#include<iostream>
#include<pthread.h>
using namespace std;

class Single
{
public:
 static pthread_mutex_t mtx;
 static Single* get_Single()
 {
  if(p==NULL)
  {
   pthread_mutex_lock(&mtx);
   if(p==NULL)
   {
    p=new Single;
   }
   pthread_mutex_unlock(&mtx);
  }
  return p;
 }
private:
 static Single* volatile p;
 Single()
 {
 }
};
pthread_mutex_t Single ::mtx=PTHREAD_MUTEX_INITIALIZER;
Single* Single::p=NULL;
void* func1(void* arg)
{
 while(1)
 {
  Single* tmp1=Single::get_Single();
  cout<<"tmp1  "<<tmp1<<endl;
  sleep(1000);
 }
}

void* func2(void* arg)
{
 while(1)
 {
  Single* tmp2=Single::get_Single();
  cout<<"tmp2  "<<tmp2<<endl;
  sleep(1000);
 }
}

int main()
{
 pthread_t pt1;
 pthread_t pt2;
 int ret1=pthread_create(&pt1,0,func1,0);
 if(ret1!=0)
 {
  cout<<"ERROR!!!"<<endl;
 }
 int ret2=pthread_create(&pt2,0,func2,0);
 if(ret2!=0)
 {
  cout<<"ERROR!!!"<<endl;
 }
 pthread_join(pt1,0);
 pthread_join(pt2,0);
 return 0;
}