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