id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
9385,Call current_exception in concurrent manner for the same exception object,cupper.jj@…,Emil Dotchevski,"In attached file you can find minimal test that crashes when uses boost implementation of exception_ptr. It happens when call current_exception in concurrent manner for the same exception object.

Why does I expect that it should work? Because documentation does not say opposite (and it works in std implementation).

In boost till 1.42([http://www.boost.org/doc/libs/1_43_0/libs/exception/doc/exception_ptr.html]) was said:
  Therefore, in general it is not safe to call rethrow_exception concurrently to throw the same exception object into multiple threads.

And I have called it under mutex. But even in 1.42 was not said that call current_exception in concurrent manner (for the same exception object) not allowed.

The problem in class boost::exception_detail::exception

{{{#!c++
class boost::exception_detail::exception
{
...
  mutable exception_detail::refcount_ptr<exception_detail::error_info_container> data_;
}}}

when you call current_exception it's cloning current object of exception that create race condition.

The documentation not enough clear about thread safety restrictions for current_exception and rethrow_excepoption.

Here is back trace
{{{
#0  0x000000000225a110 in ?? ()
#1  0x0000000000410455 in boost::exception_detail::refcount_ptr<boost::exception_detail::error_info_container>::add_ref() ()
#2  0x000000000040dc0a in boost::exception_detail::refcount_ptr<boost::exception_detail::error_info_container>::refcount_ptr(boost::exception_detail::refcount_ptr<boost::exception_detail::error_info_container> const&) ()
#3  0x000000000040c1ba in boost::exception::exception(boost::exception const&) ()
#4  0x0000000000413033 in boost::exception_detail::current_exception_std_exception_wrapper<std::runtime_error>::current_exception_std_exception_wrapper(boost::exception_detail::current_exception_std_exception_wrapper<std::runtime_error> const&) ()
#5  0x00000000004130bd in boost::exception_detail::clone_impl<boost::exception_detail::current_exception_std_exception_wrapper<std::runtime_error> >::clone_impl(boost::exception_detail::clone_impl<boost::exception_detail::current_exception_std_exception_wrapper<std::runtime_error> > const&) ()
#6  0x0000000000420563 in boost::exception_detail::clone_impl<boost::exception_detail::current_exception_std_exception_wrapper<std::runtime_error> >::rethrow() const ()
#7  0x000000000040cca8 in boost::rethrow_exception(boost::exception_ptr const&) ()
#8  0x0000000000409825 in executer(boost::mutex&, boost::exception_ptr) ()
#9  0x0000000000421ff2 in void boost::_bi::list2<boost::reference_wrapper<boost::mutex>, boost::_bi::value<boost::exception_ptr> >::operator()<void (*)(boost::mutex&, boost::exception_ptr), boost::_bi::list0>(boost::_bi::type<void>, void (*&)(boost::mutex&, boost::exception_ptr), boost::_bi::list0&, int) ()
#10 0x00000000004211cd in boost::_bi::bind_t<void, void (*)(boost::mutex&, boost::exception_ptr), boost::_bi::list2<boost::reference_wrapper<boost::mutex>, boost::_bi::value<boost::exception_ptr> > >::operator()() ()
#11 0x0000000000420122 in boost::detail::thread_data<boost::_bi::bind_t<void, void (*)(boost::mutex&, boost::exception_ptr), boost::_bi::list2<boost::reference_wrapper<boost::mutex>, boost::_bi::value<boost::exception_ptr> > > >::run() ()
#12 0x00007fdff7194d29 in thread_proxy () from /home/roman-s/libraries/boost_1_53_0/stage/lib/libboost_thread.so.1.53.0
#13 0x00007fdff6f71f8e in start_thread (arg=0x7fdff5178700) at pthread_create.c:311
#14 0x00007fdff6782a0d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
}}}

In my project where we use boost::exception on more difficult case, problem happens all time in refcount_ptr that try delete already deleted object. In this synthetical test problems arrives in a little bit another manner. But it's exactly reproduce our logic. Of course we can avoid this problem, but problem is.

Thank you.",Bugs,new,To Be Determined,exception,Boost 1.53.0,Problem,,boost::exception_detail::refcount_ptr,