thread local - what is the advantage of making std::vector thread_local? -

seeing crash in erase()/pop_back() in multithreaded enviroment, looks iterator doesn't invalidated. advantage of thread_local in defining vector, iterators have invalidation problem in case.

#include <iostream> #include <vector> #include <iterator> #include <assert.h>   #include <thread>  thread_local std::vector<int> v;  void threadfuncerase(std::vector<int>::iterator i){     std::cout << "threadfuncerase"<< std::endl;     v.erase(i); }  void threadfuncpop(){     std::cout << "threadfuncpop"<< std::endl;     v.pop_back(); }  int main() {     v.push_back(1);     v.push_back(2);      std::vector<int>::iterator i1 = v.begin(), i2 = v.end() - 1, i3 = v.begin() + 1;     std::cout << "main"<< std::endl;      std::thread t1(threadfuncpop);     std::thread t2(threadfuncerase, /*i2*/v.end() - 1);     //std::thread t2(threadfuncpop);      t1.join();     t2.join(); }