As followup work to
CASSANDRA-8457, we need to move streaming to use netty.
Streaming 2.0 (
CASSANDRA-5286) brought many good improvements to how files are transferred between nodes in a cluster. However, the low-level details of the current streaming implementation does not line up nicely with a non-blocking model, so I think this is a good time to review some of those details and add in additional goodness. The current implementation assumes a sequential or "single threaded" approach to the sending of stream messages as well as the transfer of files. In short, after several iterative prototypes, I propose the following:
1) use a single bi-diredtional connection (instead of requiring to two sockets & two threads)
2) send the "non-file" StreamMessage s (basically anything not OutboundFileMessage) via the normal internode messaging. This will require a slight bit more management of the session (the ability to look up a StreamSession from a static function on StreamManager, but we have have most of the pieces we need for this already.
3) switch to a non-blocking IO model (facilitated via netty)
4) Allow files to be streamed in parallel (
CASSANDRA-4663) - this should just be a thing already
5) If the entire sstable is to streamed, in addition to the DATA component, transfer all the components of the sstable (primary index, bloom filter, stats, and so on). This way we can avoid the CPU and GC pressure from deserializing the stream into objects. File streaming then amounts to a block-level transfer.
Note: The progress/results of CASSANDRA-11303 will need to be reflected here, as well.