dlclose not releasing the library handle in case static class members are accessed like calling boost::this_fiber::get_id()

Question

I have a scenario as bellow and not able to close the library

liba.so

  #include <iostream>
  #include <boost/fiber/all.hpp>
  using namespace std;

  int func1(int)
  {
    cout << "this fiber id " << boost::this_fiber::get_id() << endl; // if this line is commented out then the problem resolved.
    cout << "It is a func1" << endl;
    return 1;
  }

---

I created a library out of the cpp file where -fno-unique-symbol is specified so that it should not hold back the symbol.

main code

#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <sys/types.h>
using namespace std;
int fun(string & flName)  {
  void *handle;
  typedef int (*fn)(int);
  fn fn1;
  handle = dlopen(flName.c_str(), RTLD_LOCAL|RTLD_LAZY);
  fn1 = (fn)dlsym(handle, "_Z5func1I");
  (*fn1)(2);
  cout << "handle :" << handle << endl;
  int ext_code = dlclose(handle);
  printf ("end exit code %d\n", ext_code);
}

int main(void)    {
  std::string fileName("dirpath/liba.so");
   fun(fileName);
   fun(fileName);
   fun(fileName);
   return 0;
}

output, when this_fiber is commented out

• handle : 0x234567
• end exit code 0
• handle :0x345678
• end exit code 0
• handle : 0x456789
• end exit code 0

----- but when this_fiber::get_id() is active then

• handle : 0x234567
• end exit code 0
• handle :0x234567
• end exit code 0
• handle : 0x234567
• end exit code 0

Can someone explain the reason for holding back the library handle and tell me how to tweak the code so that I can close the library