Github user lvfangmin commented on the issue:
https://github.com/apache/zookeeper/pull/593
@maoling, sorry for the lately reply, I forgot to reply this PR.
We've done some benchmark when we added this code a year ago, I was trying
to find some benchmark data at that point, but I cannot find it yet.
I've done some benchmark internally today, and found the performance of
different buffer size is highly depending on the traffic pattern, and may
actually introduce higher latency, so it's hard to give a suggested buffer
size. But I don't think the extra negotiation time during connecting is a
problem here, since we only set the buffer size between quorum servers, which
is very few connections and it's stable.
Internally, we're not customizing the buffer size with this option anymore,
instead we're using the system TCP Autotuning options net.ipv4.tcp_wmem and
net.ipv4.tcp_rmem, which are more flexible and will automatically adjusts
socket buffer sizes as needed to optimally balance TCP performance and memory
usage, so we're not customizing the buffer size anymore.
**As for the unit test**, those SO_SENDBUF and SO_RCVBUF options are used
by the platform's networking code as a hint for the size to set the underlying
network I/O buffers, so it doesn't always guarantee it will use what you told
it to. So I think this test is not that useful from this point of view.
Overall, I think we probably don't need this custom option anymore because
it's hard to configure right.
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