C ++ Boost导致崩溃

Question

I wrote some multithreaded application with c++11 features and boost, but I got annoying problem.

code:

boost::asio::io_service io_service;
Client c(io_service, server->hostname.c_str(), server->port.c_str());
io_service.run(); //here is problem , it causes crashes

bt:

#0 0x414910 std::vector<boost::asio::ip::basic_resolver_entry<boost::asio::ip::tcp>, std::allocator<boost::asio::ip::basic_resolver_entry<boost::asio::ip::tcp> > >::operator[](this=0x0, __n=0) (/usr/include/c++/4.8/bits/stl_vector.h:771)
#1 0x4131d4 boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp>::dereference(this=0x7fffdb7fd250) (/usr/include/boost/asio/ip/basic_resolver_iterator.hpp:183)
#2 0x411f24 boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp>::operator*(this=0x7fffdb7fd250) (/usr/include/boost/asio/ip/basic_resolver_iterator.hpp:123)
#3 0x40f8c6 Client::handle_resolve(this=0x7fffdb7fd800, err=..., endpoint_iterator=...) (*******Client.h:48)
#4 0x41c21f boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >::operator() (this=0x7fffdb7fd450, p=0x7fffdb7fd800, a1=..., a2=...) (/usr/include/boost/bind/mem_fn_template.hpp:280)
#5 0x41bd3b boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/bind/bind.hpp:392)
#6 0x41b74e boost::_bi::bind_t<void, boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >, boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/bind/bind_template.hpp:102)
#7 0x41adaf boost::asio::detail::binder2<boost::_bi::bind_t<void, boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >, boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/asio/detail/bind_handler.hpp:127)
#8 0x419fe1 boost::asio::asio_handler_invoke<boost::asio::detail::binder2<boost::_bi::bind_t<void, boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >, boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/asio/handler_invoke_hook.hpp:64)
#9 0x4191d8 boost_asio_handler_invoke_helpers::invoke<boost::asio::detail::binder2<boost::_bi::bind_t<void, boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >, boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/asio/detail/handler_invoke_helpers.hpp:37)
#10 0x41776c    boost::asio::detail::resolve_op<boost::asio::ip::tcp, boost::_bi::bind_t<void, boost::_mfi::mf2<void, Client, boost::system::error_code const&, boost::asio::ip::basic_resolver_iterator<boost::asio::ip::tcp> >, boost::_bi::list3<boost::_bi::value<Client*>, boost::arg<1> (*)() (/usr/include/boost/asio/detail/resolve_op.hpp:112)
#11 0x409df4    boost::asio::detail::task_io_service_operation::complete(this=0x7fffc8000db0, owner=..., ec=..., bytes_transferred=0) (/usr/include/boost/asio/detail/task_io_service_operation.hpp:37)
#12 0x40c4f7    boost::asio::detail::task_io_service::do_run_one(this=0x7fffc8000910, lock=..., this_thread=..., ec=...) (/usr/include/boost/asio/detail/impl/task_io_service.ipp:384)
#13 0x40bf27    boost::asio::detail::task_io_service::run(this=0x7fffc8000910, ec=...) (/usr/include/boost/asio/detail/impl/task_io_service.ipp:153)
#14 0x40c8a7    boost::asio::io_service::run(this=0x7fffdb7fdbc0) (/usr/include/boost/asio/impl/io_service.ipp:59)
#15 0x41d9a3    some_function(server=0x67e0b0) (*********Server.cpp:17)

Client.h

 void handle_resolve(const boost::system::error_code& err,
                            tcp::resolver::iterator endpoint_iterator)
        {
            tcp::endpoint endpoint = *endpoint_iterator; //48 line
            ip_ = endpoint.address().to_string();
            if (!err)
            {
                boost::asio::async_connect(socket_, endpoint_iterator,
                                           boost::bind(&Client::handle_connect, this,
                                                       boost::asio::placeholders::error));
            }

Just edited and added client part.

Answer 1

Looking at the stack trace, the problem is in Client::handle_resolve , line 48 of Client.h .

My best guess is that you're dereferencing an iterator without checking whether it's valid first. Perhaps you could post that function, if the error isn't obvious when you look at it.

UPDATE : My guess was correct: you're dereferencing the iterator before checking whether the operation succeeded. If it didn't, then the iterator won't be dereferencable.

Move the first two lines inside the if (!err) block.

Answer 2

Since I don't know io_service in detail, I have to guess a little bit. Which platform are you using? On boost 1.41 we had the problem that in QNX the automatic multithread capability was not detected correctly and therefore BOOST_ASIO_HAS_THREADS may not be set. This leads to a null_mutex being used instead of POSIX or Windows mutexes. Since std::vector itself is not thread safe, this could lead to the race condition with the segfault.