I debugged through VS2010, it seems that the main thread gets stuck in thread_group::join_all(), while some remaining thread gets stuck in remove_this_thread(). The state of the threads are wait:UserRequest. Does it suggest that a thread cannot be deleted(by operator delete) or removed from the thread_group(by remove_thread()) before the join_all() ? Thanks. -----Original Message----- From: Tan, Tom (Shanghai) Sent: 2009-08-19 10:35 To: 'boost@lists.boost.org' Subject: [boost.thread] how to delete this thread from within the thread and thread hangs I am using boost::thread_group to create(using thread_group::create_thread()) and dispatch threads. In order to limit the max thread numbers, at the end of each thread, I remove the thread from the thread_group and delete the thread itself(so that I could decide whether new threads need to be created). However it hangs somewhere between the creation and deletion of the last thread (say the 999th one of 999 in total). My questions are: -1) is it OK to delete the thread from within itself like what I do? if not, what the best way to achieve this -2) why does my code hangs? Below are the related code: //1- code to create and dispatch thread { //mutex for map<thread_id, thread*> operations boost::mutex::scoped_lock lk(m_mutex_for_ptr); // create a thread for this->f(duplicate_hashes) boost::thread* p = m_thread_group.create_thread(boost::bind( &detectiveT<equal_predicate>::f, this, duplicate_hashes )); // save the thread_id -> thread pointer map for later lookup and deletion m_thread_ptrs.insert(make_pair(p->get_id(), p)); // log to console for debug cout << "thread created: " << p->get_id() << ", " << m_thread_group.size() << ", " m_thread_ptrs.size() << "\n"; } //2- code of the thread execution void f(list<map_iterator_type>& l) { Do_something(l); boost::this_thread::at_thread_exit(boost::bind( &detectiveT<equal_predicate>::remove_this_thread, this )); } //3- code to delete the thread itself void remove_this_thread() { { //mutex for map<thread_id, thread*> operations boost::mutex::scoped_lock lk(m_mutex_for_ptr); boost::thread::id this_id(boost::this_thread::get_id()); map<boost::thread::id, boost::thread*>::iterator itr; itr = (m_thread_ptrs.find(this_id)); if(m_thread_ptrs.end() != itr) { // remove it from the control of thread_group m_thread_group.remove_thread(itr->second); // delete it delete itr->second; // remove from the map m_thread_ptrs.erase(this_id); // log to console for debug cout << "thread erased: " << this_id << ", " << m_thread_group.size() << ", " << m_thread_ptrs.size() << "\n"; } } } Thanks.