我boost::thread_group
用来创建(使用
thread_group::create_thread()
)和调度线程。为了限制最大线程数,在每个线程结束时,我从线程中thread_group
删除线程并删除线程本身(以便我可以决定是否需要创建新线程)。然而,它在最后一个线程的创建和删除之间挂起(比如总共 999 个线程中的第 999 个)。
我的问题是:
- 可以像我一样从内部删除线程吗?如果没有,实现这一目标的最佳方法是什么
- 为什么我的代码挂起?
下面是相关代码:
//1- 创建和调度线程的代码
{
//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 & 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-线程执行代码
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- 删除线程本身的代码
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";
}
}
}