id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
7552	win_iocp_io_service hangs due to a race condition	danielg@…	chris_kohlhoff	"The fix to #6321 introduced a bug that can cause the io_service to hang.

Example code (hangs eventually):
{{{
int main()
{
	for (;;)
	{
		boost::asio::io_service ios;
		ios.post([]{ std::cout << '.'; });

		boost::thread_group threads;
		for (size_t i = 0; i < 2; ++i)
			threads.create_thread([&]{ ios.run(); });
		threads.join_all();
	}
}
}}}

Suppose that one of the threads read the posted operation, completed it and got to the ''work_finished'' function where it decremented ''outstanding_work'' to 0 and entered the ''stop'' function. Now the second thread starts. In the ''run'' function it sees that ''outstanding_work'' is 0 so it sets ''stopped'' to 1 and returns. Back in the first thread ''PostQueuedCompletionStatus(iocp_.handle, 0, 0, 0)'' isn't called since ''stopped'' is already 1. ''do_one'' returns 1 and is called again. ''GetQueuedCompletionStatus'' returns WAIT_TIMEOUT because the operation queue is empty, which causes the loop to continue to the next iteration ad infinitum."	Bugs	closed	To Be Determined	asio	Boost 1.49.0	Regression	fixed	asio windows hang