Description of RPC configuration options

Configuration option = Default value	Description
[DEFAULT]
engine_life_check_timeout = 2	(IntOpt) RPC timeout for the engine liveness check that is used for stack locking.
matchmaker_heartbeat_freq = 300	(IntOpt) Heartbeat frequency.
matchmaker_heartbeat_ttl = 600	(IntOpt) Heartbeat time-to-live.
rpc_backend = rabbit	(StrOpt) The messaging driver to use, defaults to rabbit. Other drivers include qpid and zmq.
rpc_cast_timeout = 30	(IntOpt) Seconds to wait before a cast expires (TTL). Only supported by impl_zmq.
rpc_conn_pool_size = 30	(IntOpt) Size of RPC connection pool.
rpc_response_timeout = 60	(IntOpt) Seconds to wait for a response from a call.
rpc_thread_pool_size = 64	(IntOpt) Size of RPC greenthread pool.