id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
3958	ssl::stream async_read_some and async_write_some handlers never run concurrently	L McGuinness <lorcan.mcguinness@…>	chris_kohlhoff	"Handlers passed to ssl::stream::async_read_some and ssl::stream::async_write_some are always invoked in the context of a strand.  This strand is a member of openssl_stream_service, which is typically a process-wide instance.

The effect of this is that a time-consuming async_read_some handler on one ssl::stream instance can block all other async_read_some and async_write_some handlers on other instances of ssl::stream.

The code that does this is in boost/asio/ssl/detail/openssl_operation.hpp.  Line 319 performs strand::wrap on the callback to openssl_operation::async_write_handler.  At lines 367 and 373, async_write_handler invokes the user's handler function (passed to ssl::stream::async_write_some).  This runs in the context of strand_.

The strand instance in this case is always openssl_stream_service::strand_, as can be seen in asio/ssl/detail/openssl_stream_service.hpp, line 395.

The situation for async_read_handler is similar."	Bugs	closed	To Be Determined	asio	Boost 1.42.0	Problem	fixed	openssl ssl strand concurrency asio	samjmill@…