker threads for the non-template container. For the template container there was no static initialization in worker threads. Since one of the TemplateContainer<>::print() functions of the parallel region seems to be executed in the master thread (why?), it outputs the initialized value, but the other one executed in worker thread outputs non-initialized garbage - that is, if you're lucky, mostly it will just crash with access violation.

The same code on Linux (CentOS 6.8) with icpc 16.0.3 compiled with -qopenmp -g -std=c++11 produces:

======================================================================
MyClass::MyClass(int) in thread 140110818879296, m_n = 2
MyClass::MyClass(int) in thread 140110660962176, m_n = 2
MyClass::MyClass(int) in thread 140110818879296, m_n = 1
MyClass::MyClass(int) in thread 140110660962176, m_n = 1
NonTemplateContainer::print() in thread 140110818879296, MyClass::m_n = 2
NonTemplateContainer::print() in thread 140110660962176, MyClass::m_n = 2
======================================================================
TemplateContainer<>::print() in thread 140110660962176, MyClass::m_n = 1
TemplateContainer<>::print() in thread 140110818879296, MyClass::m_n = 1
======================================================================

Here only two threads are used and in both of them TemplateContainer::s_obj seems to be initialized correctly.

Can anyone explain whether I'm doing something wrong or if this seems to be a bug?

P.S.: I'm running tests with OMP_NUM_THREADS set to 1 and then number of threads dynamically changed to 2 in code (see main() above), but looks like the way the number of threads is set is irrelevant.