The patch decreases the allocs when sending one AppEntry in msgappv2
stream from 30 to 9. This helps reduce CPU load when etcd is under
high write load.
msgappv2 stream is used to send all MsgApp, and replaces the
functionality of msgapp stream. Compared to v1, it has several
advantanges:
1. The output message is exactly the same with the input one, which
cannot be done in v1.
2. It uses one connection to stream persistently, which prevents message
reorder and saves the time to request stream.
3. It transmits 10 addiontional bytes in the procedure of committing one
proposal, which is trivia for idle time.
4. It transmits less bytes when committing mutliple proposals or keep
committing proposals.
Yicheng Qin